Disclosure and Market Readiness

Why Existing Homes Are the Next Big Building Performance Challenge

Australia’s next major building performance challenge is not only about new homes. It is about the homes that already exist.

Millions of Australians live in established homes that were designed, built or renovated before today’s energy efficiency expectations. These homes may be difficult to heat, difficult to cool, expensive to run or poorly prepared for future disclosure and retrofit programs.

That is why existing home energy ratings are becoming important. They create a practical way to understand how a home performs now, what may be holding it back and which upgrades may be worth considering first.

Why existing homes matter now

For many years, residential energy performance has been easier to regulate in new homes than in existing homes. New projects have design documents, approval pathways, modelling processes and construction requirements. Existing homes are more complex.

An established home may have been built decades ago, extended several times, upgraded without records or changed by different owners with different priorities. It may perform very differently from what its age, appearance or real estate photos suggest.

As Australia expands existing home rating pathways, the performance of these homes becomes easier to understand and easier to discuss in practical terms.

Why new-home standards are not enough

Improving new homes is essential, but it does not solve the existing homes challenge by itself. Most homes that people will live in over the coming decades have already been built.

A new seven-star home may perform well, but it does not improve the comfort of an older, draughty, poorly insulated home already occupied by a household today. It also does not reduce the energy demand of millions of existing dwellings that continue to use heating, cooling, hot water and appliances every day.

That is why the national conversation is shifting toward existing-home ratings, retrofit planning and market disclosure.

The scale of the challenge

Residential buildings account for a significant share of Australia’s electricity use and emissions. The update to the Trajectory for Low Energy Buildings notes that residential buildings are responsible for around 24% of Australia’s electricity use and more than 10% of total carbon emissions.

That means housing performance is not a minor technical issue. It is connected to household bills, electricity demand, emissions reduction, comfort, health, property value and national retrofit policy.

Existing homes sit at the centre of that challenge because they represent the housing stock people already occupy.

The comfort problem

Many existing homes are uncomfortable because the building fabric does not manage heat well. They may overheat in summer, lose warmth in winter or feel uneven from room to room.

Common causes include:

• poor or missing insulation
• unshaded glazing
• single glazing or weak window performance
• draughts and air leakage
• hot roof spaces
• poor ventilation
• inefficient heating and cooling systems
• renovation gaps between old and new areas

For summer comfort context, see Why Older Australian Homes Overheat in Summer.

The energy bill problem

Poor building performance often shows up as higher energy use. If a home gains heat too quickly, loses heat too easily or leaks conditioned air, heating and cooling systems need to work harder.

Homeowners may respond by installing larger systems, using portable heaters, running air conditioning for longer or adding solar without reducing the demand that sits underneath the bill.

A better approach is to understand whether the bill problem is caused by systems, building fabric, behaviour, climate, appliances or a combination of these factors.

The emissions problem

Existing homes are also part of Australia’s emissions challenge. Heating, cooling, hot water, cooking, lighting and appliances all contribute to household energy use, and inefficient homes can increase demand unnecessarily.

As the electricity grid changes and households electrify, building fabric still matters. A poorly performing home can require more energy to stay comfortable even if the appliances are efficient.

This is why emissions reduction is not only about switching systems. It is also about reducing avoidable demand through better building performance.

The documentation problem

Existing homes often have incomplete records. Original plans may be missing. Renovation documentation may be partial. Insulation may be hidden. Window performance may be unknown. Previous upgrades may not have been recorded.

This makes existing home assessment more complex than new-home modelling. The assessor may need to work with available plans, photos, site data, visible evidence, system information and pathway-specific assumptions.

For this reason, existing home rating is also a data challenge, not only a building challenge.

The renovation problem

Renovation is one of the best opportunities to improve home performance, but energy performance is often considered too late or too narrowly.

A renovation may replace a kitchen, open a living area or add a new room without addressing insulation, glazing, shading, ventilation or systems. The home may look improved but still overheat, leak air or use more energy than necessary.

For renovation pathway context, see Existing Home Energy Rating vs Renovation Energy Assessment.

The market information problem

Property markets usually make visible features easy to compare. Buyers can see the kitchen, bathrooms, finishes, land size and location. They often cannot see whether the home is comfortable, efficient or expensive to operate.

This creates an information gap. Efficient homes may not receive clear recognition, and poorly performing homes may not reveal their future upgrade needs until after purchase or lease.

Home energy rating disclosure is one way to close that information gap over time.

How Home Energy Ratings help

Home Energy Ratings help by turning hidden performance into clearer information. They can help households understand comfort, thermal performance, whole-of-home energy use and upgrade opportunities.

DCCEEW explains that ratings for existing homes are intended to help householders understand their home’s energy performance, identify cost-effective upgrades, improve comfort and reduce energy bills.

For the pathway definition, see What Is NatHERS Existing Homes?.

The building fabric has to come back into focus

Many energy conversations jump straight to systems: solar panels, batteries, heat pumps, air conditioning or electrification. These are important, but they work best when the building fabric is not creating unnecessary demand.

Building fabric includes insulation, glazing, shading, draught sealing, roof performance, ventilation and passive design. If those elements are weak, the home may remain uncomfortable even with better systems.

For a practical overview, see Passive Design Improvements for Existing Homes.

Retrofit sequencing is one of the hardest parts

Existing homes rarely need just one upgrade. The harder question is what should happen first.

A poor sequence can create missed opportunities, such as:

• installing a large air conditioner before reducing heat gain
• adding solar before reducing avoidable demand
• renovating walls without improving insulation
• replacing windows without reviewing shading
• sealing draughts without planning controlled ventilation
• installing systems that do not match future building fabric improvements

A rating can support better sequencing by identifying the most relevant performance issues first.

Disclosure will make existing home performance more visible

Home energy rating disclosure is likely to increase the visibility of existing home performance in the property market. Instead of relying only on appearance, buyers and renters may be able to compare homes on comfort and energy performance.

This changes the market conversation. Energy performance becomes something that can be measured, explained and improved rather than guessed after moving in.

For disclosure context, see Home Energy Rating Disclosure in Australia.

Retrofit programs need reliable home performance information

Large-scale retrofit programs are difficult without reliable information about how homes currently perform. A rating can help identify which homes have poor thermal performance, high energy demand or clear upgrade opportunities.

This could support better targeting of incentives, staged upgrade programs, landlord improvements, social housing upgrades and electrification planning.

For the next policy article in this cluster, see How Home Energy Ratings Could Support Retrofit Programs.

Why Certified Energy sees this as a long-term industry shift

Certified Energy sees existing home performance as a long-term industry shift because it connects residential energy assessment, NatHERS, disclosure, renovation advice, retrofit planning and household energy use.

The industry will need more assessors, better data collection, clearer consumer education, stronger internal linking between assessment pathways and more practical guidance for homeowners and property professionals.

The challenge is not just to rate homes. It is to help Australia understand and improve the homes people already live in.

What homeowners can do now

Homeowners do not need to solve every performance issue at once. The first step is to understand the home as it currently performs.

Useful preparation may include:

• gathering available plans or property documents
• recording comfort issues by room
• checking known insulation information
• noting window, shading and draught problems
• recording heating, cooling and hot water system details
• collecting solar or battery information
• considering a home energy rating before major upgrades

For a preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

Why are existing homes a major building performance challenge?

Existing homes are a major building performance challenge because many were built before current energy efficiency expectations. They may have poor insulation, weak glazing, limited shading, draughts, inefficient systems and comfort problems that affect energy use, bills and emissions.

Why focus on existing homes instead of only new homes?

New homes are important, but most homes people live in already exist. Improving existing homes is necessary because the current housing stock will continue to shape comfort, energy bills, emissions and household resilience for decades.

How do Home Energy Ratings help with existing homes?

Home Energy Ratings help by making existing home performance easier to understand. A rating can identify comfort issues, energy performance gaps and potential upgrade opportunities for insulation, glazing, shading, draught sealing, systems and whole-of-home energy use.

What makes existing homes difficult to improve?

Existing homes can be difficult to improve because they vary widely in age, construction, renovation history, documentation, access, climate response, systems and budget constraints. A generic upgrade pathway may not suit every home.

Why are existing homes important for emissions reduction?

Existing homes are important for emissions reduction because residential buildings contribute significantly to electricity use and carbon emissions. Improving the performance of existing homes can reduce heating, cooling and appliance energy demand over time.

Why should homeowners care about building performance?

Homeowners should care because building performance affects comfort, running costs, upgrade decisions, resilience during heat and cold, future disclosure readiness and the long-term value of home improvements.

Existing Home Performance Review

Trying to understand how an existing home performs?

Certified Energy can help clarify whether a Home Energy Rating pathway is suitable for your property, renovation planning, sale preparation, retrofit strategy or disclosure readiness.

Send property details for review

Disclosure and Market Readiness

What Home Energy Ratings May Mean for Buyers and Sellers

Home Energy Ratings may change how buyers and sellers understand the performance of existing homes.

For buyers, a rating may help make comfort, running costs and upgrade needs more visible before purchase. For sellers, a rating may help explain the value of energy upgrades that are otherwise hard to see during a short inspection.

Australia is still developing broader disclosure pathways for existing homes, so this is not about assuming every seller must already provide a rating. It is about understanding why ratings may become more important in the property market.

Why Home Energy Ratings matter in the property market

Most property listings make location, floor area, bedrooms, finishes and lifestyle features easy to see. Energy performance is much harder to understand from a listing or short inspection.

A buyer may see a renovated kitchen, fresh paint and a styled living room, but not know whether the home is hot in summer, cold in winter, poorly insulated or expensive to run. A seller may have upgraded insulation, solar, glazing or hot water, but struggle to show how those changes affect performance.

Home Energy Ratings may help make that hidden performance layer easier to understand.

What buyers may learn from a Home Energy Rating

A Home Energy Rating may give buyers a clearer view of how an existing home performs before they commit to a purchase.

Depending on the rating pathway and certificate information, buyers may better understand:

• whether the home is likely to be easier or harder to heat and cool
• whether insulation may be a concern
• whether glazing and shading affect summer comfort
• whether draughts or air leakage may contribute to discomfort
• whether major systems may be affecting energy use
• whether the home has upgrade opportunities
• whether performance should be considered in the purchase budget

For a broader explanation of rating inputs, see What Does a Home Energy Rating Actually Measure?

What sellers may gain from a Home Energy Rating

For sellers, a Home Energy Rating may help communicate performance features that are otherwise difficult to see.

This may be especially useful where the home has been upgraded with insulation, better glazing, external shading, draught sealing, efficient heating and cooling, heat pump hot water, solar, batteries or electrification improvements.

Instead of simply listing those features as inclusions, a rating may help place them within a clearer performance story for the property.

Buyers may start asking better comfort and running cost questions

Home buyers often focus on visible features because those are easiest to compare. Energy performance is less visible, but it can affect daily comfort and long-term costs.

A rating may encourage buyers to ask questions such as:

• Is the home expensive to heat or cool?
• Which rooms overheat in summer?
• Does the home stay warm in winter?
• Has insulation been installed or upgraded?
• Are windows shaded appropriately?
• Are heating and cooling systems efficient?
• What upgrades may be needed after purchase?

These questions can help buyers assess the total cost and comfort of living in the home, not only the purchase price.

Sellers may be able to make energy upgrades more visible

Some energy upgrades are hidden. Ceiling insulation, wall insulation, draught sealing, air leakage improvements and hot water upgrades may not be visible during an open home.

A rating may help sellers explain that performance work has been done, especially if supported by invoices, specifications, photos, certificates or product information.

This may become more important as buyers learn to compare homes on comfort and energy performance, not only visual presentation.

Will Home Energy Ratings affect property value?

It is too simple to say that a rating will automatically increase or decrease property value. Property value depends on many factors, including location, market conditions, land value, property type, condition, presentation and buyer priorities.

However, Home Energy Ratings may influence how buyers understand comfort, running costs and future upgrade needs. A lower-performing home may lead buyers to ask more questions about retrofit costs. A better-performing home may be easier to explain where performance upgrades are clearly documented.

The likely impact will depend on how ratings are used, how well the market understands them and how important energy performance becomes to buyers in that location.

Buyers may use ratings to plan upgrade budgets

A Home Energy Rating may help buyers understand whether upgrades should be considered after purchase. This does not mean every lower-rated home is a bad purchase. It means the buyer has clearer information about likely improvement areas.

Potential upgrade areas may include:

• ceiling, roof, wall or floor insulation
• external shading
• glazing or window performance
• draught sealing and air leakage reduction
• heating and cooling system upgrades
• hot water system replacement
• solar or battery planning
• ventilation and moisture management

For building fabric context, see Passive Design Improvements for Existing Homes.

Should sellers get a rating before listing?

Sellers may consider a Home Energy Rating before listing if they want to understand and communicate the home’s energy performance more clearly.

This may be especially relevant where the seller has already invested in upgrades or where future disclosure readiness is important. A rating can help identify what is performing well and what may still need attention.

However, sellers should first confirm whether a rating pathway is suitable, what information is needed and how the rating would be used in the sale process.

Can buyers request a rating before purchase?

A buyer may want energy performance information before purchasing a home, but a formal assessment usually requires property access and cooperation from the owner, seller or real estate agent.

In practice, this means buyers may be able to ask whether a rating is available, whether one can be arranged, or whether existing documentation can be shared. The feasibility depends on the sale process and willingness of the parties involved.

As disclosure pathways develop, buyers may become more familiar with asking for energy performance information before purchase.

How this connects to disclosure

The buyer and seller impact becomes more important as disclosure pathways develop. Disclosure means rating information may be shared with prospective buyers or renters during sale or lease.

If ratings become more common in listings or property information, buyers may start comparing homes partly on comfort and energy performance. Sellers may need to understand how to explain a rating accurately and how to support it with documentation.

For a broader explanation, see Home Energy Rating Disclosure in Australia.

What this may mean for real estate agents

Real estate agents may increasingly need to understand what a Home Energy Rating means and how it should be communicated to buyers and sellers.

NSW has already developed training and resources for the real estate sector to help agents have informed conversations about Home Energy Ratings. This reflects a broader shift: ratings are not just assessment documents, but market communication tools.

Agents do not need to become assessors, but they may need enough literacy to explain the rating process, direct clients to qualified assessors and avoid misleading performance claims.

What a Home Energy Rating does not tell buyers and sellers

A Home Energy Rating is useful, but it is not the same as a building inspection, pest inspection, valuation, structural report or electrical safety review.

It should not be used to replace due diligence on building condition, defects, compliance history or market value. Instead, it adds a performance layer that helps buyers and sellers understand energy efficiency, comfort and potential upgrades.

This distinction matters so ratings are interpreted responsibly.

What sellers can prepare before requesting a rating

Sellers who want to understand their home’s energy performance can start by gathering available property information.

Useful information may include:

• available plans or real estate floor plans
• renovation or extension history
• insulation upgrade records
• window or glazing information
• heating and cooling system details
• hot water system details
• solar or battery documentation
• photos of external elevations, windows and shading
• known comfort issues by room

For a fuller checklist, see What Information Do You Need for a Home Energy Rating?

Questions buyers may ask when a rating is available

When a Home Energy Rating is available, buyers may want to ask:

• When was the rating completed?
• Was the rating completed through an accredited pathway?
• What upgrades were recommended?
• Which upgrades have already been completed?
• Are there supporting documents for insulation, glazing, solar or systems?
• Do any rooms still overheat or feel cold?
• What would be the likely first upgrade priority?
• Does the rating reflect the home as currently presented?

These questions help buyers treat the rating as a decision-support tool, not just a number.

What this may mean over time

Over time, Home Energy Ratings may help shift the market from only valuing visible finishes to also recognising performance. This could make insulation, shading, efficient systems, electrification and whole-home upgrades easier to discuss during property transactions.

The market will need time to understand what ratings mean. Buyers will need to learn how to interpret certificates. Sellers will need to learn how to present performance information. Agents will need to learn how to discuss ratings accurately.

This is why Certified Energy sees Home Energy Ratings as part of a broader transition in how Australia understands existing home performance.

FAQs

What could Home Energy Ratings mean for buyers?

Home Energy Ratings may help buyers understand how an existing home performs for comfort, energy use and upgrade potential before purchase. A rating can help identify whether a home is likely to need insulation, glazing, shading, heating, cooling, hot water or other energy upgrades.

What could Home Energy Ratings mean for sellers?

Home Energy Ratings may help sellers communicate the energy performance of their home more clearly, especially where insulation, glazing, solar, batteries, electrification or comfort upgrades have already been completed.

Will Home Energy Ratings affect property value?

Home Energy Ratings may influence how buyers understand comfort, running costs and upgrade needs, but the effect on property value will depend on the market, property type, location, buyer priorities and how ratings are used in sale or lease disclosure.

Are sellers required to provide a Home Energy Rating?

Home Energy Rating disclosure is not yet mandatory across Australia for all existing homes. However, disclosure pathways are developing and may become more relevant as governments, real estate professionals and homeowners prepare for broader use of ratings.

Can a buyer request a Home Energy Rating before purchase?

A buyer may want energy performance information before purchase, but a formal assessment usually requires property access and the cooperation of the seller, owner or agent.

Should sellers get a Home Energy Rating before listing?

Sellers may consider a Home Energy Rating before listing if they want to better understand and communicate the home’s performance, especially where energy upgrades have been completed or future disclosure readiness is important.

Buyer and Seller Readiness

Preparing a property for sale or purchase?

Certified Energy can help clarify whether a Home Energy Rating pathway is suitable for sale preparation, buyer due diligence or future disclosure readiness.

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Disclosure and Market Readiness

Home Energy Rating Disclosure in Australia

Home energy rating disclosure is becoming an important part of Australia’s existing homes conversation.

Disclosure means that a home’s energy rating may be shared with prospective buyers or renters when a property is sold or leased. The aim is to make energy performance easier to understand before people make major property decisions.

Australia is not yet operating under one uniform mandatory disclosure scheme for all existing homes. However, national frameworks, NSW trials and real estate sector preparation show that energy performance information is likely to become more visible in the housing market.

What is home energy rating disclosure?

Home energy rating disclosure is the process of making a home’s energy performance rating available to people who may buy, rent or otherwise evaluate that property.

In practical terms, disclosure could mean that a rating is shown in sale or lease advertising, included in property information, discussed by real estate agents or made available during the transaction process.

For existing homes, this is important because energy performance has often been invisible. Buyers and renters can usually see location, price, bedrooms and finishes, but they may not know whether the home is likely to be comfortable, efficient or expensive to run.

Why disclosure is developing in Australia

Australia has a large number of existing homes that were built before current energy efficiency expectations. Many of these homes are difficult to heat, difficult to cool or expensive to run.

Without a clear rating, energy performance is hard to compare in the property market. A buyer may not know whether a home has weak insulation, unshaded glazing, air leakage, inefficient systems or upgrade opportunities.

Disclosure helps bring this information into the open so comfort and energy performance can be considered alongside location, layout and appearance.

What does disclosure at sale or lease mean?

Disclosure at sale or lease means that a home’s energy rating could be shared when the property enters the market. This may allow prospective buyers or renters to understand energy performance before making a decision.

NatHERS describes disclosure as a Home Energy Rating being shared publicly with prospective buyers or renters in sale or lease advertising of a home. This is the kind of market-facing information that can support better comparison between properties.

The exact way disclosure is implemented may differ between states and territories as governments move from trials and frameworks into rollout decisions.

Is home energy rating disclosure mandatory in Australia?

Home energy rating disclosure is not yet mandatory across Australia for all existing homes. This is the most important point to state clearly.

However, disclosure is moving from theory into practical trial and rollout planning. National framework work has been prepared, and NSW has been testing how ratings can be used and shared in the sale and lease process.

For the current mandatory-status explanation, see Are Existing Home Energy Ratings Mandatory in Australia?

The role of the national Disclosure Framework

The Home Energy Ratings Disclosure Framework provides a national approach that state and territory governments can use when introducing home energy rating disclosure at sale or lease.

This is important because property markets operate across different jurisdictions. A framework helps align the language, systems and expectations around how ratings may be used, even if each state or territory decides its own implementation pathway.

For homeowners, the framework signals that disclosure is not just a technical assessment issue. It is also a market communication issue.

The NSW Home Energy Rating trial

NSW has been one of the key states testing how home energy ratings can be integrated into the sale and lease process. The NSW and Australian governments have trialled how ratings could be used and shared when properties are sold or leased.

This work is important because disclosure is not only about creating a certificate. It also involves real estate listings, agent training, consumer understanding, data systems, assessor availability and confidence in the rating process.

For Certified Energy clients, this makes NSW a practical early market to watch as disclosure pathways continue to develop.

Why real estate sector readiness matters

For disclosure to work, real estate professionals need to understand what a Home Energy Rating means and how to communicate it accurately.

Ratings need to be presented in ways that buyers, renters, sellers and landlords can understand. A rating should not be treated as just another technical attachment. It needs to help people understand comfort, energy use and upgrade potential in plain language.

This is why agent training, listing systems and consumer education are part of the disclosure conversation.

What disclosure may mean for sellers

For sellers, disclosure may make energy performance more visible during the sale process. Homes with better thermal comfort, lower energy demand or recent upgrades may be easier to explain to prospective buyers.

This does not mean every homeowner needs to rush into upgrades immediately. But it does mean sellers may increasingly want to understand their home’s performance before listing, especially if the property has insulation, glazing, solar, electrification or comfort improvements that should be communicated clearly.

For a buyer and seller-focused article, see What Home Energy Ratings May Mean for Buyers and Sellers.

What disclosure may mean for buyers and renters

For buyers and renters, disclosure may help make comfort and running cost risks more visible before moving in.

A home that looks attractive may still be hot in summer, cold in winter or expensive to operate. Rating information can help buyers and renters ask better questions about insulation, glazing, shading, heating and cooling, hot water, solar and upgrade potential.

Disclosure may not answer every question, but it gives the market a clearer starting point than appearance alone.

What disclosure may mean for landlords

For landlords, disclosure may increase the importance of understanding rental property performance before listing or re-leasing a home.

Energy performance can affect tenant comfort, perceived property quality and future upgrade planning. A rating may help identify whether insulation, draught sealing, glazing, shading, heating, cooling or hot water upgrades should be considered.

As disclosure pathways develop, property managers and landlords may need clearer processes for rating, explaining and improving existing homes.

How NatHERS Existing Homes fits into disclosure

NatHERS Existing Homes provides a pathway for rating established dwellings. This matters because disclosure depends on reliable rating information that can be understood and shared in the market.

A Home Energy Rating can help translate a dwelling’s thermal performance, whole-of-home energy use and upgrade opportunities into information that is easier for homeowners, buyers, renters and property professionals to interpret.

For the pathway definition, see What Is NatHERS Existing Homes?.

Disclosure may change how upgrades are valued

When energy performance is invisible, upgrades can be difficult to communicate. A seller may have improved insulation, shading, hot water or solar, but buyers may not know how those changes affect comfort or running costs.

Disclosure may help make those improvements more legible. Instead of relying only on feature lists, property owners may be able to show rating information that reflects the home’s performance more clearly.

This is one reason home energy ratings could support better retrofit decisions over time.

Voluntary disclosure vs mandatory disclosure

Voluntary disclosure means property owners can choose to share a rating. Mandatory disclosure means a rating must be disclosed under a defined scheme when a property is sold or leased.

Australia is currently in a transition period. Some jurisdictions have existing disclosure arrangements, while broader national and state-level work is still developing for existing homes.

This is why language should remain careful: the direction is toward greater visibility of ratings, but requirements are not yet uniform across Australia.

What homeowners can do now

Homeowners do not need to treat disclosure as a panic deadline. But it is sensible to understand how the home performs, especially before selling, leasing, renovating or investing in upgrades.

Useful preparation may include:

• gathering available plans or property documents
• noting insulation, window or shading upgrades
• recording heating, cooling and hot water system details
• collecting solar or battery information
• identifying rooms that overheat or stay cold
• reviewing draughts, air leakage and comfort problems
• considering a home energy rating before major property decisions

For a preparation checklist, see What Information Do You Need for a Home Energy Rating?

What property professionals can do now

Real estate agents, property managers, buyer’s agents, valuers and conveyancing professionals may all need to become more familiar with home energy ratings as disclosure develops.

Useful preparation may include understanding:

• what a Home Energy Rating measures
• what a rating does not measure
• how rating certificates may be communicated
• what information sellers or landlords may need to provide
• how buyers and renters may interpret ratings
• how upgrade recommendations should be discussed responsibly

The goal is not to turn agents into assessors. It is to help the market communicate energy performance more clearly.

Why market readiness matters

Disclosure is not only a policy change. It is also a market behaviour change.

For disclosure to work well, assessors need to be available, agents need to know how to discuss ratings, homeowners need to understand the process, and buyers and renters need to know what the rating means.

This is why the current transition period is important. It allows systems, training, consumer understanding and professional practice to develop before broader disclosure becomes more common.

How disclosure may support retrofit programs

Home energy rating disclosure can also support retrofit programs by making it easier to identify where homes are underperforming and what upgrades may be most relevant.

A rating can help turn vague comfort complaints into clearer upgrade pathways. It may show whether the home needs insulation, shading, draught sealing, glazing review, system upgrades, hot water improvements, solar or a staged combination of measures.

For a broader policy and program article, see How Home Energy Ratings Could Support Retrofit Programs.

What disclosure does not mean

Disclosure does not mean every existing home instantly becomes non-compliant. It also does not mean every home must immediately be renovated to a particular standard.

A rating is information. It helps show how the home performs and where improvements may be possible. How that information is used depends on the policy setting, property purpose, owner goals and market context.

This distinction matters because homeowners may hear “disclosure” and assume it means immediate mandatory upgrades. That is not the same thing.

Why Certified Energy is watching this space closely

Certified Energy works across residential energy assessment, NatHERS, BASIX, existing home rating pathways and building performance advice. That means disclosure is not just a policy topic. It affects how homeowners, designers, builders, property professionals and assessors understand existing homes.

As home energy ratings become more visible, the market will need clear explanations that separate new-home compliance, existing-home performance, disclosure, renovation advice and retrofit planning.

The goal is not only to produce certificates, but to help people make better decisions about comfort, running costs, upgrades and long-term housing performance.

FAQs

What is home energy rating disclosure?

Home energy rating disclosure is when a home’s energy rating is shared with prospective buyers or renters, usually during the sale or lease process. It helps people understand comfort, energy performance and likely upgrade opportunities before making property decisions.

Is home energy rating disclosure mandatory in Australia?

Home energy rating disclosure is not yet mandatory across Australia. Disclosure pathways are developing, with trials, frameworks and state-led rollout activity helping governments decide how ratings may be shared at the point of sale or lease.

What does disclosure mean at sale or lease?

Disclosure at sale or lease means energy performance information could be made available when a home is advertised, sold or rented. This may help buyers and renters compare homes on comfort, running cost and energy performance.

Why is Australia developing home energy rating disclosure?

Australia is developing disclosure pathways so households can better understand the energy performance of existing homes. This may support more informed property decisions, better upgrade planning and greater market recognition of efficient homes.

How does NatHERS Existing Homes relate to disclosure?

NatHERS Existing Homes provides a pathway for rating the energy performance of established dwellings. These ratings may support future disclosure at sale or lease by giving buyers, sellers, renters and property professionals a clearer performance measure.

Should homeowners prepare for disclosure now?

Homeowners do not need to panic, but it is sensible to understand how their home performs. A home energy rating can help identify comfort issues, upgrade opportunities and performance information that may become more relevant as disclosure pathways develop.

Disclosure Readiness Review

Preparing for existing home rating disclosure?

Certified Energy can help clarify whether a Home Energy Rating pathway is suitable for your property, sale preparation, lease preparation or retrofit planning.

Send property details for review

Building Fabric

Climate Zones and Home Energy Performance

Climate is one of the most important factors in how an existing home performs.

A home in Brisbane does not need the same performance strategy as a home in Canberra. A coastal home with humid summers has different needs from an inland home with hot days, cool nights and greater temperature swings.

This is why insulation, glazing, shading, ventilation, draught sealing and passive design improvements should always be considered in relation to local climate.

Why climate zones matter

A home does not perform in isolation. It performs in a climate. Outdoor temperature, humidity, solar exposure, wind patterns, night-time cooling and seasonal variation all influence how much heating or cooling a home needs.

This means the same building feature can have different effects in different parts of Australia. A window that brings useful winter sun into a cool-climate home may create unwanted heat gain in a warm climate. A ventilation strategy that works well in a dry climate may feel less effective in humid conditions.

Climate zones help assess these differences more clearly.

Australian climate zones

YourHome uses the 8 Australian climate zones defined by the National Construction Code. These zones help describe broad climate conditions such as hot humid, warm humid, hot dry, temperate, cool temperate and alpine conditions.

NatHERS uses climate zones and weather files for rating purposes. These allow software to estimate heating and cooling needs based on local climate conditions rather than assuming every Australian home faces the same weather conditions.

For existing homes, this matters because upgrade priorities should respond to the home’s actual location, not just the age or style of the building.

How climate affects a home energy rating

A home energy rating does not only look at the house. It also considers the climate the house sits within. NatHERS star ratings consider local climate, along with the home’s design, orientation and construction materials.

This is important because heating and cooling needs are climate-dependent. A home may need strong summer heat control in one location and stronger winter heat retention in another.

For a broader explanation of what is measured, see What Does a Home Energy Rating Actually Measure?

Hot humid climates need cooling, shade and air movement

In hot humid climates, the main priority is often reducing heat gain while supporting air movement and comfort. Humidity can make passive cooling more difficult because the air may not feel cool even when it is moving.

Useful strategies may include:

• external shading for windows
• cross-ventilation where outdoor air conditions allow
• ceiling fans and air movement
• light external colours
• roof and ceiling heat control
• careful window placement and shading
• systems that manage humidity and comfort effectively

In these climates, simply adding insulation may not solve overheating unless shading, ventilation and humidity are also considered.

Hot dry climates need heat control and night-time cooling

Hot dry climates often have large temperature swings between day and night. The home may need to keep intense daytime heat out while taking advantage of cooler night air when possible.

Useful strategies may include:

• strong external shading
• roof and ceiling insulation
• controlled night ventilation or night purging
• thermal mass that is shaded and cooled properly
• draught sealing where hot air leakage is a problem
• window strategies that reduce unwanted summer heat gain

In these climates, thermal mass can help or hurt depending on whether heat is controlled during the day and released at night.

Temperate climates need balanced summer and winter strategies

Temperate climates often require both cooling and heating strategies. A home may overheat in summer but also feel cold in winter, especially if it has poor insulation, draughts or weak window performance.

Useful strategies may include:

• north-facing winter solar access where appropriate
• summer shading for exposed glazing
• ceiling, wall and floor insulation
• draught sealing with controlled ventilation
• glazing upgrades where windows are weak points
• zoning for different room uses
• efficient heating and cooling systems matched to reduced loads

In these climates, the best strategy is usually not only a summer strategy or only a winter strategy, but a balanced year-round approach.

Cool climates need heat retention and controlled solar access

In cooler climates, winter heat loss often becomes a major comfort and energy issue. Homes may need stronger focus on insulation, draught sealing, window performance and controlled solar access.

Useful strategies may include:

• ceiling, wall and floor insulation
• draught sealing and airtightness improvements
• high-performing windows and frames
• night-time window coverings
• solar access to appropriate winter-facing windows
• zoning to reduce heating demand
• efficient heating systems matched to improved building fabric

Shading still matters in summer, but winter heat retention is often a stronger driver of performance.

The same upgrade can perform differently in different climates

A common mistake is assuming that the same upgrade sequence applies everywhere. In reality, the value of each upgrade depends on the local climate and the current condition of the home.

For example, external shading may be a first priority for a home with exposed west-facing glass in a hot climate. Draught sealing and window performance may be more urgent for a cold, leaky home in a cool climate. Ventilation may be highly effective where nights are cool, but less useful where humidity remains high overnight.

Climate helps determine both the problem and the best upgrade sequence.

Climate and insulation

Insulation slows heat transfer, but the performance priority changes by climate. In hot climates, insulation can help slow heat entering through roofs, ceilings and walls. In cool climates, insulation helps reduce heat loss and keep warmth inside.

The amount, location and sequencing of insulation upgrades should respond to climate, building type and existing conditions. Ceiling insulation may be the first issue in one home, while wall or floor insulation may matter more in another.

For more detail, see Insulation in Existing Homes.

Climate, glazing and shading

Window strategy is highly climate-dependent. In some locations, the priority is keeping summer sun out. In others, the priority is reducing winter heat loss while still allowing useful solar warmth.

Orientation also matters. North, east, west and south-facing windows can perform differently depending on climate and season. This is why glazing and shading should not be selected without considering local conditions.

For more detail, see Glazing and Shading in Existing Homes.

Climate and air leakage

Air leakage affects comfort in every climate, but the consequences differ. In cool climates, draughts can make homes feel cold and increase heating demand. In hot climates, air leakage can bring hot air inside and make cooling less effective.

Humidity also matters. Airtightness improvements should always be considered with controlled ventilation so moisture and indoor air quality are managed properly.

For more detail, see Draught Sealing and Air Leakage in Existing Homes.

Climate and passive design improvements

Passive design improvements work best when they respond to climate. A cooling-focused strategy may prioritise shading, ventilation and roof heat reduction. A heating-focused strategy may prioritise insulation, airtightness and winter solar access.

Mixed climates need balance. Blocking all sun may reduce summer heat but remove useful winter warmth. Sealing draughts may improve comfort but needs controlled ventilation. Adding insulation may help both seasons but should be coordinated with shading and ventilation.

For more detail, see Passive Design Improvements for Existing Homes.

Climate and summer overheating

Overheating can occur in many Australian climates, but the causes and solutions vary. In hot dry regions, daytime heat gain and night-time cooling opportunities may be central. In humid climates, shade and air movement may be critical but ventilation may not always feel cooling if outdoor air remains warm and humid.

In temperate regions, overheating may be linked to west-facing glazing, poor shading, roof heat and homes that cannot release heat overnight. In cooler climates, overheating can still occur in upper-storey rooms or poorly shaded spaces during heatwaves.

For more detail, see Why Older Australian Homes Overheat in Summer.

How a home energy rating can support climate-appropriate upgrades

A home energy rating can help identify whether the home’s performance issues are mainly driven by climate exposure, building fabric, systems, orientation or a combination of these factors.

This matters because upgrade sequencing should not be generic. A climate-appropriate pathway may prioritise shading before glazing, insulation before system replacement, draught sealing before heating upgrades, or ventilation before additional cooling capacity.

For pathway context, see NatHERS Existing Homes.

Renovation is the time to respond to climate

Renovation is often the best time to improve climate response because windows, shading, roof works, insulation, ventilation and systems may already be changing.

If climate is considered too late, the project may lock in design decisions that are difficult or expensive to correct later, such as large unshaded west-facing glazing, missed insulation opportunities or heating and cooling systems that do not match the improved building fabric.

For renovation context, see Existing Home Energy Rating vs Renovation Energy Assessment.

Common mistakes when climate is ignored

Common mistakes include:

• using the same window strategy on every elevation
• copying upgrades from a different climate zone
• blocking useful winter sun in a cool or mixed climate
• forgetting humidity when planning ventilation
• adding cooling before reducing summer heat gain
• adding heating before addressing draughts and insulation
• installing solar before reducing unnecessary heating and cooling demand
• assuming one upgrade will solve both summer and winter comfort

Climate-aware assessment helps avoid upgrades that look sensible in general but are not well matched to the specific home.

What information helps a climate-aware home energy review?

Before requesting a home energy rating or upgrade review, it helps to prepare information about the home and its comfort patterns.

Useful information may include:

• property address
• available floor plans or real estate plans
• photos of each side of the home
• photos of windows, shading and roof form
• known insulation information
• rooms that overheat or stay cold
• time of day when comfort issues occur
• heating and cooling system details
• renovation or extension history
• planned upgrades or renovation scope

For a full checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

Why do climate zones matter for home energy performance?

Climate zones matter because a home’s heating, cooling, insulation, glazing, shading and ventilation needs depend on local climate. A strategy that works well in a cool climate may not be right for a hot humid, hot dry or mixed climate.

How many climate zones does Australia have?

YourHome uses the 8 Australian climate zones defined by the National Construction Code. NatHERS also uses climate zones and weather files to calculate thermal performance more specifically for rating purposes.

Does NatHERS use climate zones?

Yes. NatHERS ratings consider local climate, along with the home’s design, orientation, construction materials and other features, when calculating the thermal performance of a home.

Do different climate zones need different home upgrades?

Yes. Homes in different climate zones may need different upgrade priorities. Hot climates may focus more on cooling, shading and ventilation, while cooler climates may focus more on insulation, airtightness, glazing and winter heat retention.

Can the same home perform differently in different climates?

Yes. The same home design can perform differently in different climates because heating and cooling loads, sun exposure, humidity, ventilation needs and seasonal comfort conditions all change by location.

Can a home energy rating help identify climate-appropriate upgrades?

Yes. A home energy rating can help identify whether insulation, glazing, shading, ventilation, draught sealing, roof performance or system upgrades are most relevant for the home’s climate and current performance.

Home Energy Rating Review

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Building Fabric

Passive Design Improvements for Existing Homes

Passive design is not only for new homes. Existing homes can often be improved by helping the building work better with its climate.

In an existing home, passive design improvements may include shading, insulation, draught sealing, ventilation, glazing upgrades, roof heat reduction, zoning and better renovation sequencing.

The goal is to reduce unwanted heat gain, reduce heat loss, improve comfort and lower the amount of mechanical heating and cooling the home needs to feel liveable.

What passive design means for an existing home

Passive design is the practice of designing or improving a home so it works with the local climate rather than fighting against it. It uses orientation, shading, insulation, ventilation, glazing and thermal behaviour to support comfort.

In a new home, passive design can be built into the layout from the start. In an existing home, the process is different. The dwelling already has its orientation, roof form, windows, materials and room layout. The task is to identify which existing features are helping performance and which are making the home harder to live in.

This makes passive design for existing homes a retrofit and upgrade strategy, not a blank-page design exercise.

Why passive design matters in existing homes

Many existing Australian homes are uncomfortable because the building fabric is doing too little work. Heat enters too easily in summer, escapes too quickly in winter, or moves through gaps and weak points before heating and cooling systems can respond effectively.

When that happens, homeowners often respond by adding more mechanical systems, larger air conditioners, extra heaters or solar panels. These can be useful, but they do not always solve the underlying comfort problem.

Passive design improvements can reduce the load on those systems by improving the way the home handles heat, sun, air and comfort in the first place.

Start with how the home performs now

The best passive design improvements start with the existing home, not with a generic product list. A home that overheats through west-facing windows needs a different strategy from a home that loses winter heat through draughty floors and weak ceiling insulation.

Useful questions include which rooms are uncomfortable, when the problem occurs, which windows receive sun, whether the home cools down overnight, whether draughts are present and whether insulation is known or uncertain.

For more detail on assessment inputs, see What Does a Home Energy Rating Actually Measure?

1. Improve shading before heat enters the home

Shading is one of the most important passive design improvements for homes that overheat. It works by reducing unwanted sun before it passes through windows and becomes heat inside the room.

Useful shading upgrades may include:

• eaves or roof overhangs
• awnings
• external blinds
• operable shutters
• screens or louvres
• verandahs or pergolas
• adjustable shading for east and west windows
• site-specific shading from neighbouring structures or landscape elements

For a deeper explanation, see Glazing and Shading in Existing Homes.

2. Review glazing where windows are a weak point

Windows can create both summer heat gain and winter heat loss. In some homes, the main issue is not only the glass itself, but the combination of window size, orientation, frame type, air leakage and lack of shading.

Glazing upgrades may be useful where existing windows perform poorly, but they should be reviewed carefully. Replacing all windows is not always the first or most cost-effective step. Sometimes shading, sealing or selective replacement may have a stronger impact.

The best glazing strategy depends on climate, orientation, comfort complaints and the renovation pathway.

3. Improve insulation where the building fabric is weak

Insulation helps slow heat movement through ceilings, roofs, walls and floors. In existing homes, insulation may be missing, compressed, damaged, inconsistent or difficult to verify.

Areas worth reviewing include:

• ceiling insulation
• roof insulation
• wall insulation
• floor insulation
• insulation around extensions or additions
• insulation disturbed by previous trades or renovations

For more detail, see Insulation in Existing Homes.

4. Reduce draughts and uncontrolled air leakage

Draught sealing helps reduce uncontrolled air movement through gaps, cracks and penetrations. This can improve comfort by helping the home hold warm or cool air more effectively.

Common leakage points include:

• external doors
• windows and sliding doors
• open fireplaces and chimneys
• wall vents
• floorboard gaps
• ceiling penetrations
• downlights and exhaust fans
• junctions between old and renovated areas

Draught sealing should always be considered with controlled ventilation. For more detail, see Draught Sealing and Air Leakage in Existing Homes.

5. Improve controlled ventilation and heat release

Ventilation can help an existing home release heat when outdoor conditions are cooler than inside. This is especially useful in the evening, overnight or early morning in climates where night purging is possible.

Some homes overheat because heat enters during the day and becomes trapped. Others have windows that do not support cross-ventilation, security concerns that limit night ventilation, or internal layouts that block air movement.

A passive design review can help identify whether ventilation needs to be improved, controlled or balanced with draught sealing and indoor air quality requirements.

6. Reduce roof and ceiling heat transfer

Roofs can absorb significant summer heat. If the roof space becomes very hot and ceiling insulation is weak, heat can move into rooms below and make the home uncomfortable late into the day.

Potential strategies may include:

• improving ceiling insulation
• reviewing roof insulation
• considering roof colour during replacement
• reviewing roof space ventilation
• reducing radiant heat transfer where appropriate
• coordinating roof works with solar, insulation and services upgrades

Roof-related upgrades are often best reviewed before major roof replacement, solar installation or ceiling works are finalised.

7. Use zoning to manage comfort more effectively

Zoning means managing different parts of the home separately. In existing homes, some rooms may be used all day, while others are only used at night or occasionally.

Passive zoning may involve doors, curtains, internal layouts, room use patterns, window operation, shading and heating or cooling strategy. It can help prevent the whole home from being conditioned when only certain areas need comfort control.

Zoning is especially useful in older homes with uneven comfort between original rooms, extensions and upper-level spaces.

8. Reduce external heat around the home

The area around the home can affect internal comfort. Dark paving, unshaded hard surfaces, heat-reflective walls and exposed outdoor areas can raise the temperature near windows and walls.

Possible improvements may include:

• reducing dark hard surfaces near windows
• adding shaded outdoor areas
• using lighter external finishes where appropriate
• reviewing heat-reflective boundary conditions
• coordinating shading with outdoor use and summer comfort

External heat control should be considered alongside glazing, shading, ventilation and roof performance.

Passive design should support both summer and winter comfort

A good passive design strategy should not only solve one season while making another worse. A home that is shaded too heavily may lose useful winter sun. A home that is sealed without ventilation may create moisture or indoor air quality risks. A home with more insulation may still need shading and ventilation to manage summer heat.

Winter-focused improvements may include insulation, draught sealing, improved window performance, controlled solar access, zoning and curtains or window coverings that reduce heat loss at night.

The best approach depends on climate zone, orientation, building fabric and the way the home is used.

Why passive design should often come before new systems

Solar, batteries, efficient appliances and modern heating or cooling systems can all be valuable. But they are more effective when the home itself is not working against them.

If a home has high heat gain, poor insulation or major air leakage, systems may need to be larger, run longer or use more energy than necessary. Passive design improvements can reduce the demand before systems are selected or upgraded.

This does not mean systems are unimportant. It means building fabric and systems should be planned together.

Renovation is the best time to plan passive design improvements

Renovation creates opportunities that may not be available later. Walls, roofs, ceilings, floors, windows and services may become accessible. This can make it easier to improve insulation, sealing, glazing, shading, ventilation and system strategy at the same time.

If passive design is considered too late, the project may lock in large unshaded windows, poor orientation responses, missed insulation opportunities or heating and cooling systems that do not match the improved building fabric.

For renovation context, see Existing Home Energy Rating vs Renovation Energy Assessment.

How a home energy rating can help

A home energy rating can help identify which passive design issues are affecting the home. The assessment may show whether comfort problems are linked to glazing, shading, insulation, draughts, roof heat, ventilation, orientation, climate or installed systems.

This can help homeowners avoid guessing. Instead of starting with the most visible or heavily marketed upgrade, the rating can support a more considered sequence of improvements.

For more detail, see What Does a Home Energy Rating Assessor Look For?

Common passive design mistakes in existing home upgrades

Common mistakes include:

• adding air conditioning before reducing heat gain
• installing solar before reviewing high heating and cooling demand
• replacing windows without reviewing shading
• insulating without considering ventilation and moisture
• sealing draughts without controlled ventilation
• using the same glazing strategy on every elevation
• blocking useful winter sun with poorly planned shading
• missing insulation opportunities during renovation
• treating each upgrade as separate rather than connected

A better approach is to assess the home as a system before choosing the upgrade sequence.

What information helps a passive design review?

Before requesting a home energy rating or passive design review, it helps to prepare information that shows how the home behaves and what is already known.

Useful information may include:

• property address
• available floor plans or real estate plans
• photos of each side of the home
• photos of major windows and shading
• known insulation information
• renovation or extension history
• heating and cooling system details
• known comfort issues by room
• rooms that overheat or stay cold
• planned renovation or upgrade scope

For a full checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

What are passive design improvements for existing homes?

Passive design improvements are upgrades that help an existing home use climate, orientation, shading, insulation, ventilation and building fabric more effectively before relying heavily on mechanical heating and cooling.

Can passive design be added to an existing home?

Yes. While passive design is easiest to include in new homes, existing homes can often be improved through shading, insulation, draught sealing, ventilation, glazing upgrades, roof colour, external heat reduction and better renovation planning.

What passive design upgrades help with summer overheating?

Summer overheating may be improved through external shading, better glazing choices, roof and ceiling insulation, controlled ventilation, night purging, draught sealing, lighter external surfaces and reducing heat around exposed windows.

What passive design upgrades help in winter?

Winter comfort may be improved through insulation, draught sealing, better window performance, controlled solar access, thermal zoning, curtains or window coverings, and reducing uncontrolled heat loss through gaps and weak building fabric.

Should passive design improvements happen before solar or new systems?

Often, yes. Passive design improvements can reduce heating and cooling demand before new systems are sized or installed. Solar, batteries and efficient appliances are valuable, but they do not automatically fix poor comfort or weak building fabric.

Can a home energy rating help identify passive design upgrades?

Yes. A home energy rating can help identify whether passive design issues such as glazing, shading, insulation, air leakage, ventilation, roof heat or orientation are affecting the home’s performance.

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Summer Comfort

Why Older Australian Homes Overheat in Summer

Older Australian homes often overheat because the building fabric was not designed or upgraded for today’s comfort expectations.

The cause is rarely one single issue. Summer overheating usually comes from a combination of direct sun on windows, poor shading, weak insulation, roof heat, air leakage, limited ventilation, orientation, climate and the way heat is stored inside the home.

A home energy rating can help separate the visible symptom from the underlying performance problem, so upgrades can be planned in a better sequence.

Why overheating is common in older Australian homes

Many older Australian homes were designed for different expectations, different materials, different appliance use and different comfort standards. Some relied on verandahs, high ceilings, lightweight construction or natural ventilation. Others were built before strong attention was given to insulation, airtightness, window performance or orientation.

Over time, renovations may also change how a home behaves. A new room may add large windows without enough shading. A garage conversion may have weak insulation. A rear extension may trap afternoon heat. A roof replacement may change heat gain without improving ceiling insulation.

This means summer overheating is often the result of many small decisions rather than one obvious failure.

Direct sun on glazing is a major cause of overheating

Windows are one of the main ways summer heat enters a home. When direct sun hits glass, heat can build quickly inside the room, especially if the glass is large, unshaded or facing east or west.

YourHome describes shading of glazing as a critical part of passive cooling because glazing is a major source of heat gain through direct radiation and conduction.

For a deeper explanation, see Glazing and Shading in Existing Homes.

West-facing rooms often become the hottest rooms

West-facing rooms can be difficult to keep cool because they receive low-angle afternoon sun when the day is already hot. This heat can enter through windows and continue affecting the room into the evening.

Simple eaves often do not shade low-angle west sun well. External screens, adjustable shading, vertical shading, planting, neighbouring built form or glazing improvements may need to be considered depending on the home.

This is why two rooms in the same house can feel completely different in summer.

Poor shading allows heat in before cooling begins

Air conditioning often deals with heat after it has entered the home. Shading helps reduce that heat before it passes through the glass.

This distinction matters. Internal blinds and curtains can help with comfort and glare, but external shading is often more effective for summer heat because it blocks or reduces sun before it reaches the glazing.

In many existing homes, improving shading may be a practical first step before replacing every window or increasing cooling capacity.

Roof heat can drive indoor discomfort

Roofs receive strong solar exposure during summer. If the roof space becomes very hot and the ceiling is poorly insulated, heat can move into the rooms below.

This is one reason bedrooms, upper-storey spaces and rooms directly under roof areas can become uncomfortable late in the day. The roof may keep transferring heat into the home after outdoor conditions begin to cool.

Ceiling insulation, roof ventilation, roof colour, radiant barriers and construction type can all affect how much heat is transferred into the dwelling.

Weak insulation can allow heat to enter too quickly

Insulation helps slow heat movement through ceilings, roofs, walls and floors. If insulation is missing, compressed, damaged or inconsistent, the home may gain heat more quickly during summer.

However, insulation is not a complete overheating solution on its own. If the home has unshaded glass or poor ventilation, insulation may slow the heat movement but not solve the main cause of summer discomfort.

For more detail, see Insulation in Existing Homes.

Air leakage can bring unwanted heat inside

In summer, uncontrolled air leakage can allow hot outdoor air to enter the home. This can make rooms harder to cool, especially during hot windy conditions or when there are leakage paths through roof spaces, wall cavities or subfloors.

Draught sealing can help reduce uncontrolled air movement, but it should be balanced with controlled ventilation. A better-performing home is not simply sealed shut. It needs to manage fresh air intentionally.

For more context, see Draught Sealing and Air Leakage in Existing Homes.

Poor ventilation can trap heat inside

Ventilation helps remove heat when outdoor air is cooler than indoor air. This can be especially useful in the evening, overnight or early morning when the home needs to release stored heat.

Some existing homes have windows that do not support good cross-ventilation, rooms that trap heat, security concerns that limit night ventilation, or layouts where air movement is blocked by doors and internal walls.

Ventilation alone cannot always solve overheating, but without a way to release heat, other upgrades may not perform as well as expected.

Thermal mass can help or hurt, depending on how it is managed

Thermal mass refers to materials that can absorb and store heat, such as concrete, brick, stone or tiles. In the right conditions, thermal mass can help moderate indoor temperature swings.

But thermal mass needs to be protected from unwanted summer sun and cooled when outdoor conditions allow. YourHome recommends protecting thermal mass from summer sun with shading and insulation, and ensuring cool night breezes and air currents can draw out stored energy.

If thermal mass absorbs heat all day and cannot release it overnight, the home may feel hot well into the evening.

Dark roofs and hard surfaces can add heat load

External materials can affect how much heat is absorbed around the home. Dark roof surfaces, dark paving, unshaded hard surfaces and heat-reflective neighbouring walls can all contribute to higher temperatures around the building.

This can be especially noticeable in dense urban areas or around homes with limited shade and large areas of concrete, tiles or paving near windows.

External heat exposure should be considered alongside internal comfort complaints.

Air conditioning may not fix the underlying problem

Air conditioning can cool a room, but it does not remove the underlying cause of overheating. If heat keeps entering through unshaded glass, a hot roof space, weak insulation or air leakage, the system may need to run harder and longer.

This can lead to higher energy use and uneven comfort. Some rooms may cool quickly, while others remain hot or reheat soon after the system turns off.

Building fabric upgrades can reduce cooling demand before mechanical systems need to respond.

How a home energy rating can help explain overheating

A home energy rating can help identify which parts of the home are contributing to summer discomfort. The issue may be glazing, shading, insulation, roof heat, air leakage, ventilation, orientation, climate or a combination of several factors.

This matters because the best solution is not always the most obvious one. A hot room may need shading before new glazing. A hot upper floor may need ceiling or roof review. A draughty home may need sealing before system replacement.

For more detail on assessment inputs, see What Does a Home Energy Rating Assessor Look For?

What should be reviewed first?

The right starting point depends on the home, but overheating reviews often begin with the rooms where discomfort is most obvious.

Useful questions include:

• Which rooms overheat first?
• Do they face west, east or north?
• Are the windows externally shaded?
• Is the ceiling or roof well insulated?
• Does the room cool down overnight?
• Is there cross-ventilation?
• Are there draughts or air leakage paths?
• Has the room been extended or renovated?
• Does heat build up again quickly after cooling?

These questions help guide the assessment toward the real cause of overheating.

Renovation is a key opportunity to solve overheating

Overheating is often easiest to address when a home is being renovated. Window changes, roof works, insulation upgrades, shading, external works and services replacement can all affect summer comfort.

If energy performance is reviewed too late, the design may already have locked in large unshaded glazing, poor ventilation or missed opportunities to improve insulation and airtightness.

For renovation context, see Existing Home Energy Rating vs Renovation Energy Assessment.

FAQs

Why do older Australian homes overheat in summer?

Older Australian homes may overheat because of unshaded glazing, poor roof or ceiling insulation, air leakage, limited ventilation, heat stored in building materials, dark roofs, west-facing windows and design features that do not respond well to the local climate.

Can poor shading make an older home overheat?

Yes. Poor shading can allow direct summer sun to enter through windows and glazed doors, increasing indoor temperatures and cooling demand. External shading is often important because it reduces heat before it passes through the glass.

Does insulation help with summer overheating?

Insulation can help slow heat entering through the roof, ceiling, walls or floors, but it is not a complete overheating solution on its own. It works best with shading, ventilation, draught sealing and appropriate glazing.

Why do west-facing rooms get so hot?

West-facing rooms often overheat because they receive low-angle afternoon sun when outdoor temperatures are already high. This sun can be difficult to shade with simple eaves and can drive significant heat gain through windows.

Can ventilation reduce overheating?

Ventilation can help reduce overheating when cooler outside air is available, especially through cross-ventilation or night purging. However, ventilation alone may not solve overheating if the home continues to gain too much heat during the day.

Can a home energy rating help explain overheating?

Yes. A home energy rating or assessment can help identify whether overheating is linked to glazing, shading, insulation, air leakage, ventilation, roof heat, orientation, climate or a combination of building fabric issues.

Home Energy Rating Review

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Building Fabric

Draught Sealing and Air Leakage in Existing Homes

Draughts are one of the most noticeable comfort problems in existing homes.

A home can have insulation, new appliances and even solar panels, but still feel uncomfortable if uncontrolled air leaks allow cold air in during winter or hot air in during summer.

Draught sealing is the process of reducing uncontrolled air movement through gaps, cracks and openings in the building fabric. It can improve comfort and energy performance, but it needs to be balanced with healthy, controlled ventilation.

Why draughts matter in existing homes

Many existing Australian homes were built with less attention to airtightness than modern high-performance buildings. Over time, gaps can also appear around windows, doors, floors, roof spaces, service penetrations and renovation junctions.

When uncontrolled air moves through the home, heating and cooling systems may need to work harder. Rooms can feel uncomfortable even when the thermostat suggests the home should be warm or cool.

This is why draught sealing can be one of the most practical building fabric upgrades to consider before replacing systems or adding more technology.

What is air leakage?

Air leakage is uncontrolled air movement through unintended gaps in the building fabric. It is different from intentional ventilation, which is planned and controlled.

Common air leakage paths include:

• gaps around external doors
• gaps around windows
• open fireplaces and chimneys
• old wall vents
• exhaust fans without proper backdraft control
• floorboard gaps
• skirting board gaps
• ceiling penetrations
• downlights and service penetrations
• plumbing and electrical penetrations
• junctions between old and renovated areas

These leakage paths can be small individually, but together they can significantly affect comfort and energy performance.

Draught sealing is not the same as insulation

Draught sealing and insulation both affect comfort, but they solve different problems.

Insulation slows heat transfer through ceilings, roofs, walls and floors. Draught sealing reduces uncontrolled air movement through gaps and cracks. A home can be insulated but still draughty, or sealed but still poorly insulated.

For that reason, both should be considered as part of the whole building fabric. For more context, see Insulation in Existing Homes.

How draughts affect comfort

Draughts often create discomfort before they show up clearly in energy data. A room may feel cold around the ankles, uncomfortable near windows or doors, or difficult to heat evenly.

In summer, air leakage can allow hot outside air into the home, especially during heatwaves or windy conditions. In winter, cold air can enter while heated indoor air escapes, making the home feel colder than expected.

This can lead to higher heating and cooling use because occupants keep adjusting systems to compensate for the leaky building fabric.

How air leakage affects energy performance

Air leakage can increase heating and cooling demand because conditioned air is lost and outdoor air enters the home. This can make systems run longer or work harder to maintain comfort.

The effect depends on climate, wind exposure, building type, occupant behaviour and where the leakage occurs. In some homes, a few major leakage paths may have more impact than many small gaps.

A home energy rating or assessment can help identify whether air leakage is likely to be part of the performance problem.

Common draught sources in existing homes

Common draught sources include:

• external doors without seals
• sliding doors and old window frames
• gaps around skirting boards
• old floorboards or subfloor gaps
• open fireplaces and unused chimneys
• wall vents and legacy ventilation openings
• ceiling penetrations
• recessed downlights
• exhaust fans
• rangehoods
• plumbing and electrical penetrations
• junctions around extensions or additions

A useful review looks for patterns rather than assuming every gap has the same impact.

Doors and windows are common leakage points

Older doors and windows often leak air around seals, frames, tracks and joints. Sliding doors, timber windows, poorly fitted external doors and older aluminium frames can all contribute to draughts.

This is why glazing and draught sealing should often be reviewed together. A window may have poor thermal performance because of the glass, the frame, the seal or a combination of these issues.

For more context, see Glazing and Shading in Existing Homes.

Fireplaces, vents and exhaust openings can leak air

Open fireplaces, unused chimneys, old wall vents, exhaust fans and rangehoods can allow air movement between inside and outside. In some homes, these can be major leakage paths.

The correct response depends on whether the opening is still required for safety, appliance operation, combustion air or ventilation. Some openings can be sealed or improved. Others may need to remain functional or be replaced with controlled ventilation.

This is why draught sealing should be assessed carefully rather than handled as a blanket “seal everything” exercise.

Ceiling, floor and service penetrations can matter

Air leakage is not only around doors and windows. It can also occur through ceiling penetrations, gaps around downlights, exhaust fans, plumbing pipes, electrical conduits, floorboards and subfloor openings.

These leakage paths can connect living spaces to roof spaces, wall cavities, subfloors or outside air. In windy conditions, the effect can become more noticeable.

When sealing these areas, safety and compliance matter. Electrical, exhaust, combustion and ventilation requirements should not be compromised.

Renovation junctions can create air leakage

Existing homes often contain junctions between old and new construction. Extensions, converted garages, roof additions and reconfigured rooms can create gaps or inconsistent sealing where materials meet.

These junctions can be difficult to diagnose because the problem is sometimes hidden behind finishes or located at the boundary between building stages.

Renovation is often a valuable time to address air leakage because walls, ceilings, floors and services may already be accessible.

Airtightness needs controlled ventilation

A more airtight home is not the same as a poorly ventilated home. The goal is to reduce uncontrolled air leakage while still providing healthy, intentional ventilation.

This distinction is important because sealing gaps without considering ventilation can increase moisture, condensation and indoor air quality risks. Bathrooms, kitchens, laundries and bedrooms may all need appropriate ventilation strategies.

A good retrofit approach is not simply “make the home as sealed as possible.” It is to reduce unwanted leakage and manage fresh air deliberately.

How air leakage relates to a home energy rating

A home energy rating may consider air leakage, sealing quality or draught-related features depending on the assessment pathway. In some contexts, formal airtightness testing may provide more precise information. In others, assessor observations and available evidence may guide the review.

Air leakage is part of the wider building fabric picture. It interacts with insulation, glazing, shading, ventilation, heating and cooling systems.

For a broader explanation, see What Does a Home Energy Rating Actually Measure?

How an assessor may review draughts and air leakage

An assessor may look for visible or likely air leakage paths as part of the broader home energy rating process. The level of detail depends on the assessment pathway and whether formal testing is required or available.

Useful information may include:

• rooms that feel draughty
• doors or windows that rattle in wind
• visible light around door or window gaps
• known fireplace, chimney or vent issues
• areas where curtains move even when windows are closed
• renovation junctions that feel leaky
• ceiling or floor penetrations
• rooms with moisture, condensation or ventilation concerns

For more context, see What Does a Home Energy Rating Assessor Look For?

Renovation is often the best time to address air leakage

Draught sealing is often easier when renovation works are already exposing walls, ceilings, floors, windows, doors or services. Once finishes are complete, some leakage paths become harder to reach.

This is especially relevant for extensions, roof works, window replacement, floor repairs, kitchen and bathroom renovations, services upgrades and whole-home retrofits.

For renovation context, see Existing Home Energy Rating vs Renovation Energy Assessment.

What should not be sealed without advice?

Some openings may be required for ventilation, appliance safety, combustion air or moisture management. These should not be blocked without proper advice.

Be careful with:

• gas appliance ventilation
• combustion air openings
• bathroom, kitchen and laundry exhaust systems
• subfloor ventilation
• roof space ventilation
• moisture-affected areas
• heritage building elements
• areas with mould or condensation issues

The goal is controlled performance, not unsafe sealing.

What information helps a draught and air leakage review?

Before requesting a home energy rating or upgrade review, it can help to record where draughts are felt and when they occur.

Useful information may include:

• rooms that feel draughty
• photos of doors, windows and visible gaps
• notes on fireplaces, vents or exhaust fans
• areas that feel cold near floors or skirtings
• rooms with condensation or moisture concerns
• renovation history
• known window or door replacement history
• any existing energy or comfort reports

For a full preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

Why does draught sealing matter in existing homes?

Draught sealing matters because uncontrolled air leakage can make an existing home feel cold, hot, draughty or difficult to condition. Sealing gaps can improve comfort and reduce heating and cooling demand when done with appropriate ventilation.

What is air leakage in a home?

Air leakage is uncontrolled air movement through gaps, cracks and penetrations in the building fabric. It can occur around doors, windows, floors, ceilings, exhaust fans, downlights, chimneys, vents, service penetrations and poorly sealed construction joints.

Does a home energy rating assess draughts or air leakage?

A home energy rating may consider air leakage, sealing quality or draught-related features depending on the assessment pathway, available information and whether formal testing or assessor observations are used.

What are common sources of draughts in existing homes?

Common draught sources include gaps around doors and windows, open fireplaces, wall vents, exhaust fans, floorboard gaps, ceiling penetrations, downlights, plumbing penetrations, poorly sealed skirtings and gaps between old and renovated areas.

Is draught sealing the same as insulation?

No. Insulation slows heat transfer through building elements, while draught sealing reduces uncontrolled air movement through gaps and cracks. Both can affect comfort and energy performance, but they solve different problems.

Can a home be sealed too tightly?

Yes. Airtightness should be balanced with controlled ventilation. If a home is sealed without adequate ventilation, moisture, condensation, indoor air quality and mould risks may increase.

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Building Fabric

Glazing and Shading in Existing Homes

Glazing and shading can strongly influence how an existing home feels throughout the year.

Windows bring light, outlook, ventilation and winter solar warmth into a home. But they can also create summer overheating, winter heat loss, glare and rooms that are difficult to heat or cool.

For existing homes, the question is not only whether the windows are single or double glazed. It is also whether the glass is facing the right direction, whether it is shaded at the right time, and how the window system works with insulation, ventilation and heating or cooling.

Why glazing and shading matter in existing homes

Windows are often one of the weakest parts of the building fabric. They usually perform differently from insulated walls, roofs and floors because glass allows light, heat and solar radiation to pass through in ways opaque building elements do not.

In winter, windows can lose heat and make nearby rooms feel cold. In summer, windows can admit unwanted solar heat and create overheating. If shading is poor, the room may become uncomfortable before the air conditioner is even switched on.

This is why glazing and shading should be reviewed together rather than treated as separate issues.

What does glazing mean?

Glazing refers to the glass in windows, doors and skylights, as well as the wider window system that affects performance. In practical assessment, window performance is influenced by the glass, frame, seals, orientation, size and exposure.

Common glazing types include single glazing, double glazing, low-e glass, tinted glass and other performance glass products. The right choice depends on the home, climate, orientation and whether the main problem is summer heat gain, winter heat loss, glare or comfort near the glass.

For a home energy rating, glazing is not only a product choice. It is part of how the building performs as a whole.

What does shading mean?

Shading refers to anything that controls direct sun on windows, glazing and sometimes walls or outdoor areas. It can be fixed, adjustable, external, internal or created by nearby structures.

Common shading elements include:

• eaves and roof overhangs
• awnings
• external blinds
• screens and shutters
• verandahs and pergolas
• balconies and upper floors
• nearby buildings or boundary structures
• internal blinds or curtains, where relevant to comfort

External shading is often especially effective because it reduces direct sun before it passes through the glass.

Two important glazing concepts: U-value and SHGC

Window performance is often described through two important concepts: U-value and Solar Heat Gain Coefficient, or SHGC.

U-value relates to how readily heat conducts through the window system. A lower U-value generally means the window is better at resisting heat transfer. SHGC relates to how much solar heat the glazing allows into the home from direct sunlight.

This matters because a window that performs well for winter heat loss may not automatically solve summer heat gain. The best window strategy depends on orientation, climate and shading.

Orientation changes how windows perform

The same window can behave differently depending on which direction it faces. In Australia, north, east, west and south-facing glazing can create very different comfort outcomes.

North-facing windows can often be shaded more predictably with well-designed horizontal shading. East and west-facing windows can be more difficult because low-angle morning and afternoon sun can penetrate deeply and create heat gain. South-facing windows may receive less direct sun in many locations but can still contribute to heat loss.

This is why a window upgrade should not simply use the same glazing and shading approach on every elevation.

Glazing, shading and summer overheating

Summer overheating is often driven by direct sun on glass. Once solar heat enters a room, it can be difficult to remove without mechanical cooling, especially if the room has poor ventilation or the home stores heat into the evening.

Good shading can reduce unwanted sun before it reaches the glass. In many existing homes, shading can be a more practical first step than replacing every window, especially where the main issue is exposed summer sun.

However, the right solution depends on which windows are causing the problem, how the home is ventilated and what other building fabric issues are present.

Glazing and winter heat loss

Windows can also be a major source of winter heat loss. Rooms near poorly performing windows may feel cold, even when the heating system is running.

Double glazing or other higher-performing glazing systems can help reduce heat loss, but the benefit depends on the whole window system, frame type, installation quality, air leakage and how the room is used.

Window upgrades should therefore be assessed alongside draught sealing, insulation and heating system strategy.

External shading usually works before heat enters the home

External shading is often powerful because it blocks or reduces direct sun before it passes through the glass. Examples include eaves, awnings, external blinds, screens, shutters and verandahs.

Internal blinds and curtains can improve comfort and privacy, and some products can help reduce heat movement. However, once sunlight has already passed through the glass, much of the heat is already inside the room.

For overheating problems, external shading is often worth reviewing before assuming the only answer is air conditioning or full window replacement.

Fixed shading and adjustable shading

Fixed shading includes elements such as eaves, roof overhangs, awnings, pergolas and verandahs. These can be durable and low-maintenance, but they need to be designed carefully for orientation and season.

Adjustable shading includes external blinds, shutters, operable louvres and some screen systems. These can provide more flexibility because they can respond to season, weather, time of day and occupant preference.

In existing homes, adjustable shading can sometimes be a practical retrofit option where fixed shading is difficult to add or where different seasons require different levels of solar access.

How glazing and shading affect a home energy rating

A home energy rating may consider glazing and shading because they influence heating and cooling demand. Window size, location, orientation, glass type, frame type and external shading can all affect the result.

In an existing home, some window information may be easy to identify. Other details may require documentation, product labels, site observations or reasonable assumptions under the relevant assessment pathway.

For more detail on what assessors review, see What Does a Home Energy Rating Assessor Look For?

Glazing and shading do not work alone

Window upgrades can be valuable, but they should not be treated as the only performance measure. A home with better glazing may still perform poorly if insulation is missing, air leakage is high or shading is inadequate.

Likewise, shading can reduce summer heat gain but may not solve winter heat loss, draughts, poor ventilation or inefficient heating and cooling systems.

For that reason, glazing and shading should be assessed as part of the whole-home performance pathway.

Renovation is often the best time to review glazing and shading

Window and shading decisions can be difficult to change later. If a renovation involves new openings, replacement windows, facade changes, decks, pergolas or external works, glazing and shading should be considered early.

This can help avoid situations where a room is newly renovated but still overheats, loses heat or needs more mechanical cooling than expected.

For renovation context, see Existing Home Energy Rating vs Renovation Energy Assessment.

Common mistakes in existing homes

Common glazing and shading issues include:

• large west-facing windows without effective shading
• replacing windows without reviewing orientation
• using the same glazing product on every elevation
• adding internal blinds but ignoring external summer sun
• installing shading that blocks useful winter sun
• upgrading glazing while leaving major draughts unresolved
• assuming double glazing alone will solve overheating
• ignoring nearby built form and site exposure

A good assessment can help separate the visible symptom from the underlying performance issue.

What information helps a glazing and shading review?

Before requesting a home energy rating or upgrade review, it can help to prepare simple information about the windows and shading conditions.

Useful information may include:

• photos of each side of the home
• photos of major windows and doors
• photos of eaves, awnings, pergolas or external blinds
• notes on rooms that overheat or feel cold
• known window replacement history
• glazing product information, if available
• floor plans or real estate plans showing window locations
• renovation drawings, if window changes are proposed

For a full preparation checklist, see What Information Do You Need for a Home Energy Rating?

FAQs

Why do glazing and shading matter in existing homes?

Glazing and shading matter because windows can drive heat gain, heat loss, glare and comfort problems. In existing homes, poor glazing or inadequate shading can increase heating and cooling demand.

Does a home energy rating assess glazing?

Yes. A home energy rating may consider window size, location, orientation, glazing type, frame type and related window performance information where it can be identified or assessed under the relevant pathway.

Does a home energy rating assess shading?

Yes. Shading may be considered because it affects how much direct sun reaches windows and other glazed areas. The exact shading inputs depend on the assessment pathway and available information.

What is the difference between glazing and shading?

Glazing refers to the glass and window system itself. Shading refers to elements that reduce or control direct sun on the glass, such as eaves, awnings, external blinds, verandahs or nearby built form.

Can better shading reduce overheating?

Yes. Appropriate external shading can help reduce unwanted summer sun on windows, which can reduce overheating and cooling demand. The best shading strategy depends on orientation, climate and window design.

Should glazing be upgraded before or after insulation?

Glazing and insulation should be reviewed together. The best upgrade sequence depends on the home, climate, comfort problems, budget, renovation timing and whether windows, shading or building fabric are the main performance issues.

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Building Fabric

Insulation in Existing Homes

Insulation is one of the most important building fabric elements in an existing home.

It helps slow heat transfer through ceilings, roofs, walls and floors. In practical terms, this can help a home stay warmer in winter, cooler in summer and less dependent on mechanical heating and cooling.

For existing homes, insulation is also one of the areas most likely to be uncertain. It may be missing, incomplete, compressed, damaged, hidden behind finishes or different between the original home and later renovations.

Why insulation matters in existing homes

Many existing Australian homes were built before current energy efficiency expectations were introduced. Some have little insulation. Others have insulation in one part of the home but not another. Some have had upgrades added over time without clear documentation.

This matters because insulation helps the home resist unwanted heat flow. In winter, it can help reduce heat loss. In summer, it can help slow external heat entering the building. Without adequate insulation, heating and cooling systems may need to work harder to maintain comfort.

For homeowners, insulation is often one of the first building fabric issues worth understanding before choosing appliances, solar or other energy upgrades.

How insulation affects a home energy rating

A home energy rating considers how the dwelling performs as a whole system. Insulation is one of the key building fabric inputs because it affects heating and cooling demand.

Where insulation is present and effective, the home may be better able to maintain comfort with less active heating and cooling. Where insulation is missing, incomplete or damaged, the rating may reflect higher thermal loads or poorer comfort performance.

For a broader explanation of assessment inputs, see What Does a Home Energy Rating Actually Measure?

Ceiling and roof insulation

Ceiling and roof insulation are often important because roofs can be a major pathway for heat gain and heat loss. In summer, roof spaces can become very hot. In winter, warm indoor air can be lost through poorly insulated ceilings or roof assemblies.

In existing homes, ceiling insulation may be missing, patchy, compressed, disturbed by trades or inconsistent between old and renovated areas. Roof insulation may also vary depending on the roof type, ceiling type and previous upgrades.

A rating or assessment may need to identify what is known, what is visible and what remains uncertain before insulation performance can be properly understood.

Wall insulation

Wall insulation can be harder to confirm in an existing home because it is usually hidden behind internal linings and external cladding or masonry.

Some older homes may have little or no wall insulation. Some renovations may have added insulation to new walls but left original walls unchanged. This can create uneven comfort between rooms or parts of the house.

Wall insulation is often easiest to review during renovation, when walls are already being opened or upgraded. This is why insulation should be considered early in renovation planning.

Floor insulation

Floor insulation can be relevant where the home has suspended floors, exposed subfloors, garages below living spaces or areas that feel cold underfoot in winter.

Not every home will have the same floor insulation opportunity. A concrete slab behaves differently from a suspended timber floor. Access, moisture conditions, ventilation and construction type all affect what can be assessed or upgraded.

As with other insulation types, floor insulation should be reviewed as part of the whole building fabric rather than treated as a separate product decision.

Renovations can create insulation gaps

Existing homes often contain different layers of construction. The original dwelling may have been built to one standard, while an extension or renovated area may have been built to another.

This can create insulation gaps. A rear extension may be better insulated than the original home. A converted garage may have different wall and roof performance. A renovated living area may have new glazing but no corresponding wall or ceiling upgrade.

Understanding these differences can help explain why one part of a home feels comfortable while another performs poorly.

Insulation is not the only performance issue

Insulation is important, but it does not work alone. A well-insulated home can still overheat if windows are unshaded, if glazing is poorly selected or if summer sun enters the building at the wrong times.

A home with new insulation may still feel draughty if there are air leakage issues. A home with solar panels may still need building fabric improvements if heating and cooling demand remains high.

This is why insulation should be considered alongside glazing, shading, draught sealing, ventilation and mechanical systems.

Insulation and summer overheating

Insulation can help slow heat entering the home, but it is not a complete overheating strategy on its own.

If a home has large unshaded windows, poor ventilation, dark roof surfaces or high internal heat gains, insulation alone may not prevent summer discomfort. In some cases, a home may hold heat for longer if night purging, shading and ventilation are not considered.

This is why overheating should be assessed as a whole-home performance issue, not only an insulation issue.

Insulation and draughts are different issues

Insulation slows heat transfer through building elements. Draught sealing reduces uncontrolled air movement through gaps, cracks and leakage points. Both can affect comfort, but they are not the same thing.

A home can be insulated but still draughty. It can also be relatively well sealed but poorly insulated. The best retrofit strategy often considers both thermal resistance and air leakage together.

This will be covered in more depth in the related article on draught sealing and air leakage in existing homes.

How an assessor may review insulation

In an existing home assessment, the assessor may need to determine what insulation information is available and how reliable it is.

Useful evidence may include:

• visible insulation in accessible areas
• renovation documentation
• builder or installer invoices
• product labels or specifications
• photos taken during previous works
• homeowner records
• plans or construction notes
• safe access observations

Where insulation cannot be verified, the assessment may need to treat that information carefully according to the relevant pathway. For more context, see What Does a Home Energy Rating Assessor Look For?

When should insulation be upgraded?

Insulation may be worth reviewing when a home is difficult to keep comfortable, when heating and cooling use is high, when rooms perform unevenly or when renovation work creates access to walls, ceilings, roofs or floors.

It may also be worth reviewing before replacing heating and cooling systems. If the building fabric is weak, new appliances may be forced to work harder than necessary.

The best timing depends on the property, climate, access, budget and broader upgrade pathway.

Should insulation be reviewed before solar or new systems?

Often, yes. Solar, batteries and efficient appliances can reduce energy use and emissions, but they do not automatically fix poor thermal comfort.

If a home loses or gains heat quickly, the heating and cooling demand may remain high. Reviewing insulation and other building fabric issues first can help ensure system upgrades are properly sized and better matched to the home.

A home energy rating can help identify whether insulation should be part of the upgrade sequence.

Renovation is often the best time to review insulation

Insulation upgrades can be easier and more cost-effective when they align with renovation works. If ceilings, walls, floors or roof areas are already being opened, the opportunity to improve insulation may be much stronger than after finishes are complete.

This is especially important for extensions, internal reconfigurations, roof replacements, recladding, floor works and major services upgrades.

For renovation pathway advice, see Existing Home Energy Rating vs Renovation Energy Assessment.

FAQs

Why is insulation important in existing homes?

Insulation is important in existing homes because it helps slow heat transfer through ceilings, roofs, walls and floors. This can improve comfort, reduce heating and cooling demand and support better energy performance.

Does a home energy rating assess insulation?

Yes. A home energy rating may consider insulation in ceilings, roofs, walls and floors where the information is available, visible, documented or able to be assessed under the relevant pathway.

What insulation should be checked in an existing home?

Useful areas to check include ceiling insulation, roof insulation, wall insulation, floor insulation, insulation around extensions or renovations, and areas where insulation may be missing, damaged or poorly installed.

Can insulation improve an existing home energy rating?

Insulation upgrades may improve the energy performance of an existing home, especially where insulation is missing, insufficient, damaged or poorly installed. The impact depends on the home, climate, construction and other building features.

Is ceiling insulation enough for an existing home?

Ceiling insulation is often important, but it may not be enough on its own. Walls, floors, windows, shading, draughts and heating or cooling systems can also affect comfort and energy performance.

Should insulation be reviewed before a renovation?

Yes. Renovation is often a good time to review insulation because walls, roofs, floors or ceilings may become accessible. Reviewing insulation early can help avoid missed opportunities and poorly sequenced upgrades.

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Comparison Guide

Existing Home Energy Rating vs Renovation Energy Assessment

An existing home energy rating and a renovation energy assessment can both help improve a home, but they are not the same service.

An existing home energy rating looks at the current performance of a dwelling that has already been built. A renovation energy assessment may look at proposed changes, design options, compliance requirements and upgrade sequencing for a renovation project.

The difference matters because many homeowners begin with a simple question about comfort or running costs, then realise those answers need to be translated into practical renovation decisions.

Why this comparison matters

Renovation projects often begin with a practical problem. The home is too hot, too cold, too expensive to run, difficult to ventilate or uncomfortable in certain rooms.

A home energy rating can help explain what is happening in the current dwelling. But once renovation work is being planned, the question changes. The project team may need to know how proposed works affect performance, whether the design meets approval requirements and which upgrades should be prioritised.

That is where the distinction between rating the existing home and assessing a renovation pathway becomes important.

What is an existing home energy rating?

An existing home energy rating assesses a dwelling that has already been built. It helps describe the home’s current energy performance, comfort and upgrade potential.

The assessment may look at insulation, glazing, shading, orientation, heating and cooling, hot water, solar, batteries, ventilation and comfort concerns. It is grounded in the dwelling as it currently stands.

For the broader definition, see What Is a Home Energy Rating for Existing Homes?

What is a renovation energy assessment?

A renovation energy assessment reviews energy performance in the context of proposed renovation works. It may look at how the design, construction scope, materials, glazing, insulation, shading, systems or layout changes affect the home’s performance.

Depending on the project, it may also support compliance advice, design coordination or upgrade sequencing. The assessment can help a project team understand what should be improved during the renovation rather than after the work has been completed.

In simple terms, a renovation energy assessment asks: how should the proposed renovation respond to the home’s energy performance goals and requirements?

The core difference: current performance vs proposed change

The simplest distinction is this: an existing home energy rating looks at the home as it is now. A renovation energy assessment looks at the renovation pathway and how proposed changes may affect performance.

An existing home rating asks: how does this dwelling currently perform?

A renovation energy assessment asks: how should the proposed works improve or respond to the home’s energy performance?

When might you use an existing home energy rating?

An existing home energy rating may be useful before renovation decisions are made, especially when the homeowner wants to understand current comfort, running costs and performance issues.

This may include:

• understanding why the home is hot or cold
• identifying weak points in the existing building fabric
• reviewing insulation, glazing and shading
• understanding whether heating and cooling systems are working too hard
• deciding whether upgrades should happen before or during renovation
• preparing for future sale, lease or disclosure expectations
• understanding the current dwelling before design work progresses

For more detail on what is measured, see What Does a Home Energy Rating Actually Measure?

When might you use a renovation energy assessment?

A renovation energy assessment may be useful once there is a proposed scope, concept design or set of upgrade decisions to review.

This may include:

• reviewing proposed glazing changes
• assessing insulation upgrades in the renovation scope
• checking whether shading is adequate
• reviewing heating and cooling strategy
• considering hot water and electrification options
• coordinating solar or battery decisions with renovation works
• supporting energy compliance for proposed works
• comparing upgrade scenarios before construction
• helping the design team avoid late-stage performance changes

This type of assessment is most useful before drawings, specifications and construction decisions are fully locked in.

Can a renovation project need both?

Yes. In many renovation projects, both forms of assessment can be useful at different stages.

An existing home energy rating can help establish the baseline: how the home performs before the renovation. A renovation energy assessment can then help apply that information to proposed works, design decisions, compliance questions and upgrade sequencing.

Used together, they can help avoid isolated upgrades that look useful on their own but do not fit the full performance strategy for the home.

Why assessment should happen before renovation decisions are locked in

Energy assessment is most useful when it happens early enough to influence the project. If the renovation design is already finalised, the opportunity to improve orientation, glazing, shading, insulation and system strategy may be limited.

Early review can help the project team understand whether comfort issues are caused by poor insulation, unshaded glazing, draughts, inefficient systems, layout problems or a combination of factors.

This can reduce the risk of spending money on upgrades that do not address the main performance problem.

Where compliance may fit into a renovation assessment

Some renovations are only about voluntary improvement. Others may trigger planning, building or energy compliance requirements depending on the location and project scope.

For example, a NSW alteration or addition may need BASIX if it meets the relevant threshold. Other projects may need NCC-related energy compliance support, such as DTS or another pathway.

This is why a renovation energy assessment may need to consider both performance improvement and compliance context. For NSW projects, see Existing Home Energy Rating vs BASIX.

Does a home energy rating tell you what to renovate?

A home energy rating can help identify performance issues and possible upgrade opportunities. It may show whether the building fabric, windows, insulation, systems or solar strategy should be reviewed.

However, turning a rating into a renovation scope usually requires design thinking. The right upgrade depends on the home, budget, timing, access, construction feasibility, comfort goals and whether the project has compliance requirements.

This is where a renovation energy assessment can help translate rating insights into practical project decisions.

Why upgrade sequencing matters

Renovation projects are one of the best times to improve energy performance because walls, roofs, windows, services or finishes may already be changing.

But the sequence matters. It may be better to improve insulation and draught sealing before upsizing heating and cooling systems. It may be better to review shading before replacing glazing. It may be better to coordinate solar and electrification with switchboard or hot water upgrades.

A renovation energy assessment can help connect these decisions so that upgrades work together rather than competing with each other.

How this differs from new-home NatHERS

A renovation energy assessment should also be separated from new-home NatHERS where the project context is different.

New-home NatHERS usually assesses a proposed residential design before construction. Existing home energy ratings assess a real dwelling that already exists. Renovation energy assessment sits between those worlds when a current home is being changed through proposed works.

For that distinction, see NatHERS Existing Homes vs New Home NatHERS Assessments.

Which pathway do you need?

The right pathway depends on the question you are trying to answer.

You may need an existing home energy rating if the question is:

• How does this home perform now?
• Why is the dwelling uncomfortable?
• Which current features are affecting energy use?
• What performance issues should be understood before design begins?

You may need a renovation energy assessment if the question is:

• How will proposed changes affect performance?
• Which upgrades should be included in the renovation scope?
• Does the renovation need energy compliance support?
• How should insulation, glazing, shading and systems be coordinated?

When both questions matter, both pathways may need to be considered together.

Practical implications

For homeowners, the distinction helps avoid jumping straight to product decisions before understanding the home’s performance.

For designers, a renovation energy assessment can help integrate energy performance into the design process before drawings and specifications are locked in.

For builders, it can help identify where upgrades need to be incorporated into the construction scope rather than treated as optional extras later.

For consultants, the key is to clarify whether the client needs a current-state rating, proposed-work assessment, compliance support or a combination of these.

FAQs

Is an existing home energy rating the same as a renovation energy assessment?

No. An existing home energy rating assesses the current performance of a dwelling that has already been built. A renovation energy assessment may review proposed changes, compliance needs, upgrade options or design decisions for a renovation project.

When would you need an existing home energy rating?

An existing home energy rating may be useful when you want to understand how the current home performs before making upgrade, sale, lease, electrification or renovation decisions.

When would you need a renovation energy assessment?

A renovation energy assessment may be useful when proposed works need energy performance advice, design review, compliance support or upgrade sequencing before the renovation is finalised.

Can a renovation project need both?

Yes. A renovation project may benefit from an existing home energy rating to understand the current dwelling and a renovation energy assessment to review proposed changes, compliance needs and upgrade options.

Does a home energy rating tell me what to renovate?

A home energy rating can help identify performance issues and possible upgrade opportunities, but a renovation energy assessment may be needed to apply those findings to design choices, construction scope and project documentation.

Should energy assessment happen before renovation design is finished?

Yes. Energy assessment is usually most useful before renovation decisions are locked in, so insulation, glazing, shading, heating, cooling, hot water, solar and ventilation choices can be considered early.

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