Comparison Guide

Existing Home Energy Rating vs DTS

An existing home energy rating and DTS compliance belong to very different parts of the residential building process.

An existing home energy rating helps assess how an established dwelling performs now. DTS, or Deemed-to-Satisfy, is a National Construction Code compliance pathway used to show that a proposed building solution satisfies relevant requirements.

The difference matters because one pathway is about understanding real built performance, while the other is about demonstrating compliance for design or construction work.

Why this comparison matters

DTS is a common term in building compliance, while home energy rating is becoming more common in the existing homes performance space. Because both can appear in renovation or residential upgrade conversations, they are sometimes confused.

A homeowner may ask how their existing dwelling performs. A designer may ask how a proposed alteration can comply with the NCC. A builder may need to know which construction provisions apply. These are related conversations, but they are not the same question.

Clear separation helps avoid requesting the wrong service or assuming that one document can replace another.

What is an existing home energy rating?

An existing home energy rating assesses a dwelling that has already been built. It helps explain how the home performs for energy efficiency, comfort and likely upgrade potential.

The assessment may look at the real dwelling as it stands, including construction, insulation, windows, shading, heating and cooling, hot water, solar, batteries and comfort issues.

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

What is DTS?

DTS means Deemed-to-Satisfy. In the National Construction Code, DTS provisions are prescribed ways of satisfying relevant Performance Requirements.

In simple terms, a project team may follow the relevant DTS provisions where they are suitable for the project, instead of preparing a separate Performance Solution. DTS is therefore linked to compliance documentation and approval pathways.

It is not a general rating of an existing home as it currently performs.

The core difference: assessment vs compliance method

The simplest distinction is this: an existing home energy rating assesses performance. DTS demonstrates compliance through prescribed NCC provisions.

An existing home rating asks: how does this dwelling perform now, and what could improve it?

DTS asks a different question: does this proposed building solution follow the relevant Deemed-to-Satisfy provisions for compliance?

When might you use an existing home energy rating?

An existing home energy rating may be useful when the main question is about the current performance of a dwelling that has already been built.

This may include:

• understanding why a home is hot, cold or draughty
• planning energy upgrades
• reviewing insulation, windows or shading
• preparing for electrification
• deciding whether to install solar or batteries
• planning a staged retrofit
• preparing for sale or lease disclosure
• reviewing a residential property portfolio
• understanding a home before renovation decisions are made

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

When might you use DTS?

DTS may be used where a building design or construction solution can follow the prescribed NCC provisions that are deemed to satisfy the relevant requirements.

This may be relevant for:

• new residential projects
• alterations and additions
• renovation projects requiring building approval
• design documentation
• construction compliance pathways
• NCC energy efficiency compliance
• projects where a Performance Solution is not being used

DTS is therefore tied to building compliance, not simply to understanding how an established home performs today.

Can a project need both?

Yes. A renovation or alteration project can involve both a compliance pathway and a performance assessment.

For example, a project may need to demonstrate NCC compliance for proposed works using DTS or another pathway. At the same time, the owner may want an existing home energy rating to understand how the current dwelling performs before deciding which upgrades to prioritise.

In that case, DTS supports compliance for the proposed works, while the home energy rating supports better understanding of the existing dwelling.

DTS does not replace an existing home energy rating

DTS is not designed to provide a rating of an existing home as it currently performs. It is a compliance method for satisfying relevant NCC requirements through prescribed provisions.

A project may satisfy DTS requirements and still have broader questions about the comfort, efficiency or upgrade potential of the existing dwelling.

This is why DTS should not be treated as a substitute for an existing home energy rating where performance understanding is the goal.

An existing home energy rating does not replace DTS compliance

The reverse is also true. A home energy rating should not be treated as proof that proposed building work complies with DTS requirements.

If a project requires NCC compliance documentation, the correct compliance pathway still needs to be followed. This may involve DTS, a Performance Solution or another accepted pathway depending on the project.

The rating may inform decision-making, but it does not automatically become the compliance evidence for proposed works.

How does NatHERS Existing Homes fit in?

NatHERS Existing Homes is part of the wider national move toward energy ratings for established dwellings. It is different from DTS because it focuses on rating existing home performance rather than demonstrating that proposed work follows prescribed NCC provisions.

NatHERS provides energy ratings for new homes and is being expanded to include ratings for existing homes. That expansion helps create a clearer language for understanding the performance of homes that have already been built.

For the existing homes pathway, see What Is NatHERS Existing Homes?

DTS is not the same as a Performance Solution

DTS is one way to satisfy NCC requirements. A Performance Solution is another pathway that demonstrates compliance by showing how a proposed solution meets the relevant Performance Requirements.

This matters because project teams sometimes use DTS, sometimes use Performance Solutions, and sometimes use a combination of approaches. The right compliance method depends on the project and the relevant code requirements.

An existing home energy rating sits outside that comparison. It is not a DTS pathway or a Performance Solution. It is a rating or assessment of the existing dwelling’s performance.

Which pathway do you need?

The right pathway depends on the question being asked.

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

• How does this existing home perform now?
• Why is the dwelling uncomfortable?
• Which upgrades should be considered first?
• How can the home be improved before renovation, sale or lease?

You may need DTS or another compliance pathway if the question is:

• Does this proposed building work comply with the NCC?
• Can this design follow the Deemed-to-Satisfy provisions?
• Is a Performance Solution needed instead?
• What evidence is needed for approval or certification?

When the scope is unclear, the project details should be reviewed before selecting the pathway.

Practical implications

For homeowners, the distinction helps avoid asking for compliance documentation when the real need is to understand current comfort and energy performance.

For designers and builders, the distinction matters because DTS relates to the proposed work and approval pathway, while an existing home energy rating relates to the current dwelling.

For renovators, both may be relevant. The project may need compliance documentation, while the homeowner may also want to understand which upgrades should be prioritised.

For consultants, the key is to clarify whether the client is asking about NCC compliance, existing home performance, or both.

FAQs

Is an existing home energy rating the same as DTS?

No. An existing home energy rating assesses the current performance of a dwelling that has already been built. DTS, or Deemed-to-Satisfy, is a compliance pathway used under the National Construction Code to show that a proposed building solution satisfies relevant requirements.

What does DTS mean in building compliance?

DTS means Deemed-to-Satisfy. It refers to prescribed provisions or methods that, when followed, are deemed to satisfy the relevant Performance Requirements of the National Construction Code.

When would you use DTS?

DTS may be used when a project team wants to follow the prescribed National Construction Code provisions rather than preparing a Performance Solution. It is generally connected to design, approval and compliance documentation.

When would you use an existing home energy rating?

An existing home energy rating may be used to understand the current comfort, energy performance and upgrade potential of an established dwelling. It is often relevant for homeowners, renovators, sellers, landlords and property professionals.

Can a renovation need both DTS compliance and an existing home energy rating?

Yes. A renovation may need NCC compliance documentation, including DTS or another compliance pathway, while also benefiting from an existing home energy rating to understand the current performance of the dwelling before upgrade decisions are made.

Does DTS replace NatHERS Existing Homes?

No. DTS and NatHERS Existing Homes serve different purposes. DTS is an NCC compliance pathway, while NatHERS Existing Homes is an emerging rating pathway for assessing the performance of homes that already exist.

Pathway Review

Unsure whether you need a rating or compliance pathway?

Certified Energy can help clarify whether your project needs an existing home energy rating, DTS-related compliance support, or another residential assessment pathway.

Send project details for pathway review