Energy Assessment FAQ's

• Why do I need a Home Energy Assessment?

  A Home Energy Assessment is an important document which generates an action plan to improve and reduce energy and water consumption in your home. Our Home Energy Assessment will provide you with expert advice to meet the minimum energy standards of the National Construction Code (NCC). Additionally, our advice will save you money on your energy and water bills. This assessment is generally completed using the NatHERS rating system and therefore the document must prove that the building achieves a minimum 6 star result.

• What is an Energy Efficiency Assessment?

  An Energy Efficiency Assessment is a formal document which proves that a building's performance meets the minimum energy standards of the National Construction Code (NCC). This is generally completed using the NatHERS rating system and therefore the document must prove that the building achieves a minimum 6 star result.

• Deemed to Satisfy versus a NatHERS Star Rating

  The two main methods used are :

  1. DEEMED TO SATISFY - ELEMENTAL PROVISIONS

   

  This method is often referred to as “Deemed To Satisfy” or DTS.

  This method assesses each of individual element in your build to ensure that they satisfy the Energy Efficiency provisions in the NCC. This includes the Total R-Value (or thermal resistance value) of the roof, the walls and in some cases the floors, as well as ensuring that your glazing and ventilation comply with the provisions.

  This is a quick and simple method for assessing compliance for your build. The advantages are that the assessment is usually cheaper to obtain, and sometimes will result in less expensive building materials being required (for example, R1.5 in your walls, rather than a higher value). This method is the best method to use for alterations and additions, as in most cases only the new elements will need to be assessed and achieve compliance.

  The disadvantage with this method is that every element needs to comply with the miniumum standard, and so there is not the flexibility to consider the whole house and 'trade-off' better performing elements against lower performing elements as with the Energy Rating Method.

   

  2.  “DEEMED TO SATISFY – ENERGY RATING”

   

  This method is referred to as NatHERS Star Rating or a NatHERS Assessment.

  With the Energy Rating method, every element of the build is entered into energy-use modelling software approved by the National House Energy Rating Scheme (NatHERS). The software models the energy required to heat or cool every habitable room in the home to a comfortable temperature across every hour of every day in the year. It takes into account many other factors such as the climate, the orientation, the breezes, the building materials, the colour of the roof, and so on. The result is an area-adjusted figure of how much energy your particular design will use across a year in heating and cooling. This figure is then converted to a Star Rating out of ten. Currently, the NCC requires a 6 Star Rating in most situations, although credits are given for some additional elements such as qualifying outdoor living areas in warmer climates.

   

  The Star Rating Method is a much more accurate and informative method for predicting energy-use in heating a home. Much more flexibility is given to home builders to compensate for specific design choices. For example, in hotter climates, lighter coloured roofs are recommeded to achieve a better Energy Rating, (as they absorb less Solar Heat than a darker colour). However, if a client wanted a dark colour roof, the Energy Consultant could model this and compensate for it by increasing the insulation required in the walls or improving the quality of the glazing required, so that the house used the same amount of energy to heat and cool as if it had the lighter roof. With the Software, it is possible to easily change particular elements to see the effect they have on the Energy Rating. For clients who are wishing to achieve an Energy-efficient home with a high Energy Rating and low running costs, this is usually the best method to use.

  Wondering which method would be best suitable for your project? Ask us the question, we will be happy to assist.

• What is a 6 Star Rating?

  The National Construction Code (NCC formally known as the BCA) requires all new residential dwellings in Australia (Except NSW)* to achieve a minimum of a 6 Star Rating using the Nationwide House Energy Rating Scheme (NatHERS), approved software.

  This NatHERS software estimates the internal temperature in each room of a dwelling for each hour of the year based on assumptions about occupant behaviour, information about the structure and specification of the dwelling and standard weather data for the dwelling's location.

  The internal temperature is compared against a comfortable temperature range and occupancy pattern to estimate the annual heating and cooling loads per square metre of floor area to keep the temperature within the comfort range. The loads are adjusted and converted into a star rating between 0 and 10. A 10 star home is unlikely to need any artificial cooling or heating to maintain comfortable internal conditions, whereas a 0 star home would offer virtually no protection from the external temperature.

   

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• What are the requirements of a NatHERS certificate?

  For an accredited assessor to assess a project through the NatHERS process, they require the full plans, sections and elevations for the building as well as the building materials and glazing types that are intending to be used so that the building can be simulated accurately.

  Generally, appliances such as, air-conditioners, etc. do not need to be known by the assessor as they do not affect the star rating as NatHERS energy ratings are based on how well designed the dwelling will be. Appliances that are added to the building and are likely to be changed in the future are not taken into consideration.

   

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• What is a BASIX Certificate?

  BASIX (The Building Sustainability Index) was introduced as part of the NSW Government’s 2004 initiative to ‘encourage sustainable residential development’ and is in effect part of the Environmental Planning and Assessment Act. The BASIX certificate aims to accommodate NSW with more resilient dwellings together with reducing greenhouse gases and water consumption.

  BASIX was established to meet targets of up to 40% reductions in water consumption as well as greenhouse gas reductions by up to 25%. As a result, this delivers financial savings for the home owner.

  BASIX Assessment

  A BASIX certificate assessment is required for the development application process in NSW and considers various criteria, such as:

  • location of the building
  • orientation size of the building
  • construction type of the building
  • window size and type of the building
  • landscaping of the building
  • appliances used within the building.

  Additionally, it also considers thermal comfort levels which lessens the amount of energy used by dwellings in order to heat or cool the house to a comfortable level.

  As well as contributing to a sustainable future of urban planning, you as the homeowner will also financially benefit through reduced water and energy bills. Your BASIX certificate will confirm that your proposed project will abide by the NSW Government’s sustainability targets since obtaining a BASIX certificate means your residential building will have passed the government’s environmental targets.

  

   

  For more information on BASIX click here

• Do I need a BASIX Certificate?

  The development application stage of every new residential dwelling built in NSW of $50,000 or more require a BASIX certificate. Residential dwellings include:

  • Single dwellings
  • Dual-occupancy dwellings
  • Townhouses
  • Villas
  • Low-rise, mid-rise and high-rise multi unit developments
  • Boarding houses
  • Guest houses
  • Hostels
  • Lodging houses
  • Backpacker accommodation
  • Multi-unit developments
  • Swimming pools and/or outdoor spa with water capacity greater than or equal to 40,000 litres or 40 kilolitres.

  Additionally, alterations and add-ons to existing dwellings which cost greater than $50,000 also require a BASIX certificate.