NatHERS star rating
NatHERS Star Rating
We offer all energy compliance avenues for satisfying energy efficiency requirements for National construction Code.
If You Are Planning To Build A New Building Or Undertake A Major Extension And Alteration, Then You Will Need To Obtain An Energy Compliance Report/Certificate For Your Building Permit Application. Nationwide House Energy Rating Scheme (NatHERS) Assessments Is One Of The Common Avenues To Satisfy Minimum Energy Efficiency Requirements Of The National Construction Code (NCC).
NatHERS Energy Rating Is One Of The Three Options Available To Satisfy Energy Compliance Of Your Residential Project.
At Energy Compliance, We Provide A 6 Star Energy Rating Service.
What is energy rating or what is NatHERS rating?
Energy rating or NatHERS rating involves using a simple software to model a house in two dimensions and apply insulation values close to the minimum requirements in National Construction Code to calculate the amount of heating and cooling your house/apartment will demand to stay comfortable. The energy demand of the house is then converted into a star rating between 0 and 10 stars in a standard energy efficiency report. If your house/apartment achieves more than 6 stars, then you get energy compliance certificate and you can use it to apply for the building permit from your local council.
What do the energy rating stars mean?
Higher star means that the house requires less artificial or active heating and cooling.
0 star house means the building fabric does nothing to maintain comfort levels.
5 star house is the thermal comfort level you feel in houses built 2005 to 2011 in Victoria.
6 star house is the minimum level of compliance as per National Construction Code*.
10 star house is 100% passive house with absolutely no artificial heating and cooling.
Who requires an energy assessment?
Australia’s National Construction Code requires all new building and major extensions to satisfy the minimum energy efficiency requirements to allow minimizing greenhouse emissions from the residential sector. If you are planning to build a new building or undertake a major extension, then you will need to obtain a report demonstrating the energy efficiency compliance of your building design to get a building permit. The 6 star certificate is the most common approach for energy compliance.
What building classes do need energy rating?
NatHERS star energy rating can be used for demonstrating energy compliance for all residential dwelling such as:
• Class 1a dwelling: detached house or one of a group of attached dwellings including row house, terrace house, townhouse or villa unit.
• Class 1b dwelling: small boarding house, a hostel or the like (for 12 people)
• Class 2 buildings: an apartment building (multi-residential) containing two or more sole occupancy units. In case of a multi-residential, the whole building collectively (not each unit) must achieve a 6 star average.
Simple building works that don’t require a building permit, also don’t need to comply with energy efficiency requirements.
What are the Pros and Cons of star rating?
Energy rating compliance approach is a cost-efficient assessment method for small and medium-sized houses. It is fast to assess the building and it costs less in terms of the assessor fee.
Star rating compares the annual heating and cooling energy demand to that of a standard 200m2 house. Depending on the conditioned area of the house, if the house is bigger than or smaller than 200m2, extra stars are reduced or added. For houses bigger than 200m2, the floor area correction factor works as a penalty and it may increase construction costs. The figure below shows the major effect that area correction penalty can have on big houses.
Also, NatHERS energy rating doesn’t provide any peak and annual usage data that has a meaning in real life. Hence apart from energy compliance, you cannot use the data from star rating to assess the viability of diffident heating and cooling system or to design it.
The key to achieve a comfortable, high performing home is to design the house for your climate and benefit from natural resources to minimize active heating and cooling demand of the house. Refer to our Passive house section where we discuss how we can assist you to build a cost-effective energy-efficient passive house.
What are the alternatives to star rating?
Considering the pros and Cons of 6 star rating, it is worthwhile to consider all other options available for a residential building energy compliance. These are:
Elemental Provisions (Deemed to Satisfy method)
This is a low cost and fast compliance method. The Deemed to Satisfy (DtS) report provides a list of prescriptive insulation values and thermal performance requirements to meet the National Construction Code (NCC) minimum requirements.
DtS compliance is fast (we can do it in a single day), low cost, and simple. The disadvantage is that the solutions based on DtS are limited and may not suit your architecture and it could be expensive to construct.
This option is recommended for small and simple buildings with small glazing area and we always try it first.
Verification Using Reference Building (VURB)
This is the ultimate energy compliance avenue. It involves modelling your building and modelling a similar house based on minimum energy efficiency requirements. It eliminates all the cons of NatHERS energy rating and allows for more accurate thermal energy modelling of your house. The main advantage is that this option can allow you to save in construction costs.
This option is highly recommended for high-end houses with high glazing area.
At Energy Compliance, we always consider construction cost reduction while minimizing the total energy demand of the house.
More about energy efficiency rating
When do you need NatHERS energy rating for your residential building?
You will need an energy rating or any other option report to demonstrate NCC energy compliance before applying for building permit.
Most of the time, clients approach energy assessor after architectural drawings are finalized. However, we recommend that you consider energy efficiency from the concept
design stage so that you can maximize your energy efficiency benefits not by simply adding more insulation but by deciding on building orientation and glazing ratios for different aspects of your building. This approach is guaranteed to help you save in construction costs.
What are the steps in NatHERS energy rating?
Data collection: your assessor will need plan view, elevation views, section cuts, glazing schedule and building fabric materials to start energy rating process.
Modelling: The geometry is modelled in a plan view (two dimension) and each room is assigned as an individual zone.
Material assignment: The wall, roof, floor and glazing materials are assigned to the model.
Regimes assignment: Different rooms/zones are assigned with occupancy schedule, required comfort temperature and internal temperature and humidity gains.
Model run and star allocation: model is run and stars are generated.
At Energy Compliance, we allow for multiple iterations to maximize star rating while minimizing the construction costs. This process will be based on a collaboration between Energy Compliance, Client and the project architect.
How long does it take to finalize a NatHERS energy rating report?
For a median sized house (approximately 160m2), it will take us 2 to 3 days to finish the energy star rating report.
How much a 6 star energy certificate costs?
This depends on the nature, size and complexity of the building. Multiple types of windows, cathedral roofs, uneven floor levels, and multiple adjacent shading elements on the building, adds to the complexity of the work. Contact us, and one of our team members will usually respond in less than 1 hour.
Where can you find further information?
If you have any further questions about 6 Star or other options for energy compliance of your next project, refer to the following links or please contact Energy Compliance.
Our past projects
At Energy Compliance we have broad experience in Residential – Mixed Use and commercial projects. Here are some of our NatHERS rating projects. See our Projects webpage for more projects.
Gordon – NatHERS rating
Ashwood- NatHERS rating