7 star NatHERS rated dwellings are around the corner as the new requirement for homes in Australia. What are some considerations to keep in mind when designing your dwelling to achieve that 7 star NatHERS Certificate? Let us consider 9 different ways we can do that:
1. Involve your NatHERS assessor early!
It is a habit for us building designers to get in touch with our consultants once we have locked in our designs with the client and a DA set of plans have been produced. However, now it is more important than ever to involve your NatHERS assessor early in the design process. Us NatHERS assessors have been trained extensively to improve star ratings and to give options to achieve a 7 star rating and higher. Involving a NatHERS assessor early to give possible suggestions on the design of the dwelling will help to achieve a higher star rating at a lower cost and hassle than amending the design at the DA plan stage or using crazy high-performance glazing.
2. Orientation
Orientation affects the design of a dwelling in different ways in different places around Australia. NatHERS recognise this and that is why there are 69 different climate zones defined by NatHERS. It is important to design for shade and solar access depending on the location. A dwelling in northern Queensland may be affected greatly by larger eaves, not allowing sun direct access into the house. On the contrary, a Tasmania house may benefit from smaller to no eaves, allowing for greater solar access all year round. Somewhere more centre like Sydney or Perth may need a mix of the two, with an eave bigger enough to block out the high summer sun but not big enough to block out the heat in the winter allowing for direct solar access, keeping the house cool in summer and warm in winter. Repositioning a house plan on the lot can make a huge difference to the star rating.
3. Improving glazing
Double and triple glazing prices have gone down in the recent years possibly making them an option in the design. Having a good idea as to which window manufacturer and glazing performance you will use early on in the design will significantly help the performance of the dwelling as well as stop any scares in the construction phase when the owner sees the price tag on the window they are required to use, possibly leading to them requesting an amended NatHERS certificate. The size of the windows, its placement and the shading are important considerations early on in the design and should be designed to suit the climate. High performance glazing should be used as a last case option to get over the line, but poor thermal design and orientation may cause for higher window performance.
4. Increasing rooms
Having more doors in your dwelling may sound like it wouldn’t improve the star rating. However, this allows the NatHERS software to simulate the mechanical heating and cooling estimates more accurately. Closing off rooms like the end of hallways, bottom of the stairs or occasionally used rooms like the media or rumpus rooms may have an effect on the end result and may be just what you need to get over the line.
5. More insulation
More insulation may have an effect on your NatHERS certificates star rating depending on the climate. However, there are other places that can be insulated that usually are forgotten about. Insulating the slab edge, underneath the slab, garage wall and internal walls as well as the laundry and bathroom internal walls will make a big impact. Also, did you know that changing your design from a concrete slab on ground to a waffle pod actually has an effect on the dwelling’s performance? Waffle pods provide insulation under the slab and are usually significantly cheaper to build, a possible good option to consider.
6. Fans
Having fans specified on the plan will improve the cooling score on your NatHERS certificate. This may be something the owner is planning to do after construction, but by specifying this on the plans at the DA stage allows for your NatHERS certificate to reap the benefits also.
7. Colours
Specifying colours early will improve your rating. The colour of the roof and external walls does have an impact on your NatHERS certificates star rating. Using lighter roof and wall colours in hotter climates while darker colours in the cooler climates will have an effect on your star rating. Even specifying the window frames colour can make a surprising difference!
8. Lighting plan
NatHERS certificates require that ceiling penetrations are shown. If these penetrations aren’t shown on the plan, a worst-case scenario must be used, using more lights than what the house will probably be built with, so it is important to provide a lighting plan when possible. Fewer ceiling penetrations will always give you a higher rating. It is important to make sure that ceiling lights are used, that they are IC4 rated so that the ceiling insulation doesn’t get disrupted. Roof windows and skylights also will lower your star rating so try and leave them out when you can.
9. Flooring
Same as with the ceiling penetrations, a NatHERS certificate requires that the type of flooring be specified and if it is not specified, the worst case scenario is used. This includes tiles to wet areas and the kitchen and carpet to the rest of the house (excluding garage), giving a lower rating. If it’s possible, show what flooring is to be used in each room as this will lead to a better star rating.
As we have seen, achieving a 7-star NatHERS certificate for your home in Australia will soon become a new requirement, and there are several considerations to keep in mind during the design process. It is crucial to involve a NatHERS assessor early on, as they can provide valuable suggestions to improve the star rating at a lower cost. It is important to pay attention to orientation, improving glazing, increasing rooms, adding insulation, specifying fans, colours, and lighting, and carefully choosing your flooring. every decision matters in the pursuit of a higher star rating. By following these tips and working with a qualified NatHERS assessor, you can ensure your home meets the energy efficiency standards required for a NatHERS certificate. This is particularly important for residents of major Australian cities, such as Sydney, Melbourne, Brisbane, Perth, and Adelaide, where the demand for NatHERS certificates is high. So, start designing your home with NatHERS certificates in mind, and enjoy a more energy-efficient, comfortable, and sustainable living environment.
For more information about these tips and tricks or anything BASIX or NatHERS related, please feel free contact me directly.