(Click here to view our primer on: Designing for 7 Stars)
Recently BERA was invited to speak on a panel regarding the anticipated inclusion of 7 Star Ratings in the upcoming NCC 2022. Here are our thoughts.
- What challenges do builders and designers face to meet a 7-star minimum star rating in Qld?
- NatHERS Assessors can get most dwellings to rate to 7 Stars in Queensland. So the big challenge will be achieving the 7 Stars in a way that doesn’t see a disproportionate increase in construction cost, or a sacrifice of design preferences. There will need to be more thought given to Energy Efficiency in the design process and so Energy Efficiency Assessors may need to be involved earlier in the process, with the thought that their feedback may need to influence some design change. With this increasing involvement of NatHERS Assessors, the cost of assessments may need to increase slightly to reflect this.
- The most common challenge will be the role of glazing, and helping clients in accepting the fact that there may need to be a trade-off between larger glazing areas with higher performing glazing, increased ventilation, increased insulation and so on.
- I think it is going to be challenging for the whole industry to adapt to, and the way building energy efficiency works, the jump from 6-7 is greater than the jump from 5-6. (This is because insulation and ventilation generally have a decreasing rate of return of effectiveness)
- Qld and NT still allow 5.0 Star or it’s equivalence with the very popular DTS Assessment, so we will need to see if that changes too. Otherwise, the DTS ‘loophole’ for easier compliance will become even more utilised.
2. Do we need a transition period to adopt changes? If so, what could that look like?
- We have recently come through a transition period for Section J (Commercial Energy Efficiency Assessments). There were significant changes that industry needed time to prepare for and for assessors to understand how to do the new assessments, as the jump in complexity was quite significant. However, this transition from 6-7 Stars is really just a change in degree. Assessors know that this is coming and are ready to model and advise. However, my experience with the Section J transition period was that in reality it was mainly a deferral period (understandably where in many instances it meant an increase in construction costs), and the scramble to understand and accommodate the new changes mostly happened when the transition period ended.
- From an Assessors point of view, we don’t need one. But we are almost certainly going to have one – so this time needs to be used by designers to ask “how would I get this house to 7 Stars if I had to?” and especially to try to educate consumers about the benefits of this increase. As an industry, we haven’t been really cutting through in communication to homeowners, but we have the opportunity to equate people’s desire for net-zero by 2050 to a 7 Star Energy Efficienct home.
3. How can we actually achieve 7 stars?
- NatHERS Software models the dwelling as accurately as possible, and then given the climate zone, site exposure and orientation of the dwelling, along with some occupancy assumptions, it will model the predicted temperature in each room of the dwelling every hour of the day, every day of the year. It will then use that information to predict when the occupants will utilise artificial heating and cooling, giving a predicted energy use from heating and cooling the dwelling. That amount is then area corrected, and a corresponding Star Rating is provided.
- As assessors, we are normally given a house design to assess, and we will advise the client on what is required in order to achieve the 6.0 Stars. Given the design, orientation and external colours are normally fixed, we will then advise on appropriate levels of insulation, ventilation, and glazing in order to achieve the 6.0 Stars. If the dwelling is struggling to reach that benchmark, a good assessor will then analyse the software outputs to suggest where gains might be made, normally with minimal change to the design eg externally shading a west facing window, increasing the insulation above the ceiling to beyond what the designer has specified, reducing the glazing size slightly, or even suggesting the changing of roof or window frame colour. However, once the dwelling is modelled, Assessors can also provide feedback to the designer on any number of elements, answering questions such as:
- If I increase that eave, what difference does it make to the Star Rating?
- If I increase the diameter or number of my ceiling fans, how much will I gain? and so on.
4. What do you think will be the challenge when dealing with clients regarding building Sustainability?
- Mainly understanding the trade-off between area of glazing and cost of overall glazing.
- Helping clients see that there are places where double glazing will be useful in warmer climates
- Helping clients who don’t want to run artificial air-conditioning understand that the NatHERS software will still assist them in obtaining a thermally comfortable dwelling
5. What does 7 Stars have to do with “Whole of Home”?
- Whole of Home Assessments are also proposed for NCC 2022. There will be two main compliance pathways, DTS and NatHERS. NatHERS is expanding from a thermal performance rating to also include information about the energy performance of common household appliances, such as heating, cooling, hot water, lighting, pool/spa pumps and on-site energy generation and storage (e.g. solar panels and batteries). NatHERS will allow for trade-offs.