The Study

Interesting modelling done on the financials for higher performance. Interesting that people will often be happy to spend $25k for a guest bedroom (for resale) but higher specs for energy performance is considered a hard sell. Higher performance means lower costs, a spare room does not save money. When we will value higher performance housing over another store room?

How home owners can save $6000 a year and stay cool New modelling shows that spending $25,000 on improving energy efficiency – and driving an EV – can save $300,000 over a 25-year mortgage.

Next up in our look at the impact of NCC22 on energy in WA - we turn our attention to NatHERS climate zone 33- Broome Airport

This climate zone is centred around Broome in the kimberley region - the housing data portal reports 211 dwellings certified here in the last three years, with a range of 5.5-7.5 stars

Our ten recent houses rated on average 5.64 stars in this zone under current requirements. Under NCC22 - the average rating rose to 5.8 stars (no changes to design or specifications). So an average increase of +0.16 stars

Of our ten houses, only one saw a reduction in star ratings, most designs saw no change to the rating, and two designs saw large improvements of +0.7 stars.

What does this mean?
It's likely that designs will need to achieve seven stars under NCC19 to achieve seven stars under NCC22 - but you may get lucky and see a decent boost in performance only need to achieve around 6.3 stars under current requirements.

Continuing with our look at the impact of seven stars / NCC22 - the next climate zone we will look at is 58 - Albany Airport. This climate zone covers the coastal strip around Albany, and extends inland over Manjimup and Bridgetown.

This is a climate zone I personally find quite stringent - the focus really needs to be on maximising winter solar passive gain, I find it hard to have too much shading in this climate - there is very little cooling energy needed in the simulations.

The housing data portal reports 724 dwellings in the last three years, with a wide spread of 5.0-7.5 stars, however the majority at 6.0-6.5 stars.

Our ten test houses rated on average in Albany at 5.76 stars. Updated for NCC2022 - these ten houses had an average rating of 5.61 - a small drop of 0.15 stars on average. While three of the ten houses had a small increase of +0.1 stars, most had a reduced rating of -0.2 stars, with one house dropping by -0.6 stars.

What does this mean?
Projects in climate zone 58 may need to target 7.1-7.2 stars under current requirements to achieve seven stars under NCC22. This may be problematic as I often find dwellings in this zone struggle to achieve compliance already under six star requirements! Please try to send designs to early assessment to get feedback on how things are looking as early as practical!

NCC2022 is still a long way from becoming mandatory in WA - but we have started to look at the impact of shifting to seven star minimums, and the introduction (in WA) of heating and cooling load limits.
Many are aware that when transition periods end, dwellings will need to achieve seven stars in NatHERS software, up from the current six star rating - but did you know that the "stars" under NCC19 and NCC22 will be different? There are different weather files, adjusted star bands and different rules for how assessors must model.

We have had a look at the impact of these changes. First up - focusing on the Esperance Climate zone, which covers the coastal nullabor strip in SE WA.

According to the Australian housing data portal - In the last three years, 56 dwellings have been certified here, all rating between 6.0 and 6.9 stars.

We have taken ten recent modelling projects, and put them in the Esperance Climate zone - the average rating came to 6.06 stars
We then changed the modelling to reflect NCC22 weather files, star bands and modelling rules (but no changes to designs or specifications) - and the average rating came to 6.29 stars

Of the ten houses tested, only one had the star rating reduce between NCC19 and NCC22 (and only at -0.1 stars). Typically - the houses all rated better under NCC22. Most saw an increase of +0.1 star, and one house went up by 0.6 stars

What does this mean - I would summarise these findings to suggest that under NCC22, in this climate zone - its likely a dwelling only needs to achieve around 𝟔.𝟖 𝐬𝐭𝐚𝐫𝐬 under current energy modelling methods. If your design is achieving around this level currently, it is likely that no further upgrades will be needed to achieve seven stars under NCC22