Small improvements are not enough Homestar 6 rating effectiveness questioned

18 November 2020 by Jason Quinn

Rochelle Ade’s doctoral research findings have had quite a bit of media attention in recent weeks. Not surprising, given her claim that Homestar ratings aren’t delivering what they claim (and that the rating tool may be breaching the Fair Trading Act).

Effectively, Ade measured the temperature and relative humidity of 30 homes in Auckland: those built according to the current Building Code, older buildings and new buildings that met Homestar 6 standards. Bottom line? They all sucked on the basis of the measurements used.

The indoor temperature was below 18C for Homestar 6 buildings 56% of the time; for Code minimum buildings 64%; and for older buildings 71%. (Ade calling this third category “vintage”‘ is confusing. I think it refers to uninsulated single-glazed villas.)

As you would expect, relative humidity was bad as well for all of these dwellings. (When I quoted numbers to some German building scientists studying mould in buildings their jaws literally dropped open. When capacity for speech returned, they said, ‘but everything will mould at those levels’. I replied, yes and it does. That was a bit of a conversation killer.)

Homestar Version 4 at the 6 star level was intended to be a tiny step up from the Building Code legal minimums in Auckland so the results are not surprising to me. I’d rather point out that the performance of the new buildings were closer to that of the old buildings than the Homestar 6 star buildings were to the new buildings. Sounds like the Building Code is not fit for purpose … but I’ve said that before.

Other coverage of the topic:


Radio NZ

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