Is a 6 Homestar rating all it’s cracked up to be?

What is Homestar?

Homestar is an independent national rating tool that assesses’ and measures the quality of a home’s design and build. This is measured through the overall health, warmth, and efficiency of the house. A Homestar assessor will rate your home from a 6-10 if it meets the Homestar standards laid out by the New Zealand Green Building Council (NZGBC). 

A Homestar assessor can give a rate for the initial design of the home and the completed home or after it is built. Ultimately the final rating of the completed house is the one that matters. This final assessment assures that the features in the design plans have been fully and correctly implemented.

If a house were to receive a 6 (or higher) Homestar rating it means that that house will be easier and more cost-efficient to heat and maintain at a healthy standard. A Homestar house is typically more environmentally friendly than other homes that simply meet the building code standards at the minimum requirements, and nothing more. No bells and whistles there. The NZGBC claims that if your home receives a 10 Homestar rating you have built a world-leading home.

HOWEVER

Recently a series of 6 Homestar builds has been implemented to social housing in an effort to build a more sustainable, healthy future for New Zealanders.

But recent studies from the University of Auckland are challenging the accuracy of this Homestar rating tool. And have suggested that these performance claims of a 6 Homestar house could be breaching the Fair Trading Act.

Doctoral graduate Rochelle Ade and Dr. Michael Rehm from the University of Auckland tested some of the beneficial claims of Homestar in a series of 30 Homes with a 6 Homestar rating. This collection of Social Housing was a variety of both newer and older builds and all meet the standards of the building code. This is what they unearthed:

•  All of the dwellings spent the majority of winter colder than 18 degrees Celsius. 

• Many of the homes spent the majority of the summer months above 24 degrees Celsius. 

In essence, these homes were falling short of the World Health Organisation’s (WHO) minimum healthy temperature in winter and chronically over-heating and exceeding WHO’s maximum healthy temperature in summer. Too cold in winter, too hot in summer. So, not really what people think they are getting when the NZGBC claims to be giving the residents of New Zealand healthier, more energy-efficient homes.

Some members of the design industry are starting to call Homestar out. Stating that Homestar is a checklist that can be stacked to receive a higher rating simply by implementing the most basic design aspects for a sustainable household. Rather than addressing the more pressing concerns, New Zealanders face in their housing, such as ventilation and temperature maintenance.

The members of our community living in social housing deserve more than a dwelling that is just marginally better than the minimum standards of the legal building code. Homestar is now on its fourth version and Andrew Eagles, CEO of NZGBC, says that they are open to feedback from the sector as they re-develop and improve the Homestar rating system to create the fifth version.