Building a sustainable home: Why a Six Counts :


More homes are getting advertised as "energy-efficient" in the property market, but there needs to be an independent standard by which these claims can be assessed and compared.  That is what the New Zealand Green Building Council provides through their Homestar rating tool.

A home is rated on a 1-10 scale: a rating of 1 Homestar means it needs significant work, and 10 Homestar indicates international best practice. Most existing New Zealand homes only achieve a 2-3 Homestar rating. A new home built only to Building Code would achieve 3-4 Homestar.

A high Homestar rating is an independent quality-assurance mark, like Energy Star for appliances, and increases the market value and returns on the investment made for better building practices.


energy efficient home nz

The Numaguchi Eco Home - A highly Homestar rated home.


Why a Six Counts

A rating of Homestar 6 can be achieved on new and existing homes, and here is why achieving this rating is important, especially in Central Otago, our inclement region.

This score reflects that your home is drier, warmer and healthier to live in than an average house built to minimum code. Homestar 6 means the house benefits from increased insulation and airtightness, meaning it will be cheaper to heat. It also means there's good moisture control and efficient use of heating, lighting and appliances.

Next, this rating reflects wise water usage, thanks to efficient fittings and appliances and the harvesting of rain water.

In Central Otago, we don't currently pay rates towards water usage, but the need to assess "the potential reduction in water usage as a result of metering" is one of the stated reasons on the Queenstown Lakes District Council (QLDC) website for having installed 500 water meters at randomly selected homes throughout the Wakatipu in 2015.  With water quality becoming a growing concern, the council is obligated to assess how our fresh water is used, and will most likely need to impose rates in the future.

Last, this rating reflects an effort made towards sustainability. Solar energy, veggie gardens, recycling and composting count as well as managed waste for the construction site if the home was built within the last two years. This means the home is both good for you and good for the community we live in.


eco home, build me,energy efficient home

The First home in Central Otago to receive a 6 star rating


And a house you want to live in is a house others will want to live in too. The added benefit to a desirable Homestar™ rating is marketability. asserts that insulation and sun orientation outweigh other factors for almost 90 per cent of New Zealanders.

The report explains, "This shows the real-life performance of a home, rather than cosmetic features, is increasingly crucial…Kiwis who are considering selling their homes believe it's worth upgrading performance – 88% think energy-efficient features have the potential to attract a price premium."

Building to minimum code is no longer enough as homeowners increasingly demand efficiency in their homes.  Relying on a standard to assess and compare claims of energy efficiency in homes will improve expectations and building standards in our region. 

Achieving a Homestar Six or greater is good for homeowners, renters, investors and the community as a whole.


Energy efficient home

A home worthy of at least 6 stars - The Little Black Barn Home.





  • Article supplied by Annabelle Numaguchi. Annabelle is a member of Sustainable Homes Organisation, Central Otago. More info:

  • Annabelle Numaguchi.