As winter sets in, and temperatures plummet, it can sometimes feel as cold inside as it does outside. The reason for this is the poor thermal performance of houses in New Zealand and nowhere is that more keenly felt than in our neck of the woods. Shannon Thomson reports.

Cold, damp and draughty homes are a staple in the New Zealand housing landscape.

With open-plan layouts and large windows to enable flow of fresh air and cross›ventilation, New Zealand homes are designed to embrace warm, sunny weather.

What about winter?

The same features impact the energy performance of houses during the cold season.

A 2019 study conducted by Motu Economic and Public Policy Research fellow Dr Lynn Riggs, based at the University of Otago, linked New Zealand’s poor housing to more than $145 million in health costs a year.

Those costs were solely attributable to homes that were cold, damp, mouldy or dangerous to live in.

Central Otago holds the records for the coldest temperatures making the problem more acute here.

However, increasingly builders and industry professionals are moving towards making houses more sustainable and efficient.

One such construction company, CBG Quality Construction, based in Wanaka, is doing just that.

High-performance living . . . A home built at Galloway is leading the way in terms of energy efficiency and airtightness. PHOTO: SHANNON THOMSON

Case in point is one of its latest builds at Galloway near Alexandra.

Owner Clint Gollop said he was a certified passive house tradesman with a focus on building better and higher-performing homes for his clients.

‘‘Better built homes equates to less strain on our health system, healthier living . . . they’re healthier, quieter, warmer, drier, and just happier homes to live in.’’

The Galloway home, which is nestled on a more than 300ha property, is an example of that.

The more than 300sq m home is cut back into the hill to minimise visual impact.

‘‘We didn’t want to have too much effect on the wider environment and you can see by the nice gentle rolling hills around there’s no real sharp peaks, so we went with a nice monopitch roof so it sits in to the land nicely,’’ Mr Gollop said.

‘‘There’s a lot of rocks and stuff around Galloway so we decided we’d have some schist on there, some timber so we have a bit of rustic charm coming into the home.’’

The home was designed to sit well on the land.

‘‘Obviously the environment up here is a wee bit harder, we’re slightly higher so we didn’t want to build a home that was going to leave the client sort of charging into higher power bills and having to really try and manage that so the high› performance home does its job and so far at the start of winter. . .they still haven’t turned any heating on yet.’’

Efficient . . . Wanaka builder Clint Gollop built the high› performance home in Galloway. The number of high performance and passive homes built in the region has increased in the past 10 years. PHOTO: SHANNON THOMSON

Key to the home’s performance — and high-performance/passive homes in general — is the airtightness of the build.

‘‘The airtightness is a key sort of part of a high›performance home because if you can imagine, you could have a really well›insulated home but if you leave all your doors and windows open the cold air’s going to come in.

‘‘That would be a really bad air›leaky home,’’ Mr Gollop said.

Seechange New Zealand sustainable construction consultant Nigel Murray blower door tested the Galloway house and found it to be almost 40 times more airtight than the average New Zealand new build.

The move towards such a build was gaining traction in Central Otago, Mr Murray said.

‘‘It’s been here for quite a while, people know that this thing’s [high›performance builds] happening and high-performance and passive build numbers are growing.’’

An airtight home reduced condensation and therefore mould, reduced the energy it took to heat or cool the house and reduced the contaminants that came from outside the building.

‘‘People are healthier in the building, people are less stressed, mentally and physically happier.

‘‘There’s a lot of research that asthma is pretty prevalent in New Zealand because our housing is cold and damp.’’

He said the Galloway house delivered one of the best results he had tested in Central Otago.