According to the Building Research Association of New Zealand (BRANZ), it is estimated that buildings are responsible for up to 20% - one fifth - of New Zealand’s greenhouse gas emissions.
Emissions from buildings are measured in two ways: firstly, through the production and transportation of materials used in their construction, and then by carbon used to heat, cool and use a building once it’s complete. Unsurprisingly, the emissions stack up pretty quickly for a standard New Zealand building.
Not so for houses built by Rangiora-based Chatterton Homes. Since 2017, Chatterton Homes has been exclusively building passive homes; extremely energy-efficient buildings in which a comfortable interior climate can be maintained without active heating and cooling systems. Passive homes use airtight construction, thermal-bridge-free detailing, heat recovery ventilation and high-performance glazing to create super-insulated homes that are comfortable, warm, dry and healthy. The result? Lower carbon emissions in both the production of materials and throughout the life of the home.
“My interest in this type of building started by chance,” explains Chatterton Homes director, Brent Chatterton, who has been a builder for over 30 years. “Way back in 2007 my neighbour was playing around with some structurally insulated panels (SIPs) in his garage and I wandered over to see what he was up to. He asked if I’d like to be involved in a house build that he was using the panels in. I agreed and went down a bit of a rabbit hole finding out about the panels and passive homes.”
This was something of a light-bulb moment for Brent, who has always had an interest in sustainability and energy-efficient homes.
“It was a steep learning curve,” he says. “Since then we’ve been on a long journey to educate our clients around what a passive home is and how it’s beneficial both environmentally and to the homeowner. Here in New Zealand people are sceptical. We have that Kiwi mentality of ‘just throw on another jersey and she’ll be right’. But people are coming on board. Since 2017, Chatterton Homes has been exclusively building passive homes, which shows the increase in demand.”
Brent can speak first-hand about the benefits of owning a passive home. Since building his own one, he’s never looked back and among the many benefits - including reduced carbon emissions, long-term cost savings, zero mould or dampness, minimal power costs and consistent comfort levels - there’s one that tops them all. “My wife, Claire, used to suffer from asthma,” says Brent. “Since we moved into our new build, she doesn’t need any medication for her asthma. If we go away and stay somewhere else, she needs her inhaler. Once we’re back, she doesn’t need it anymore. This just reaffirms that we’re creating healthier homes for people and we’re improving people’s lives. We’re proud of that.”
Brent says that clients are slowly becoming more savvy around the environmental benefits of passive homes and are asking about the carbon usage of the build and the performance of the home. “A passive house is all about numbers and formulas. We use a software package that has all the products and performance data entered into it so we can guarantee a home’s performance before we start building.”
Within the industry, Brent says things are also improving. “When it comes to carbon emissions there are two parts to a building: the embodied carbon from the creation of the building components and then the lifecycle of the home carbon used by the owners. The SIPs company we use give us the embodied carbon figures, and any engineers we engage with nowadays are all numbers focused in this area.”
Whilst there is plenty of work going on behind the scenes to improve New Zealand’s building code to reduce some of that 20% quoted by BRANZ, there’s still some way to go. Chatterton Homes, though, is well ahead of the game.
“For us it’s about creating homes that are healthier for the homeowner and for the environment.”
