Designing and building homes that look after, rather than harm, the wellbeing of their occupants seems like a no brainer.
Yet data from a 2018 Stats NZ survey found that a third of Aotearoa New Zealand homes are too cold in winter, and a third are too hot in summer. It found average temperatures as low as 16°C. The World Health Organization (WHO) recommends maintaining a minimum indoor temperature of 18–20°C to maintain comfort, health and wellbeing.
If the occupants of these homes can’t afford to heat their home in winter and cool it in summer, they have no choice but to live in an unhealthy environment. It’s a serious problem, particularly for the very young and elderly.
Unhealthy homes seen as normal
Some in the building and construction industry think it shouldn’t be that way. Architectural designer Bob Burnett is founder of the Superhome Movement, a non-profit industry group aiming to transform Aotearoa’s building industry so all new homes are healthier and more energy efficient.
‘Most people associate the problem with older homes. But many brand-new builds have these same issues,’ he says.
Nor is it a problem with just basic houses. Burnett says he sees large, luxurious, award-winning homes created by respected architects with poor thermal performance and indoor environmental quality, which generate massive power bills for their owners.
‘New Zealanders just think it’s normal to have a cold, damp home with condensation on the windows in winter. They don’t realise you don’t have to live like that.’
So, why has this situation arisen?
Good design is fundamental
The trouble begins, according to Burnett, when designers prioritise aesthetics over the performance of the building and the criteria that make it a healthy home.
‘Unfortunately, design is often marginalised or, in some cases, completely absent from New Zealand’s home-building industry. Homeowners miss out because there’s limited understanding of what good design is and what it can do for them,’ he says.
The fact that many homeowners and occupants have little idea how their home works or how to keep its internal environment healthy just adds to the problem.
Take indoor ventilation for example. International guidelines on indoor air quality recommend that ventilation rates should ideally be 0.35–0.5 air changes per hour. This provides sufficient ventilation to effectively remove contaminants but is not so high as to compromise energy efficiency.
However, BRANZ research indicates that building airtightness tends to be based on the age, size and overall complexity of the building. Older homes built prior to 1960 typically had natural ventilation rates of around 0.9 air changes per hour. More modern homes built after 2000, where construction is more airtight, experience only 0.2 air changes per hour on average.
The Building Code expects occupants of more airtight homes to open windows each day to create the necessary ventilation.
‘Unfortunately, many people won’t open their windows in winter, particularly if they have to pay to heat their home. They don’t see the point when all the warmth they’ve just paid for would escape,’ says Burnett.
Building Code is problematic
The Building Code is at the root of the problem, Burnett believes. He says the building industry uses it as the primary performance target despite it falling well below the minimum standards required in other countries with similar climates.
Burnett says the Building Code does a disservice to homeowners, who are led to believe a to-Code build offers them the best possible home when this is simply not the case.
‘We have new homes being built today that meet the requirements of our Building Code but fail to meet basic WHO health standards.’
Finding better ways
Efforts like the Superhome Movement, supported by research insights from BRANZ and others try to set higher performance targets. They’re beginning to find traction with designers, builders and other building professionals as well as homeowners and occupants looking for a higher-performing home.
Burnett, a former Homestar assessor, says the primary goal of Superhome is to create awareness for homeowners and occupants about healthy homes and awareness for building professionals to help them find better ways of doing things.
To help achieve its goals, the movement created the Superhome certification, a building credential that assesses a dwelling against 10 key principles that encompass the Superhome ideal: good design, wholehome ventilation, thermal performance, energy efficiency, a very well-insulated envelope, water efficiency, high-performance recessed windows, low-carbon materials, airtightness and good waste management.
Good design solves many problems
‘The Superhome certification, and building healthy homes in general, isn’t just about sustainability or thermal efficiency – the industry has other ratings and certifications for those things. It’s about how good design can influence the quality of the internal environment and how that environment can improve the physical and mental wellbeing of building occupants,’ explains Burnett.
More than just pure building science, he describes good design as the right mix of science, materials, aesthetics and occupant-focused thinking, but when you step into a well-designed healthy home, he says the difference becomes obvious.
Navigating budget concerns
Critics of beyond-Code builds might point to the additional insulation, higher-performing windows and ventilation systems required and say it adds unnecessary costs to an already expensive process.
Superhomes do cost more, on average, although higher-performing materials and energy-efficient systems often pay for themselves in the long term. There are also the long-term health benefits for occupants to consider, with associated healthcare savings for individuals and the country as a whole.
What’s more, Burnett says good design can often provide ways around budget concerns.
‘Orient the build properly on the site, use the right amount of glazing, place the right rooms in the right locations and prioritise what’s important to the homeowner. That’s good design. It doesn’t cost a cent more,’ he says.
‘People say you must choose between affordability and performance or between affordability and a healthy home. I say there is no need. With good design, you can have both.’
On Saturday 20 July 2024, the Superhome Movement will hold its annual Superhome Tour, giving designers, builders, prospective homeowners and renovators the opportunity to visit some of the country’s highest performing and most energy-efficient homes. See www.superhome.co.nz/tours-superhome-movement for details.