Energy efficiency can sometimes be a difficult concept for people to get their heads around. Yes, it can be measured, but the benefits are often intangible. So instead of focusing on the intangibles, Guy Shaw of Energy Architecture uses a simple but powerful image to convince his clients about the benefits of building an energy efficient Passive House.

"I ask people to picture themselves relaxing in their new home in shorts and a T-shirt in the middle of winter," says Shaw. "Energy efficiency is often a secondary consideration for our clients. The fact that Certified Passive Houses use less energy is an added bonus. Most of our clients just want a warm, dry, and healthy home."

So, what is a Passive House?

Put simply, a Passive House building is designed to optimise the health and wellbeing of those inside it, while consuming very little energy.

Typically, a Passive House takes a 90 to 95% less energy per year to heat than a standard house, which makes for a pretty incredible statistic. And it doesn’t have to be a house either – the principles apply to any kind of building, from schools to hospitals to community centres.

The five main principles of a Passive House design

1. High quality insulation

2. Heat control and robust windows

3. Airtight construction

4. Heat recovery ventilation

5. Thermal bridge free design

Together, these principles make sure that Passive Houses are comfortable, healthy, quiet environments to live in. It also means they have clean, filtered fresh air and zero issues with damp and mould that plague many tenants and homeowners in New Zealand.

"People who own a Passive House come home to a warm house," says Shaw.

"If it's not quite warm enough, they can turn on the heat for a while. One or two kilowatts (kW) of heat is usually enough to maintain comfortable temperatures even on the coldest days. Contrast that with the current housing stock where it can take 20 to 30 kW of heat. Building more Passive Houses would significantly reduce both our CO2 emissions and the peak load on our energy system."

Grand designs

Shaw originally trained in Wellington and spent five years working in the UK for a couple of architecture practices that specialised in energy efficient, sustainable buildings.

"The Passive House concept was just starting to take off in the UK and I was so impressed with the concept and what it stood for that I qualified as a Certified Passive House Designer," he says. "When I came home to New Zealand in 2012, the first passive home was being built here so I’ve seen the industry grow and evolve significantly over the last few years."

Energy Architecture is a specialist architecture studio that focuses on Passive Houses and energy efficient projects. Shaw is also the treasurer of the Passive House Institute New Zealand (PHINZ) whose mission is to increase awareness of the benefits and opportunities of high-performance buildings, through research, education and building industry engagement. According to their website: 'There is no longer a need to burn fossil fuels to power the spaces where we live, work and play!'

If health and wellbeing guide the decision making process, the focus shifts to the best way of delivering better buildings.

Guy Shaw, Energy Architecture

Evidence based efficiency

Every Passive House goes through a strict review, pre and post construction to make sure it complies with the standards, so clients don't just have to trust their architect or builder. It’s a proven international building standard, developed, tested, and verified over the last three decades and used around the world today. Advanced design tools and building methods make energy performance gains cost-effective and predictable.

"The beauty of the Passive House system is we can say to clients: 'This is your house design and this is what it will deliver in terms of energy efficiency,'" says Shaw. "That evidence-based model is a big selling point for the companies in the industry and the clients they work with."

Passive Houses are still a niche in New Zealand at the moment, says Shaw, but he’s hopeful that the government’s new Building for Climate Change framework will encourage everyone in this direction.

The Building for Climate Change Programme was established in 2020 to help transform the construction sector to reduce emissions and build resilience to climate change. The Programme focuses on a few different areas, including reducing the energy and water use of buildings, improving ventilation and building temperature, and reducing the total carbon footprint of buildings.

These outcomes are not so different from those achieved by the Passive House principles, which is why Shaw is optimistic.

"There's so much enthusiasm already for this type of construction and it’s not difficult to do. We have to create environments where people can thrive. What else are buildings for?

If all new buildings followed these principles and we also retrofitted our existing housing stock, the implications for the environment and the health and wellbeing of New Zealanders would be enormous."

- Guy Shaw

The Passive House movement has grown significantly in the past decade, largely in Europe, the UK, the United States, Canada, and Japan. Since the first Passive House was built in New Zealand in 2012, the movement is slowly building momentum here, and with it comes the potential to re-imagine the way we build – and the way we live.

"If health and wellbeing guide the decision making process, the focus shifts to the best way of delivering better buildings," says Shaw. "It's not about whether we should be doing it in the first place, it's about how we do it. It's about the impact it will have on people's lives."

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