10 minute read
Homes where people thrive
Passive House homes are designed to maintain a temperature of 20 to 22 degrees Celsius, all year round. They are also designed to have consistent fresh air and never feel damp. The builds incorporate high performance windows and doors, excellent insulation, an airtight building envelope, no thermal bridges, mechanical ventilation and design stage energy modelling.
Homes wherepeople thrive
Passive House is a building standard first developed over 20 years ago in Germany. Since then, it’s been utilised around the world to make buildings more environmentally responsible.
It focuses on three core things: energy efficiency, comfort and air quality. Passive House Institute New Zealand chairperson, Murray
The Passive House standard isn’t just for residential, new build homes. It can be applied to existing homes and commercial buildings such as schools as well. Robertson, says there are a lot of key ideas from passive homes that have been moved across to other, similar standards.
“Things like air tightness and insulation have been slowly worked into the wider industry,” he says. Achieving the passive house standard requires a lot of planning and forethought when starting from scratch. “The plans for the build need to be thermal modelled,” Murray says. “Once the plans are done, they need to be reviewed by a certifier who makes sure it’s all correct.
“During the construction phase, you need to keep records to show you’re adhering to the plan. This means taking lots of photos. Finally, there’s tests once construction is complete to make sure no air is leaking.” Passive House Institute New Zealand has just produced a handbook to educate interested parties around their standard. Murray says it comes off the back of the knowledge that there are big changes happening in New Zealand’s building code. “The New Zealand government is starting to adopt passive house models in the building code. Kianga Ora even have several projects going that use the Passive House standard.”
One of the key features of creating a Passive Home in New Zealand is maintaining a constant temperature. When designers begin modelling, they take into account the climate around the home.
“New Zealand has a remarkable climate diversity. Passive House designers work with 19 different climate zones that are based on detailed NIWA data. The zones take into account factors such as average temperatures, altitude and whether the build site is inland or coastal.”
Murray says Passive House is working off integrity. “In the past there have been lots of sustainable and environmental housing produced, but they haven’t performed properly. “So there’s lots of misconceptions around what we do.” Murray says that if you follow the systems that are backed by decades of research, there’s integrity and it works.
Passive House Institute New Zealand PO Box 11766 Wellington enquires@passivehouse.nz www.passivehouse.nz
Superhomes and Passive Homes
Building better matters for people and the planet
By Jason Quinn, engineer and building scientist
If we choose to build better, New Zealanders will be happier, healthier and more comfy, all while making massive savings on their heating and cooling bills.
It’s 100 percent possible to create buildings that are a comfortable temperature all the time and are always perfectly ventilated with just the right amount of fresh, filtered air. No draughts, no damp, no mould—all with up to 90 percent savings on heating and cooling. I head a building science consultancy focused on two things: improving human comfort and wellbeing; and addressing climate change. All this, through building better. We like maths and evidence and rigorous analysis. That’s why we value the international Passive House building standard, because it delivers all the benefits for people I’ve described above. The single most important thing that goes into making a Passive House is modelling how the building will perform, early on in the design stage. To get technical, what’s needed is a ‘design-stage thermal energy model’. You see claims of “passive house principles” popping up as more people get on board with building better homes than the Building Code minimum. But a passive house is more than extra insulation and better windows.
Over the past 30 years, thousands of certified passive house buildings have been successfully built—on every continent, in every kind of climate. Certification is carried out by third party experts, independent of the project’s designer or builder. It’s the building owner’s guarantee that they’ll get the building performance and benefits they paid for.
How passive house performance contributes to mitigating climate change
There’s good work happening on designing buildings that have less embodied carbon emissions.
In brief, that means using less material like concrete and steel, because their manufacture is energy intensive and releases a lot of carbon dioxide. Embodied carbon calculations also take into account the whole life cycle of a product, including transportation and disposal. Reducing embodied carbon is important but reducing operational carbon is the first and vitally necessary step. Keeping a house warm and heating hot water account for the largest fraction of energy used in constructing and operating a building over its lifetime. Passive House levels of performance hit the sweet spot, balancing costs with benefits.
Oculus Architectural Engineering
Oculus Architectural Engineering is a group of passionate enclosure/façade engineers on a mission to provide guidance and resources to design buildings with comfort, health and performance as top priority.
Passive House design considers all of these attributes as standard, and also minimises the requirement of energy that is consumed in a standard home. A certified passive house is comfortable to live in year round, 24 hours a day, in all rooms throughout the house at an energy cost of just 15kWh/ m2 per year (about $650/year for a typical house or around $200 for a typical apartment). The surface temperatures of walls, windows, floors and ceilings are also all designed to prevent condensation and mould growth, with no draughts or wind rushing through the home, which minimises maintenance.
Designing to Passive House for apartments in Auckland can be more cost effective than complying with the Government’s Healthy Home Standards, and results in a far healthier and more economical way to operate and maintain building long-term. The New Zealand build industry needs to shift the mentality of ‘how it’s always been done’ and start designing and building better. With help from Oculus, better doesn’t need to cost more - they provide the answers and support you need when looking to build smarter.
Oculus Architectural Engineering Auckland | Wellington | Queenstown oculusltd.co.nz | 09 820 0364
oculusltd.co.nz | 09 820 0364 Auckland | Wellington| Queenstown
Passive aggressive: DCD's mission to change the way New Zealand builds
DCD Building specialises in thermally efficient, high-performance homes that provide a better quality of life for the owners and have less impact on the environment. So why aren't more construction companies following their lead?
Dennis Dowling, the founder and chief executive of DCD Building in Queenstown, has very high standards. In fact, his company won't build anything unless it's what he calls thermally efficient or high-performance.
Sense and sensibility
Just as electric vehicles are on their way to becoming the norm in some markets because they are better for the environment and, despite a larger upfront cost, are less expensive in the long run, he believes the same will happen with thermally efficient homes in New Zealand.
“When I established DCD in late 2014, the interest level was about a two out of ten. But the interest and education level among consumers is growing. Now it's at about five out of ten," Dowling says. And things are changing across the board. Some valuers are now factoring thermal efficiency into their analysis. "The kids are healthier, you sleep better, it's much quieter, you use less energy, the whole house is liveable and there are far smaller fluctuations in temperature. Those valuers that don't factor the difference in are doing a disservice to their profession because they are valuing properties the same even though the quality of life and durability is different."
Keep it tight
The Passive House movement was started in Germany about 31 years ago and Dowling says homes built to that standard are nearly five times more resolved than a codecompliant building in New Zealand. He's not a Passive House purist and there is a range of different definitions for high-performance or thermally efficient homes, but he does believe in the philosophy and builds homes with a high degree of airtightness, lots of insulation and a ventilation system that retains heat but exchanges air. Changes to building codes in some countries have meant that their buildings rise above or get so close to Passive Home levels of air tightness that it has basically become the building standard, he says. That's not the case in New Zealand, however. "Between 2014 and 2018, Vancouver went from one passive house to 2,600. New Zealand in 2018 had 24."
And our expectations of warmth are also a long way behind. The World Health Organization's recommended indoor temperature is 18C (or 21C for homes with babies or the elderly), and anything below that is deemed detrimental to the occupants' health. A study by Statistics NZ in 2018 showed that the winter temperature was under 18C in a third of New Zealand homes (and was also too hot in a third of homes during summer).
Build better
DCD focuses on building high-end residential homes and, when people are already spending millions, making it thermally efficient is a relatively small additional cost.
Dowling says the goal when he started the business was to be nationally recognised and to create homes that performed well but took traditional forms. And that goal was achieved in 2018 and again in 2021 when DCD won the Master Builders' Supreme House of the Year for the southern region.
Deep impact
Building in this way will also play an important role in reaching our carbon emission reduction targets, he says. While there have been improvements in energy efficiency over the years, inefficient buildings are still a major issue and in 2018, nearly 9.4 percent of domestic carbon emissions were building-related. "The largest chunk of a building's carbon footprint is not the construction, it's the ongoing operation and maintenance of it. And, on average, our houses operate on about 20 percent of the energy of a standard house."
Most DCD homes now also feature solar panels and storage batteries, which means they are often supporting the grid by exporting excess power.
Where possible, DCD also uses locally produced, natural materials and uses admixtures to reduce the carbon in its concrete.
"But longevity, durability and efficiency is the ultimate form of sustainability so that's our primary focus."
Right from the start
While more architects are designing high-performance buildings, 70 percent of DCD's work is design and build. Because of its focus on the end result, Dowling says DCD's approach to building is very different to the norm. He likens its model to a three-legged stool: architectural design, building performance and price all need to be in parity.
Leading the way
Dowling says DCD is basically building a curated collection of homes to show what can be achieved by using certain technologies and building techniques. He believes changing the quality and performance standards of homes would improve every new building, reduce energy usage and carbon emissions, and create much healthier homes. However, right now, houses like these are the exception, not the rule.
