- Resources
- Case Studies
- Airtightness Put to the Test in a 145-Year-Old Dunedin Home
Airtightness, as part of the EnergyTight™ retrofit solution, transformed the Feisty Goat student flat in Dunedin from cold, damp and unhealthy into a house that performs to the standard of a typical new home.
Aero Airtightness Demonstration | As featured on TVNZ
What was the problem?
Despite meeting Healthy Homes requirements, which includes insulation, heating and ventilation, the flatmates reported conditions that made the house difficult to heat. One of the flatmates, Dylan, said the 145-year-old flat was freezing and that the heat pump made little impact and was turned off.
“It’s usually colder inside than it is outside,” explains another flatmate, Toby. “We’ll just put the heat pump on for 10 minutes or as little as we can and then just layer up. Put a thermal, a hoodie and then a puffer jacket and beanie on basically to stay warm. There’s little gaps everywhere and you can basically feel the draught within 20 minutes again.”
The NZ Green Building Council’s Matthew Cutler-Welsh says: “Living in a cold, damp house has a really big impact on peoples’ health. And we see that in the statistics. We have some of the highest asthma rates in the OECD. And really high rates of respiratory illness.”
At least one of the flatmates experienced ill effects on his health. His mum Sarah told TVNZ he’s always been somewhat prone to asthma and wheeziness, but that this has become more prominent since he’s moved into the flat. “Knowing that he is at a low level of illness is not great”, she says.
What are the results?
The results for this house were impressive. Initial blower door pressure testing found the flat was at 16 ACH50 while a typical new home in New Zealand would sit between 7 and 9 ACH50. This means that under normal conditions, with no pressure applied, the flat experienced 19 complete air changes in the house per day. A heater would have had to heat this home up from scratch 19 times.
Following the EnergyTight™ upgrade including air sealing, a later test showed that the flat now performs like a newly built home in terms of airtightness. Masked, the structure measured 1.5 ACH50. The final unmasked test measured the whole home at 6.7 ACH50, at the better end of a typical new New Zealand home.
Toby says: “It’s a gamechanger basically. This has completely turned our house into a liveable warm environment. You put the heat pump on for 10 minutes and it’s warm for hours.” Another flatmate adds: “With just a bit of work that happened all in one day it’s completely transformed this flat.”
Having a home that’s easy to heat to a healthy standard is a relief for parents as well. Sarah says: “It just feels great to know that they’re so much warmer and that they’re living in a much healthier environment.”
Which airtightness upgrades were retrofitted?
The EnergyTight™ retrofit solution that was implemented in this house included AeroBarrier air sealing, window draughtproofing and the installation of mechanical ventilation.
For AeroBarrier air sealing, the house was pressurised and a sealant released. The sealant followed the flow of the escaping air and filled all the small gaps in the walls and ceiling. Draughtproofing the windows took care of any air previously escaping around the windows. And finally, a new Daikin heat pump and integrated ventilation unit was put in place to ensure a controlled flow of healthy, fresh air into the home.
Airtightness and mechanical ventilation are two of the key components that EnergyTight™ uses to make a house warmer, healthier and more energy-efficient. All EnergyTight™ homes are measured and certified.
“It’s a gamechanger basically. This has completely turned our house into a liveable warm environment. You put the heat pump on for 10 minutes and it’s warm for hours.”
How much did it cost?
Traditional ways of improving the liveability and energy-efficiency of an older home can often be too expensive and disruptive for owners to consider. Jason Marks from On Your Marks Property Services says: “It can be very invasive. Especially if you’re doing it the traditional way. You’ve got to have people up in the ceiling putting insulation in. Flashings.”
Improving airtightness with AeroBarrier air sealing typically costs $8,000–$10,000 and takes about a day, with no changes to wall linings. For many homes, that alone makes a real difference. Where windows leak badly, draughtproofing can take it further.
Chris Caiger, Director and Founder at Aero New Zealand, says: “Most homeowners would have no idea that this kind of option is available. Airtightness isn’t really commonly used in New Zealand at all. In most other countries it’s statutorily required by law. You don’t need to do anything with your wall linings. It’s simple and pretty quick to do. And it’ll be as effective as doing a huge renovation.”
How can airtightness improve your house?
Draughty homes are a common problem in New Zealand as there is no requirement to measure airtightness, unlike in many other countries. Matthew says: “About a third of NZ homes are damp. And about half of them are colder than the occupants would like.”
“In New Zealand we don’t have any requirement for airtightness or air pressure testing in any of our buildings. Even our houses,” he says. “And that is quite rare across the world. In places like the UK every single new home has to have a pressure test before it can get its final certificate.”
While the Healthy Homes standard is a good start, airtightness is the missing piece that can truly create warm and healthy living conditions. Airtightness, in combination with mechanical ventilation, is easy to retrofit and extremely affordable compared to a full renovation.
Find out more about EnergyTight™ and how it can help improve your home.
Want to achieve results like this?
