It Gets Cold Here
Matthew Cutler
Podcast host. Engineer. Business Development Manger. Inspiring people to make a better place to live.
One of our main education presentations at Pro Clima involves this image showing zero degrees celsius occurring on the surface of roofing material. It's an explanation of how condensation forms when relatively warm and humid air from the inside of a building, finds its way to the cold surface of the underside of the roof. When this happens, condensation occurs. We effectively make it rain on the inside.
Leaky Buildings 2.0
At Pro Clima, we sometimes refer to this as 'Leaky Buildings 2.0' because it's a moisture problem, but the moisture is coming from the inside, not the outside. With reference to the New Zealand Building Code, this is not an E2 problem, it's an E3 problem.
Even Auckland Gets This Cold
A common misconception is that our climates in New Zealand (and Australia) are not really that cold. Surely zero degrees Celcius is a European extreme that only South Island Scarfies need to occasionally worry about?
Well, the very condition described in our presentation occurred this last weekend in May, in Auckland.
On Saturday morning I went for a run at a nearby park. Our dog was chuffed to be out and about on such a fine morning. Even my son and his friend came for a brisk walk. According to my iPhone Weather app, the air temperature was about seven degrees Celcius.
When I got to the park, this is what I found...
Night Sky Radiation
The frost was minor, and only still visible where the weak morning sun hadn't yet melted it away, but it was still frost. And there's only one way to get ice forming near sea level - it has to be zero degrees.
This is a result of night sky radiation. The air temperature remained above zero all night, but the ground radiates heat to space. Space is really really cold. When there are no clouds and the night is still, there's a relatively free path for the radiation of heat from any upwards facing surface, like the grass in a park or the roof of your house - straight out to space.
The end result is that a surface facing towards space can get colder than the air.
So our diagram is accurate and the concept is absolutely relevant across all of New Zealand and most of Australia. It gets cold here.
Solutions for Keeping Warm and Dry
Fortunately, there's a solution for designing and building in cold climates. We don't need to reinvent the wheel. We just need to recognise that our Southern Hemisphere wheels work just the same as the Northern Hemisphere ones. They may even turn in the same direction!
For more ideal roof design and Leaky Buildings 2.0, check out some of Simon Cator's great videos.
Project Manager
4 年Have to agree. Australian homes leak so much. We are all moving to improve the situation but with out the volume home builders actually taking a lead the evolution will be slow.
Senior Project Manager
4 年The coldest winter I've ever felt, after leaving Canada and arriving in Australia, was my first year living in Sydney. I lived in an old terrace house in Glebe and used to watch the frost come through the wall vents in the mornings. It was unbearable. Currently I'm living in Melbourne. You often hear Melbourne being compared to, or compete against, Vancouver as "The Most Livable City" in the World. But for some reason their climates are never compared, meanwhile they are very similar to one another. If not identical. If VIC replaced the current Planning, Rescode, Building Regulations, and the NCC, with the BC Building Code, I honestly feel the entire industry would go into shock. For once, they would be designing for climate, and the accountability would rely upon those who performed the design.
Founder & CEO of ecokit? | Certified Passive House Consultant | Leveraging technology to transform construction
4 年"We just need to recognise that our Southern Hemisphere wheels work just the same as the Northern Hemisphere ones." What an ambitious claim! I've stopped counting how many times I have been told to stop thinking as a European (advocating for Passive House and energy efficiency) and learn that the conditions are different here in Australia. There's no need for insulation, just put a hoody on :-D
Author | Creator of Write from Source? - Heal with Writing | Memoir & Writing Coach I Professional Ghostwriter I Feature Writer I Former Copywriter & Global Marcomms Strategy I What's your story?
4 年As someone born and raised in Scotland it was a huge shock to discover I was actually freezing in winter in Australia (in my home) ...lol ... needless to say my friends and family didn't quite believe it ...lol
Professor, Author and Leader in Energy Transition Engineering, MNZM, MGATE, FRSA
4 年I'm putting myself out there for a lot of piling on - but I've been used by so many people I thought I would share the knowledge and experience of "how do we" transition the legacy of spectacularly substandard to the 500YearHome. https://500yearhouse.wordpress.com/2020/05/20/background/