As cold inside as it is out: Freezing Dunedin flat gets an airtight makeover

Flatmates in the Feisty Goat flat in Dunedin's Castle St used to wear their coats inside because the house was so cold in winter.

When Aucklander Dylan Hawkesby and his four flatmates moved into the historic Feisty Goat flat on Dunedin’s Castle St in February this year, the temperature inside was pretty comfortable.

But come the winter months it was a different story. The 145-year-old villa was damp and freezing, especially at night, despite meeting the Healthy Homes Standard. Hawkesby says it was as cold inside as it was outside, and sometimes colder because the house received little sun.

“You just wear kind of what you wear outside because if it’s 5 degrees outside, it’s 5 degrees inside.”

The Feisty Goat student flat in Dunedin's Castle St, owned by landlord Tim Calder of Prime Campus.

The five University of Otago students would huddle inside wearing layers of clothing, hoodies, puffer jackets and beanies to keep warm. The single heat pump made little difference because most of the warmth leaked out as fast as it was produced, and they stopped using it.

“It was kind of a waste of power. Like you’d put it on and the house would be warm for 10 minutes and then it’d be back to normal,” Hawkesby says.

At times it got so cold he would spend nights at his girlfriend’s flat.

That was until last month when Aero Solutions picked the chilly Feisty Goat, next door to 660 Castle St where the band Six60 was born, as a showpiece to demonstrate the effectiveness of its air sealing system. Owner and landlord Tim Calder, of Prime Campus, came on board, agreeing to the work at a reduced price after consulting with his tenants.

The five flatmates, all former Auckland Grammar School pupils, moved out on a Wednesday morning and were able to move back in the following afternoon.

A removal company took away their furniture and other belongings, leaving the house an empty shell. Carpet and other fixtures were covered in plastic and holes in the house were sealed.

Chris Caiger, Aero Solutions’ founder and director, says technicians use a temporary blower door to blow air into the house, pressurising it before an atomised sealant is blown into the gaps and cracks, sealing them shut. The sealant dries like a rubbery-textured paint so that if the house moves, the substance will not crack.

Chris Caiger, founder and director of Aero Solutions.

Caiger, who has the New Zealand and Australian agency for the product AeroBarrier, mistakenly called the Feisty Goat the Leaky Goat during the Heraldinterview and he’s not far wrong. The house was so damp that most of the flatmates used dehumidifiers in their rooms.

“You’d put a dehumidifier on for an hour or two and it would fill up,” Hawkesby says.

Before the air sealing was done, the air tightness of the villa was estimated to be 20%. Now it’s around 85% airtight. Instead of around 19 air changes a day, taking the heat out with it, the Feisty Goat now has two to three air changes a day.

All up, around $20,000 worth of work was done, which included the air sealing, making doors and windows weathertight and airtight, and installing a mechanical ventilation system in the ceiling. Calder has also installed a new heat pump. And the difference?

“It’s way warmer,” Hawkesby says, “I reckon it’s worked really well.”

Ex-Auckland Grammar School flatmates outside the Feisty Goat in Dunedin's Castle St: Harry Sixton (left), Bruno Duder, Tom Jones, Toby Fox and Dylan Hawkesby.

Although temperatures have plummeted and snow fell in Dunedin earlier this week, the flatmates have noticed a marked difference in the internal temperature when they come home.

“Now if we put it [the heat pump] on it’s good for like quite a few hours,” Hawkesby says.

Caiger says the cracks and gaps in an average house add up to having a window open all the time, but the cracks and gaps in the Feisty Goat added up to a window and door being constantly open.

Overseas, air sealing technology is mainly used in new houses to meet airtightness requirements, he says. New Zealand and Australia are among the few countries that don’t require airtightness to be part of compliance.

For the past seven years, the Feisty Goat has been a “legacy” flat for Grammar boys and another group has signed up to move in next year. With a bit of luck, they’ll be able to take off their puffer jackets and beanies once they’re inside.

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