A keen DIY expert and qualified engineer made a solar panel to heat his freezing Kaikohe home using just Coke cans.
About six years ago, Terry Johnson built the panel after connecting the empty cans to plywood and a sheet of polycarbonate.
He painted the cans black to absorb as much of the sun's heat and placed the panel on the east side of the house.
"[It's] absolutely not Kiwi ingenuity. It's an invention done by people overseas that we did our own adaption of."
The family home was built in 1932. Mr Johnson tried to sell it, and decided to renovate in the process.
"It's always been a cold house," he says.
The air from the house enters into a round opening in the back of the bottom manifold warming up inside the cans.
It then re-enters the house through the round opening in the back of the top manifold - making the home about 4 deg C warmer.
Commonly known as 'beer horses', they produce about 750 watts or 1 horse power, he said.
Costing around $500 to make, Mr Johnson thought it would cost only $1.50 to run per year.
He had since left the house but believed it was still there.
And he had a few tips for people wanting a cheap alternative to insulate their house if they are willing to DIY themselves.
"I think a lot of people in Auckland should think seriously about doing this."
Mr Johnson backs secondary double-glazing; he says people could get a sheet of plastic and use magnets to connect it over the window from the inside of the house to cut down the moisture.
"Get rid of the moisture and get rid of the cold."
Another tip: placing bubble wrap over the window from the inside of rooms you don't use. You may not be able to see out of it, but that didn't really matter if the room wasn't being used, Mr Johnson said.
Another handy trick was buying a cheaper thermal camera app on your cellphone as opposed to paying thousands of dollars for a proper thermal camera.
He said these cameras can pick up where heat is leaking from inside your house so instead of trying to fix your whole house you can target the problem areas.
Build It Solar is a great website for those wanting to use their creative flare to find some of their own DIY solar build projects to save money, he said.