What would it cost to heat a house so that it was warm in every room 24 hours a day, no matter the temperature outside? How about $41 a year total, and that's just for hot water?
There are no room heating costs at all in a little house on a hillside in Golden Bay.
The Government has tested it and found it to be the most energy-efficient in the country, and it is very simple to build.
Lawrence McIntyre used to be a chicken farmer, and proudly so - he learnt a thing or two from poultry.
"Twenty-five years ago I learnt that insulating the chicken house kept them happier and healthier, and that sort of got me thinking," he says.
It got him thinking about the way we heat homes, then let that energy slip through our fingers. Many years later he built the most energy-efficient house in the country.
The house has been given the highest rating ever awarded by the Energy Efficiency and Conservation Authority - a nine out of 10.
The total bill for heating the home is likely to be around $40 a year.
Sick of fixing up old houses, Mr McIntyre moved the family to Germany to study Bauhaus design.
"The systems were good in Germany, but I realised there was no way the whole New Zealand building industry was going to change to the style they do it in Germany."
So he worked with a traditional Kiwi builder to adapt what he had learnt.
"These walls have three layers of Batts running at different angles which tie in through to the floor, and then they go through into the ceiling and that way there's no timber exposed, so there's no heat loss," says Mr McIntyre. "Like one big furry box."
The building itself is very simple - the focus is on clever insulation and energy saving details.
"So normally ... the windows would be on the outside, but by recessing them in they're actually sitting in the insulation of the building and it reduces condensation"
One of the best things about this house is how low maintenance it is, easy to clean and it never needs to be painted.
"To me it's more about using the resources that we have on our planet to the most effective use," he says. "So stainless steel, coloursteel, lack of painting, lack of the energy that goes into that, that's being eco."
No energy is lost through the ground either - the whole house sits on polystyrene.
"The polystyrene comes out of the ground and actually comes right underneath and sits on the window, and so you see the infrared photos, you'll see that there's actually no heat loss through that point there."
Victoria University building science students are using the house as a test case, a possible blue-print for the future.
"This is an intriguing building in the sense that it's doing things that we've been talking about for years, but it's actually doing it in practise," says Michael Donn, Victoria University School of Architecture.
What it is doing is keeping the interior warm, whatever the weather, without any heating - just a passive solar design.
"The heat from the roof is transferred down through this box behind the adobe wall, and the adobe wall takes around six hours for the heat to transfer so during the day when the roof is warm the heat's coming behind the wall, and then you're getting it later at night," says Mr McIntyre.
Sensors have been installed, which will show how well the house is performing long term. But in the short term "this is a warm comfortable place as you'd expect," says Mr Donn. "So the preliminary data is our personal experience and that experience is very positive."
This little green house does simple things well, and that grounded philosophy applies to every room.
The toilet is also the compost, but more than just a compost - the toilet is how the whole house breathes.
"With a house that's so airtight and insulated you have to have a system of breathing, and so the compost toilet is actually what makes the house breathe," says Mr McIntyre. "So it's continually sucking air through the house, heating up the compost material, which makes it very efficient and then expelling itself."
So no wasted water, compost material for the garden and believe it or not, no smell.
The house cost around $3000sqm to build - not low-cost, but not luxurious either.
"Anyone that's thinking of building a house around the $3000 figure, they could build this one straight away," says Mr McIntyre. "Anyone who's struggling with those kinds of finances could build it in phases - they could start with the insulated box and then retrofit different levels into it."
But if you would rather just stay the night, you can rent the house as a holiday home - just don't bother to bring your winter pyjamas.
If you'd like to learn more about the 'Little Greenie' ecohouse go to www.goldenbayhideaway.co.nz.