For the past 10 days, Malcolm and Renee Mills haven't burned a lick of fuel to heat their 60-year-old home in Takhini.

With the bright blue daytime skies of late, temperatures have still headed south of – 20 C at night.

Not a penny has gone into heating fuel.

The sun has done it all.

The couple's decision to reduce their reliance on fossil fuels with a significant investment into solar energy will eventually pay for itself.

They didn't do it for the savings. Though it doesn't hurt that they'll recover most of their cost in a little more than eight years.

They did it because they believe in minimizing their carbon footprint.

There was also their young son's asthma condition and his sensitivity to particulate matter released by burning fossil fuels.

When the Mills purchased their duplex in Takhini five years ago, it was meant to be a starter home until they could move into the new Whistle Bend subdivision. There was talk of a district heating system for Whistle Bend using renewable geothermal heat from the ground: right up their alley.

After it was decided the proposal for geothermal was not feasible, they lost interest in Whistle Bend.

"By that point we had already settled into this house, and we got to know our neighbours,” Mills says in a recent interview sitting at his kitchen table. "And for the first time – I have moved so many times in my life – for the first time, I felt this sense of community.

"The only thing that was not going to work for us was our house.”

The Mills began researching options to replace an old oil furnace.

They settled on a new $42,000 hot water heating system, using a combination of solar energy and cleaner burning propane to heat their home and provide domestic hot water.

"We really, really looked at a healthy home, and what we could do to help our son, and what we could do to help our community, and work within our core values.”

Mills says they didn't want to just switch from oil to electricity, in part because Mills doesn't support the direction the Yukon government and Yukon Energy are going with the territory's energy future – particularly the move to liquefied natural gas.

Instead of a standard oil tank in their basement, the Mills now have a super-insulated, 450-litre hot water storage tank. In the last 10 days, the tank has been heated entirely with energy captured by 60 solar-thermal collectors on the roof – facing south. Large copper tubes filled with glycol transfer the heat from the roof to the new plumbing system which resembles something of a NASA space project.

Heat is pumped through the home through the existing duct work.

When there's not enough sunlight, the propane boiler kicks in.

Prior to the conversion last summer, the Mills were spending an average $250 a month or $3,000 a year for home heating fuel.

They've spent $600 on propane since September when the system became operational.

In addition to the new heating system, since moving into their home, the Mills spent approximately $10,000 replacing old appliances with energy-efficient models: washer, dryer, stove and fridge.

They're not the top of the line, but they're right up there, says Mills.

For the billing period from Jan. 6 to Feb. 3, the electrical bill for the family of four was $93.20, the largest amount since September.

A normal month in the past was in the neighbourhood of $130 to $140, and a big month was closer to $290.

Hot water for the home is a lot less expensive than it used to be.

Mills says by reducing the monthly electrical bill, combined with the savings in the cost of heating fuel, the family will earn back $27,000 in eight years and three months.

The remaining $15,000 is what the couple would have had to pay for a new oil furnace in any case, so Mills doesn't factor in that portion of the cost when calculating the return on their investment.

Of the $42,000 for the new system, $17,000 was for the solar equipment and installation, and $25,000 was for the high efficiency, condensing gas boiler.

During the longer days of spring and summer, says Mills, they'll have to start dumping excess heat.

Malcolm and Renee have a couple of options in mind. Perhaps a heated greenhouse, or a hot tub.

"It's one of those interesting byproducts of one of these systems,” says Mills. "You have to look at what you do if you have to much.”

Mills points out their monthly energy savings come before they've started their project to upgrade the original building envelope, the old 2 x 4 construction used back in the army days.

Once the exterior upgrades are complete, the savings will be even more dramatic, he expects.

There's no question in Mills' mind that if a new super-green home was fitted with the same type of system, heating costs would be vastly reduced, as would the CO2 emissions.

The co-founder of the anti-fracking group Yukoners Concerned about Oil and Gas Exploration and Development is critical about the non-existence of financial incentives available here to encourage energy conservation.

Other Canadian jurisdictions like Ontario offer incentives, he points out.

Mills says no matter what one might say about the United States, it's years ahead of Canada when it comes to promoting conversation among homeowners.

Had he and Renee completed their project in the U.S., they would have been entitled to a 30 per cent federal rebate, and maybe more, depending on what individual states were offering on top of the federal grant.

In Alaska, says Mills, they would have been eligible for another $10,000.

Mills says he knows attaining zero reliance on fossil fuels is not realistic in his family's everyday life.

He is, however, willing to do whatever he can to minimize the use of oil and gas products and their impact on the environment.

To go along with the next phase, upgrading the exterior envelope, will be a modest addition.

Mills says he and Renee won't add on if it means increasing their energy use. He's convinced they'll be fine. Along with the addition will be more solar panels to produce electricity, perhaps even a special vertical access wind generator.

In fact, says Mills, he expects they'll be selling electricity back to the grid before long.