FAIRBANKS — Sunlight poured into a large south-facing window and drenched the stained concrete floor, stones and flower beds in warmth. Like batteries, these features capture, store and dispense energy to the 2,300-square-foot house year round. Sun coming through the window has provided all the home’s heat since mid-February.
Outside, a dozen solar thermal panels stared at the Alaska Range and drank in the mid-morning sun. The panels and a stone masonry heater (complete with a bake oven) are the only heat sources in the home.
“You wouldn’t believe how many engineers have told me in the past year that it’s impossible,” Thorsten Chlupp said of the fossil-fuel free system. “I already know I need to build an outdoor swimming pool because I have too much heat.”
Chlupp, a general contractor and owner of Reina LLC, built the home off Old Chena Ridge Road in the fall and moved in with his wife and young daughters in January. The wood-frame house uses local lumber, recycled insulation and sustainable flooring and contains high-efficiency lighting and appliances. While elegant and comfortable, its biggest asset is its insulated thermal mass.
Chlupp designed the house to prove that solar energy, combined with tight construction and proper heat storage, can work even in Fairbanks. It’s poised to be the northernmost passive house in the world (a label for buildings that consume very little energy). He plans to produce his own energy when he adds photovoltaic panels this summer. Chlupp wants to see the design take off in the area. But first he must dispel the myth — among the public as well as building and solar experts — that the heating system won’t work in this climate, he said.
After all, Fairbanks is cut off from solar energy for all of December and January. Yet Chlupp has hoarded so much heat during the past few months that he has burned only one cord of wood. The last fire was three weeks ago.
“We create more storage, and we have the ability to bridge long periods of time when we don’t have sun,” Chlupp said. “In this house we can store eight million BTUs of energy within the tank and within the foundation.”
Eight million BTUs is enough to heat the home for two months.
Chlupp, 37, moved to Fairbanks from Germany as an outdoor and mountaineering guide in 1996. He began building homes 12 years ago and discovered the shortcomings of conventional building in a cold climate. He started incorporating green concepts from Germany, like passive solar and airtight walls, into houses here. But when he pushed for renewables, people said it wouldn’t provide enough year-round energy for this climate and latitude. So he set out to prove the systems were effective and affordable.
Trapping and storing heat
It was 70 degrees inside Chlupp’s house, and 12 solar thermal panels standing nearly upright on his roof were caching away more energy.
“We’re producing 154 degrees off the roof right now,” he said.
His energy system ties wood and solar into a single super-insulated storage tank.
Coils of pipe inside the solar panel are filled with a glycol-based fluid that heats up and circulates wherever it’s needed. On a cold winter day, it flows through loops in the floor slab that slowly emit radiant heat. But when there is no heat demand, it goes to heat water (through a heat exchanger) in the giant tank in Chlupp’s second-floor utility closet.
The 14- by 8-foot stainless steel tank is the master battery. The water can store about 4 million BTUs of energy, Chlupp said. In December, he filled it with 5,000 gallons of 40-degree water. Now the water is between 130 and 150 degrees, unlimited hot water for weeks.
“I would have never believed that we would be able to get that much,” he said. “If I have no sun for two weeks, it doesn’t matter. I have plenty of hot water.”
A smaller 40-gallon tank lives in side the big tank and is used for domestic needs. The rest of the water simply circulates between the tank and heat exchanger, either taking or sharing heat with the rest of the house when needed.
Three coils inside the masonry heater also feed heat to the water tank.
“The masonry heater combined with this tank works like magic,” he said.
The heater is made from four tons of river rocks, experts at soaking up heat, gathered in Healy. They release radiant heat when the air temperature becomes cooler than the rock temperature.
The foundation is also designed to store maximum energy. Below four inches of blue and earthen-toned concrete is 180 tons of sand in an insulated box.
Extra heat is dumped into a 400-foot underground geothermal loop outside, which is used to preheat air used for ventilation.
Minimizing heat loss
Even before Chlupp considered energy input, he designed a house that would hold onto energy.
“That’s the baseline. You have to minimize your heat loss. Everything else comes after that,” he said.
That means 22-inch airtight walls with permeable cellulose insulation — made of 85 percent recycled newspaper — and locally made triple pane windows.
The insulation goes on the outside of the building, like the “remote” wall system tested by Cold Climate Housing Research Center.
There is no vapor barrier but moisture can escape on both sides, avoiding condensation and potential mold, Chlupp said.
Ventilation provides clean air and air conditioning.
Chlupp installed a German heat-recovery ventilator, three times bigger than domestic HRVs, to bring in fresh air.
“We know that anything besides mechanical ventilation doesn’t work here,” he said.
Thermal shutters were also installed for the windows.
“It works like a champ,” Chlupp said, sliding a 6-inch-thick shutter (R-40) across the large south wall, a nightly routine.
Target audience
Chlupp would like this system to be the norm, but first he is working the kinks out (CCHRC is monitoring his house with a grant from the Alaska Housing Finance Corporation). He has installed a half-dozen masonry heaters for clients but has only built one other house with a similar heating system.
His heating ensemble cost roughly 30 percent more than a traditional boiler system. He estimates it will pay off in about 10 years, based on current oil prices (now nearly $4 per gallon).
But he expects to knock the cost down to a traditional heating system within the next couple of years — for both new construction and retrofits.
It would be automated, like any other system, easy to plumb and affordable to maintain. The tank liner, for instance would need to be replaced every 20 years while solar thermal panels last 30-40 years, he said.
Not to mention the free energy.
“What I’m after is replacing everything fossil fuel based, because if we can get rid of it completely we’re so much better off,” Chlupp said.
“Until we have actual houses out there proving it can be done, nobody believes it.”
Contact staff writer Molly Rettig at 459-7590.
words like "difficult" and "complex" come to mind. you've done a great job, and recognized that superinsulation and thermal mass storge are the keys to leveling out the extremes of our climate. the article doesn't say where you get your electricity, but if it's the grid, that's 99% fossil in these parts, unfortunately.
i do disagree with the statement “We know that anything besides mechanical ventilation doesn’t work here". do "we" really know that? (that's like using the word "impossible" to describe convection powered ventilation. a simplified example: open a downstairs and an upstairs window at 20 below and see what happens) and...always be careful what you say to reporters, ha ha!
keep up the good work.
roger evans, p.e., alaska
http://www.arosaenergy.com/
Wow. You've been around for a long time, rationalcitizen.
Anyway, good for Chlupp. This has to be regarded as a pilot program that may lead to better things.
Boo to the naysayers.
This is still an experimental innovation, from the sounds of thinks Chlupp isn't inventing anything, just taking already proven technologies, and making them work in the interior. The cost is probably more than most can afford, but in 2 years more will be able to afford it, in 5, more, and maybe 10-30 years down the road, people will be calling this the "inefficient" system and replacing it with something else.
Also, to the naysayer that says he used fossil fuels to build this. Of course he did, but did you miss the part where most of the materials came from local recycled materials and products that were made in the interior. That means only raw goods were brought in from outside and that's if they weren't available locally. Let me know when you see the electric train crossing University Ave. going to pickup supplies from a solar powered barge in Anchorage, and don't worry, the electric train recharges its batteries going to Anchorage as it slides down the side of the earth.
The only reason what this guy built might be expensive is because of its unique nature, once it becomes the norm and if will if we know what's good for us...all the materials that went into it will become fair cheaper then they are today. But until we get this juvenile tree hunger bashing mentality flushed out of the population it won't happen.
A picture of a house on a bright sunny southern facing clearing on a hill doesn't make me think that this article is anything but a commercial for a solar building company...
All houses require energy to build. This house will consume almost zero non-renewable energy post-construction. A conventional house will continue to consume energy provided by fossil fuels after construction.
Does that help you be less stupid about that house now?
By the way, I built my 1500 sq ft house for 60k, and I don't use a drop of oil to heat it. BlazeKing takes care of it! Wood? Cut it myself.
And the rest of 340k I can spend on quality German beer! Cheers!
A friend of mine installed some vacuum tube solar collectors and a heat pump system to extract heat from the ground.
I called him up and ask how it has been working. He stated, yesterday the heat pump ran about 1 hour and collected the equivalent of 1 gallon of fuel oil at $3.50 per gallon. The cost of operating the heat pump for that hour was $.75. The operating cost of the solar collector was about $.05
During the last few weeks, the sun has consistently provided more than ample heat for domestic water usage. The surplus domestic hot water heat is stored in the ground loop system so that the heat pump recovers the stored heat when in operation after sunset and cloudy days. The estimated amount of dirt storage is 240 yd.³
Currently the ground loop temperature is 34°F, it is water is warmed to 45° by the surplus solar collector heat after water in the domestic hot water tank has been heated to 120°. Over the summer, the ground loop temperature will rise to approximately 50°. A portion of the heat will come from the solar collector and the remainder will come from the Sun.
He experimented with full-time would heat this winter. The dollar and cents affect was to lower his electric bill by approximately $66 per month for the 3 cold whether 'smonths months December, January and February. during those months the temperature ranged between 0 and 30 below.
The electricity savings was about $200 spread across the 3 cold months. During those months about 4 cords of wood was consumed– the stove was reloaded 2 to 3 times per day. If the cord wood had been purchased at $200 per cord- it would have cost $800 -- which is $300 is more than the total heating season operation of the heat pump in prior years.
Obviously the heat pump system is far less expensive than purchased cord wood at $200 per cord.. In his case the firewood was collected free from his own yard at a cost of about $70 for chainsaw blades and sharpening etc.
As a matter of interest, he purchased the package of those large compacted wood fuel logs from Sam's Club. They have a burning time of 12 hours. This morning when he checked the wood stove - one fourth of the log was left.
Unfortunately their cost is more than the cost of fuel oil – considering BTU production and stove efficiency.
Groovy. I was going for ambiance, not necessarily effect.
Invictus: a proper DNM comment would propose the use of hemp oil in place of the patchouli.
Seriously, this is an interesting piece. The guy seems to have shown that solar heating is doable. Now we just have to work on affordable. I'm not a fan of subsidized or mandated alternative-energy schemes but if this guy can make it work on his own dollar, more power to him.
We had a green house complex that was heated with warm water from an indoor swimming pool that was heated by solar energy. It worked on a year 'round basis. Since our distribution tubing was such small diameter, we had to use circulation pumps at each house. The system provided bottom heat for the plants so such warm air temperatures weren't needed. It worked well, all around and, of course, we had the swimming pool! Many of the Finnish people in SW WA., use similar systems and heat all their buildings, including their garages. They started with building a HASA, that was wood fired with 4 to 6 foot logs. They start the fire in the fall and let it die out in the spring, so they can clean the ashes out. Some are now changing from wood heat to thermal/solar, to heat the same heat sink, water tank. It's far less bother and does the same job. It can be done. It's called, 'ingenuity'!
Great idea! I was going to suggest wrapping a Birkenstock around it, hanging some nasty dreadlocks off the the roof, and injecting patchouli oil in the HRV.
I think either would work.