A homeowner in Denmark has found a way to maintain summer warmth year-round, even in the country's windy, cold conditions. Thanks to a greenhouse built around his house.
Svend Buchardt, a chef who designs commercial kitchens, says the enclosure lets him capture enough heat to keep his home warm for three or four days without turning on the heater.
Here's what to know
Buchardt's family home combines an insulated house with a glass enclosure that shelters spaces for dining, relaxing, and growing plants from Denmark's freezing wind. In the caption for the YouTube video tour, content creator Kirsten Dirksen wrote: "The greenhouse does that job, and it doubles as a heat battery."
Even in January, he says, the greenhouse can reach roughly 30 to 32 degrees Celsius (86 to 90 degrees Fahrenheit). Large doors allow Buchardt to transfer that solar warmth into the house; closing them afterward keeps the heat indoors.
Air conditioning isn't needed for summer comfort either; airflow does the cooling.
The house isn't enclosed as a separate unit inside the greenhouse. It is actually built as one unit, with the greenhouse supporting the roof of the interior house. Leaving one side of the house outside the glass enclosure also makes room for ventilation.
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An automatic roof window provides an outlet for warm air rising through the staircase and double-height room, while lower windows admit cooler air from the north.
More background
The structure had to be custom-designed. Standard commercial greenhouse kits presented an obstacle: Their support beams would have interfered with the home's floors. A specialist company designed the enclosure instead, and Buchardt built it alongside the house using shared structural supports.
Buchardt said the structure was engineered to support a rooftop snow load of 1 meter (3.3 feet) during a once-in-a-century storm. Tempered glass was another requirement.
The sheltered dining area serves for meals with family and friends, but Buchardt also sometimes sleeps there in winter.
Although the all-electric home still has backup heating, Buchardt reports low heating expenses, though he did not provide a bill amount.
What can be done?
Managing the temperature is a simple and manual task for Buchardt. He opens and closes doors and windows himself to bring warmth in or let it out.
However, Buchardt worries that his plants may overheat while he is away. Rain triggers the automatic windows to shut, but they don't reopen once it ends, allowing heat to accumulate.
Keeping winter warmth inside and summer heat outside depends in part on insulation. Buchardt insulated the walls bordering the greenhouse as thoroughly as the home's exterior walls.
His compact bedroom needs only five to 10 minutes to cool, he says, and he ventilates it before bedtime.
Electricity generation and shade could come from the same addition if Buchardt finds solar panels that roll onto the glass. He is still exploring that possibility.
"I live in Finland, and if I'm ever going to build a house I would do something similar to this. The cold and dark winter makes you appreciate warmth and light," one commenter said.
Where can I learn more?
Buchardt's greenhouse is one way to put the sun's warmth to work at home. These stories explore a proposed solar thermal battery and homeowners' choices about solar panels, batteries, heat pumps, and cooling upgrades.
• A DIYer plans a sub-$200 solar thermal battery, but commenters question the concrete's safety.
• In Britain, solar, battery storage, and a heat pump reportedly eliminated bills for five years.
• A U.K. homeowner seeking lower bills in retirement chose solar and battery storage before a heat pump.
• A U.K. homeowner weighs DIY solar and batteries alongside a heat pump before replacing a boiler.
• A Texas homeowner says solar and HVAC upgrades cut utility bills to zero.
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