Aktivhaus Generates More Heat and Power Than It Needs

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We love the Passivhaus, or Passive House as it is known in America, where houses are designed to be so well insulated and sited that they need no energy other than passive solar gain to keep warm. But it can be limiting; all the windows face south and they tend to be boxy and small. Architects and builders want to break out of this limitation; we have previously shown the Plusenergihus, a Passivhaus with more windows and a solar powered heating system. Now we learn from Jetson Green about the Aktivhaus, set up to not only heat and power itself but to have some left over.


From Velfac Website
It has all of the main features of a well-designed passivhaus, including a lot of insulation (almost two feet of it in the ceiling), south facing glazing with properly designed overhangs. However, unlike a Passivhaus, Solar hot water collectors and heat pump supplement the 50% of the energy captured by the passive solar system. It is, after all, built by the company that owns Velux skylights and they are not going to skimp on windows, no matter what it costs.

They note that "Daylight intake is optimized to reduce the use of electric lights, with window area 40% compared with the normal 20-25% in a typical Passivhaus.


From the english web page:

The centerpiece for the energy supply of the Solar Active House comprises an active solar collector (solar thermal and photovoltaic energy) in conjunction with a solar heater, which switches on automatically according to your heat and hot water needs.
The intelligent control technology of this combined system is self-actuating. It provides the house with enough energy for heat and hot water all year round without the need for additional heating.
A short training session is all you need to get your "in-house power plant" up and running. After that, it will operate virtually maintenance free for years.

under construction- more photos here

But there is a price to be paid for all of this technology: Half a million pounds. Project manager Rikke Lildholdt tells the Guardian that

it as "the Rolls-Royce version" and insisting that as a commercial product, it would cost no more than a regular three-bedroom detached."Hopefully we'll set a standard for what houses will look like in the future. But this is an experiment," she says. "We're not building houses, we're building an idea."

Ariel Schwartz at Fast Company writes:

Passive houses rely on effective insulation, heat exchangers, and overall energy conservation. They don't usually produce excess energy, but they also use very little. Don't be surprised if they are ultimately usurped by active houses--most of us want to do right by the environment but also keep our creature comforts.

I don't entirely agree; the nice thing about a passivhaus is that it is simple and ultimately much more affordable and maintenance-free; about the only complicated tech in the thing is the heat exchanger. Ariel's creature comforts are expensive. And both the Passivhaus and the Aktivhaus require lots of land and clear access to the sun in winter and summer; they are essentially suburban or exurban solutions. But we can dream....