Tag Archives: passive house

LED lighting vs. windows

Treehugger asks if LED lighting is more efficient than daylight. It seems like a dumb question at first because isn’t daylight free? But the problem inside buildings is that windows allow heat to come and go in addition to light, and LEDs have gotten so efficient that it is not an easy question to answer whether bricking up a window and replacing the light with LEDs would be more or less energy efficient. They conclude that windows should be designed with human comfort and happiness in mind.

what’s new with “passive house”?

Well, by combining an “airtight envelope” with solar arrays, a passive house certified nursing home in Spain can actually generate more energy than it uses.

The new nursing home extension is topped with an 18 kW photovoltaic array along with 20 solar thermal panels and rooftop seating. When combined with the building’s airtight envelope, which was engineered to follow passive solar strategies, the renewable energy systems are capable of producing surplus energy, which is diverted to the old building. The Passivhaus-certified extension also includes triple glazed openings, radiant floors, rainwater harvesting and mechanical ventilation equipped with heat recovery. 

Inhabitat

So the technology exists to build like this, so why don’t we do it everywhere? Well, part of it is ignorance and resistance to adapting ideas from elsewhere to one’s own locale. A lot of it is legitimate concerns about cost. But new materials and skills can be expensive because they are in short supply locally. So, bring in a technology like this, set up local factories and training programs to build capacity, encourage entrepreneurs, provide successful examples and incentives and possibly regulations, and you can bring cost down. When the people doing it forget the old way of doing things, assume the new way is the way it has always been and the only way it can be, and are resistant to the next new idea that comes along, you have made progress.

passive house

This article describes how an old home was retrofit into an extraordinarily energy efficient “passive house“.

I’m guessing the owners are not poverty-stricken. Then again, there must be some payback period and I wonder if it is measured in years or decades. If it pays back reasonably, there should be some kind of financial arrangement that would allow ordinary people to do this.

passive house

Here is a long article with some details on the passive house standard, which promises order of magnitude energy use reductions in buildings. It was invented in the United States, forgotten/ignored in the United States, adopted in Europe, and now is finally filtering back from Europe into the United States.

The passive house standard requires a tightly sealed and heavily insulated building envelope to ensure optimum energy efficiency. The minimum airtightness level allowed is 0.6 air changes per hour under 50 pascals of pressure. To ensure that a house is in compliance with this limit and that there are no leaks, the building’s designers conduct an on-site blower door test. “The biggest challenge is the sealing,” says Priputen, adding, “If you have a weak spot you have to make all of the other areas stronger in terms of insulation and air sealing.”

The other main pillar of passive house construction is a compact air and heat exchange system that conserves energy by transferring heat and/or moisture between incoming and outgoing streams of air. Designers specify one of two systems, depending on the site’s climate: heat recovery ventilators (HRVs), which transfer only heat, or energy recovery ventilators (ERVs), which transfer both heat and moisture.