Posts Tagged ‘passive house’

I went on another tour of a couple of passive houses under construction in the San Jose area. The two were very different from each other.  The first is a remodel, designed by Thamby Kumaran with energy modelling by the owner-builder, Scott Heeschen.  It uses a lot of salvaged redwood for the rainscreen siding, a mixture of Marvin Integrity and Serious windows, and rainwater catchment.  Clearly architecture was a priority, since attics and flat ceilings make it easier to maximize insulation. (Compared to this beautiful vaulted ceiling)

Thamby Kumaran and passive house tourists

I am curious how the long strip of south-facing clerestory windows will perform in summer with such a minimal overhang.

Nabih Tahan and several other visitors on the back deck

Casement, awning, and fixed windows were chosen for their air tight seals.

Marvin Integrity casement windows

Several large water cisterns in the side yard

The other house I had already visited in the fall of 2010.

Cottle Zero Energy House

This one is more of a standard high-end spec house, but it seems to be quite technically competent on many levels.

Presentation to eager passive house enthusiasts.  Note the open web joists above. These make for easy routing of ducts and plumbing

“Ladder blocking” allows for more complete insulation of the exterior envelope

Insulated concrete form on display

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In the fall of 2009 I visited this Passive House on the south side of  Chicago, Illinois.  I didn’t really know much about Passive houses at the time, but I was impressed by one thing in particular.  The homeowner opened a window on the first floor and there was no rush of cold air. In fact there was no perceptible air movement at all. This was because The house is very “tight” The air didn’t rush in because there wasn’t anywhere for it to go.  I won’t go rambling on about what a passive house is here. Follow the link to my article on the topic, or just Google “passive house” or passivhaus.”

More information about this particular house:

Green Building Advisor

Interview with one of the owners

I need some more information about how it has been performing since commissioning. Perhaps the owner will make a comment on this post.

Beyond its Passive house status, the house has many fine recycled details such as these vent covers made from 100 year old soffit:

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Passive house is a fairly new word.  This recent evolutionary step in building technology comes from Austria, but many of the concepts are ancient.   The basic idea is to insulate really well and eliminate random air leakage and thereby require way less heating energy. Ideally all the heat needed will be generated by occupants, their computers and light bulbs,  and the sun.

Pretty simple, right? The devil is in the details.  Real Passive Houses also must pass a performance test to prove they actually work.

Nabih Tahan was an innovator on the west coast. The New York Times published an article about Passive Houses a houses in 2008 that mentions his Berkeley California renovation project.

Unfortunately,  Nabih’s house failed the blower door test for leakiness, so doesn’t actually qualify as a passive house, but he has measured his energy use over the last two years and it performs extremely well. He had to install electric baseboard heaters to satisfy the building code.  He rarely turns on these heaters, but since electric heat is inefficient, (a lot is wasted in transmission) his “source energy load” is slightly over the Passive House requirement.  He thinks that he would have qualified if  he had used gas heaters.

Here is a picture of Nabih’s Air to air heat exchanger (energy recovery ventilator) from Ultimate Air:

The guy in the picture designed and installed the system. His name is is George Nesbitt, and he has a company called Environmental Design-Build.

Nabih installed redwood rainscreen siding. I think it was made out of the old siding, milled into flat slats. His window details are pretty nice:

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This past Sunday I went on a tour of some cutting edge energy-efficient houses. (They are hoping to meet the Passive House Standard) These photos are of one house  in San Jose (1820 Cottle Avenue) by One Sky Homes. It is  a conventional, 3200 SF luxury tract home, but will need much less energy to operate.  According to the Passive House calculations it will be Net Zero Energy (Solar panels on the roof will provide all the required energy)

So far the house is only partially framed, but we were able to see the advanced framing techniques coming together, including this insulated header:

The house sits a top an insulated crawlspace.  This is the first insulated crawlspace I have seen myself.   The point of an insulated crawlspace is that all the ducts and water lines can run through conditioned space and energy is not lost.  The insulated crawlspace also eliminates some of the thermal bridging that usually occurs where house meets the foundation and the earth. Finally, the conditioned crawlspace stays clean and dry, which makes it far more pleasant when maintenance requires someone to crawl around under the house.    Here is a photo looking into the crawlspace from a ventilation hole:

There is, of course, a french drain all the way around the perimeter and also a floor drain in the slab to make sure  it stays nice and dry down there.

The walls are insulated concrete forms, and there is 3″ of insulation under the concrete slab as well.

Here is a photo of some of the graphics explaining the heating, cooling and ventilating system:

and another showing the anticipated energy breakdown for lighting, appliances, thermal comfort, electric car charging, and entertainment:

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