Thursday, March 12, 2009

Photons, Part Deux

The solar panels have been working since Tuesday, and today I got to see the meter wheel spinning backwards, the sign that power is flowing back into the grid rather than from it. It's all about the Benjamins...

Output this afternoon was about 2,600 watts, less than the 3,100 rated watts, but we'll work on that.

The inverter display has a unique rap-with-your-knuckle interface that discourages (ouch!) obsessive checking, but otherwise provides useful information. 

1,000 cfm @ 50 pascals

We conducted the blower door test this afternoon. John the Building Performance Consultant set up the blower door (above), turned on the fan, and he, Barry the Builder and I went hunting for air leaks.

The result: 1,000 cubic feet per minute at 50 pascals. Recall that 2,380 cubic feet per minute (0.2 - 0.3 air changes per hour naturally) is the Energy Star requirement and that a more aggressive, but reasonable target is 1,200-1,500 cfm (0.1 - 0.15 air changes).

The blower door made it easy to find leaks that otherwise would have been missed, and Barry plugged as many as he could.

And we can do better -- there were a few areas that Barry couldn't seal right away, but which will be done before the drywallers come in. We think we can get down to 800 cfm, which is very, very good, particularly considering how much wall we have compared to the volume of the house.

Money well worth spending (I think, I haven't yet seen the bill).

Wednesday, March 11, 2009


The Hermitage as seen from the Digital Globe satellite last July. It's dead center, where the driveway extends straight West from the road. Right there, between the trees.

Tuesday, March 10, 2009


We have photon power — the solar dude from Full Spectrum Solar and the gentleman from Alliant Energy tested and commissioned the system today.

With the fog, the panels were putting out 200 watts — quite the return on investment!

The blower door test is scheduled for this Thursday afternoon. This will be a great test of construction/insulation quality.

Friday, March 06, 2009


The energy-saving philosophy nowadays is "build it tight, ventilate it right." Above is an example of the first part.

Now that most of the rough electrical and plumbing is done, and the weather is above 40 degrees (for the moment), the foam insulation can be sprayed on. The Gaco Western 2 pound high-density spray foam has an excellent R value of 7 per inch and, because it seals air leaks (unlike batt insulation), eliminates the need for a vapor barrier.

The next step is to do a "blower door test" to see how air-tight the building is. GDS Associates, our Energy Star consultant, will perform a blower door test that tries to suck the all air out of the house. If the house is well-sealed, very little air will flow through; if it's leaky, then a lot of air will come through the blower door. 

To get an Energy Star certification for the house, we need less than 2,380 cubic feet per minute (0.2 - 0.3 air changes per hour naturally) can flow through the meter at a test pressure of 50 pascals. We're going for, however, a tougher target of 1,200-1,500 cfm @50pa (0.1 - 0.15 air changes).

We're going to do this blower door test as soon as the insulation is finished, and before we put the drywall on. This is so that we can easily find any leaks (with a smoke pencil) and seal them up. If we put the drywall up first, we might have to tear some of it down to plug some leaks.

This airtightness creates a new problem, mold. So the "ventilate it right" part becomes critical in bringing in fresh air and maintaining humidity. We'll use an "energy recovery ventilator" to exchange stale indoor air for fresh, filtered outdoor air, and will minimize the loss of heat (in the winter) by sucking most of the heat from the exhaust air before it leaves the structure. 

Wednesday, March 04, 2009

Ah Ha!

Closer view of the previously discussed solar "ah ha!" wall installation. The idea is that once the landscaping is done, I won't be able to see the panels from the house. 

Now if the panels would only work...

[Update--panels now work--wires were reversed at the inverter. Now we have to convince the guy from the utility to come back and certify the installation.]

These are the panels, from Sunpower. Pretty nice looking compared to your average panel, eh?

The inverter for the solar panels that, as of today, works. As they do in all the best science fiction shows, they reversed the polarity, and it came to life.

Mechanical, etc.

Entry door, with fancy handle and even fancier keypad lock.

Radiant heating reflectors underneath the loft/office. The radiant heat tubes for the main floor are buried in gypcrete, which apparently is the better way to go -- more even heat, easier on the wood floor.

The mechanicals/utility room.

This is the NTI boiler that will heat the house. Apparently it's 5,000% efficient (OK, 93% or something like that), and silent. My old microwave was bigger and a lot noisier.

Ceiling, Part Deux

The first ceiling, which was part of our Arctic Hot Roof (or was that an Arctic Cold Roof"?) fell victim to an early snow in late 2007 (yes, it's been that long) that prevented the final galvalume roof exterior from being installed. Everything was fine until the big Spring thaw, when the beautiful Maple panels got soaked. So, we went with Plan B. 

Looks pretty good, perhaps better than Plan A.