Saturday, September 11, 2010

Blower Door Test

Yesterday Building Diagnostics performed the blower door test.
This test measures the air leakage of the house.  At 50 pascals the leakage was 658 cubic feet per minute.  That sounds like a lot, but it's really pretty good.  The total house volume, including basement and attic, is about 23,000 cubic feet, which translates into about 1.7 air changes per hour (ACH).  According to the "blower door test" link above, less than 5 ACH is tight, 5 to 10 ACH is moderate and more than that is leaky.
I wanted to see how much the heat recovery ventilator (HRV) added to this number.  The HRV has two 6" diameter ducts, one intake and one exhaust, going through the outside wall.  I took a piece of newspaper and put it up to the intake.  The air going in the HRV intake hood held the paper in place.  The CFM reading went down by about 10 percent just from this.  I would guess that, if the opening was sealed, there would be about 15 to 20 percent less infiltration.  However, the purpose of the HRV is to allow ventilation.  About 75 percent of the energy which would otherwise be lost can be recovered when it passes through the HRV.

When I took the photo above, I had the camera angled down, which skewed the perspective.  I decided to fix that, which is pretty easy with photo editing software.
The mat inset into the tile and the bench both factor into the final LEED rating.  It is recommended that dirt and contaminants be contained rather than tracked into the house.  The purpose of the walk-off mat is obvious.  The bench is a spot to sit down and remove your shoes.

Building Diagnostics will take the infiltration information, along with other information regarding insulation levels, HVAC equipment efficiencies and other factors including the capacity of the photovoltaic solar system and will use this to calculate a Home Energy Rating System (HERS) score.  This score indicates how much energy this house uses compared to a code minimum house.  Then that number will be translated into a point score that will factor into the final LEED score.

Monday, September 6, 2010

Labor Day plus one year

One year ago we had a foundation.  If we knew how much work this would be, we might not have done it.  We've spent many weekends working on the house and often quietly wished for bad weather so we wouldn't mind the fact that we were inside working.  The weather this summer has been, generally, quite nice.  Then came Earl.
Earl veered out to sea further than expected and the wind wasn't so great, but about 4" of rain fell overnight.  Our basement is only about 14' above sea level, but flooding isn't an issue.  There was a very large puddle down the hill and a bit of wash-out, but otherwise it was pretty benign for a hurricane.  It did really effect businesses, though.  Labor day is kind of the last hurrah on Cape Cod, and many people left early or came late because of the potential threat.


Most people don't give much thought to window screens, but we never do things the easy way.  We have simulated divided lights (SDL's) and I hate to see them obscured by screens.  This is what I would like things to look like.
Some of the windows don't have screens, like this one which is over an opening in the Living Room and out of reach.  However, this is what the front of the house currently looks like with screens.
Most of the windows and this side of the house have half-screens.  This way the top of the window is unobstructed and the depth and shadow lines of the SDL's show through.
The view from inside is a bit better without upper screens too, although the half-screens disable the upper sash, so the double-hung windows are more like single-hung windows.  The top-down/bottom-up shades allow us privacy from the street and a view at the same time.  I like how even the little screens for the awning windows have the same lawyerly warning label.
This is a TruScene screen, which is about 50 percent more transparent than a traditional screen.  They are quite a bit more expensive, though, so we used them judiciously. 

The half-screens do require an adapter and stick out further than the upper sash.  I was worried about how they would look because of this, but it's not too bad.
We have full screens on the side and rear of the house.
You can see how they obscure the SDL's.  Also, the full screens are white and the half-screens are Cinnamon Toast color.  I was concerned that the white divider bar at the center of the screens would look out of place, but the screens do obscure this somewhat.

We really love the casement window in the Kitchen.
The sashes look like the double-hung windows but open WIDE.
The window goes all the way down to counter height and really lets the outside in.  The window opening was mis-framed and is off by about an inch from where it should have been.

I installed the tile over a month ago, but have not yet grouted it.  It looks great and will look even better when it's finished.  There are many little jobs like this left, though.