Sunday, December 20, 2009

Certification and testing

Certifying a Passive House is not a one-way process.  The Passive House Institute US works with builders to make sure their plans are on track to meet Passive House requirements.  One step in that process is review of our Passive House Planning Package energy modeling - the software calculation of how much energy the house will use.

We recently heard back from PHIUS, and aside from a few minor corrections they said that things were very well done.  This means we are on track to achieve Passive House Certification, pending final testing and submission of supporting construction documentation.

To further ensure that we will pass all the final tests, we performed a diagnostic air tightness check before the foam and insulation were installed.  Andrew Morphis with Green Hammer Construction out of Portland volunteered their blower door services to identify and locate any remaining points of air leakage in the exterior envelope while the primary air barrier (exterior sheathing) was still exposed.  The blower door was ultimately cranked up to a 100 Pascal pressure differential while the interior was heated with a temporary heat source, and we toured the house with a infrared gun to spot areas where cold air was seeping in.  There was very little to find aside from a door that had two corners where the weatherstripping was creased.

The standard we are tying to meet here is no more than 0.6 air changes per hour at a 50 Pascal pressure differential (0.6 ACH 50).  This means that only 60% of the entire volume of air in the house will be exchanged with outside air over the course of an hour.  If this seems like a lot of air movement, consider that the house is depressurized, which greatly accelerates the transfer.  A typical new house is easily ten times leakier.  We tried to generate an actual ACH 50 number, but Andrew did not have a small enough ring to get an accurate result.  The leakage was so low that a smaller ring will have to be implemented for the final blower door test.  We are confident that at least 0.6 ACH 50 will be met in the final test based on our initial testing.

Many thanks to Andrew Morphis and Green Hammer Construction for donating their time and expertise, and to builder Blake Bilyeu for helping me (hopefully) get the details straight!


Last week we (by "we" I mean people who are not us and actually know what they are doing) started putting up foam on the outside of the house. 

Besides insulating the house, the foam keeps moist interior air from condensing in the exterior walls in the winter.

Gutters also went up.

I like that the gutters are actually attractive.

After the foam was up, the house was wrapped and wood strips (one-by-fours) were put up that create a rain screen.

The rain screen provides a little space for water to drain away and dry if it happens to get past the siding.  Long-term durability is nice.

Meanwhile, some sweet plumbing was going in.

This is in the mechanical room.  There are three manifolds that send hot, cold, and lukewarm water through the house.  The lukewarm water is simply cold water that has been heated with the Power Pipe™!  The Power Pipe™ takes warm water from the upstairs shower and sink drains and transfers the heat to the cold water coming into the house.  This lukewarm water goes to the hot water heater and the cold spouts on sinks and showers.  Pretty cool.  The manifolds themselves make it easier to distribute water quickly to different parts of the house, so there is less waiting for the hot water to get hot.

Next up is the insulation inside the walls.  On Friday, crews came in and placed a fiber mesh on the interior of the walls.  They then blew in borate cellulose insulation into all of the cavities (dense packed to 4 pounds per cubic foot).

The bales of cellulose get dumped into a hopper in a truck outside.  The hopper breaks up the bales and sends the insulation through a tube into the house.

This guy pierces the mesh and fills the walls with insulation.  Keep in mind that the studs do not extend through the thickness of the walls, so the cellulose can easily go around corners and fill all the nooks and crannies.

It gets a bit dusty in there.

Blake wouldn't let me have his face mask.

But he was nice enough to take this shot of the attic.  They have only filled about a third of it, but you can see how thick it is in the back.  They also will fill the space between the joists under the house in the crawlspace.  They'll be back to finish these up once they order more materials.

In case you were wondering, cellulose is simply recycled newspaper treated to be suitable in walls.

If you look closely you can spot newsprint here and there.  I'm still working on reconstructing the rest of this article.  So far I've been able to determine that something may or may not have happened to one or more people.  Stay tuned for details.

The cellulose also provides sound-proofing, so they insulated the mechanical room to isolate any noise.

Once the dust settled, the house had a very different feel to it.

Walking in, the first thing you notice is that the room sounds different.  The insulation deadens any reverberation, though that will probably change somewhat once the drywall goes on.

All the wiring is hidden away.

This is the front door frame and shows about half a cross-section of the wall.  The insulation goes all the way back.

Upstairs, the space between the ceiling and the attic floor gets filled.  We were using that space for wiring since it's inside the sealed shell.

And finally we see one of the upstairs bedrooms.

The insulation in this house is a big part of what makes it special, and seeing it go in was pretty neat.  The house feels transformed.  Pretty soon drywall will go on and all of this cool stuff we be hidden away.  Good thing we have lots of photos!

Sunday, December 6, 2009

Windows are here

There was a lot of action at the house this week. The plumber and the electricians both did more installation, and the roofer is almost finished. The concrete was poured in our garage. But the most exciting thing to me was that our windows finally arrived!

The windows are special in multiple ways. Windows are an area in the home that are often not well insulated, so we bought extremely well-insulated windows to prevent heat loss. The windows are triple-paned -- we originally planned on four panes, but those did not allow in enough light to get the proper amount of solar gain we needed, so we had to drop back to three.

The U-Value on the windows -- which measures how well a product prevents heat from escaping -- is extremely low (lower is better). This photo gives some of the values for one of the living room windows:

Also, the windows are casement style, meaning they open like doors, rather than up and down. This creates a tighter seal when they are closed and locked. Most of the downstairs windows are fixed and don't open at all, which is even better for preventing air leakage. Stuart opened one of the upstairs bedroom windows:

On the aesthetics side, we chose windows with a rectangular grille on the top part, which is a Craftsman-style look that is common in our neighborhood. We decided to have dark brown grilles that match the roof color:


You can't see the new garage floor because it's covered in paper, but here is Stuart trying out the newly poured steps from the mud room into the garage:

Evidence that the plumber was here:

The frames are up for the pocket doors, which are the kind that slide in and out of the wall. We'll have three pocket doors: one on the master bedroom closet, one on a smaller bedroom closet and one in the secondary upstairs bathroom to divide the toilet and shower area from the sink area: