Friday, 27 March 2015

0.34 ACH @ 50Pa - We passed the first test!

Ross Elliott and Stephen Magneron from
Homesol Building Solutions collecting the numbers
from our initial blower door test.
It's was a pretty exciting day here at Turtle Falls yesterday. After months of building in record cold temperatures we finally reached the stage where we could put the house and its airtight barrier through its first blower door test. I have to admit I was a bit nervous. Tests have always jarred my nerves and probably always will.

But as the title of this post reveals, there was no need to be nervous. The guys from Crane Building Service have done an outstanding job so far building their first passive house, which was amazingly designed by Chris Straka at Vert Design Inc, modeled to achieve passive house standard by Homesol Building Solutions and the airtight installation of superior quality passive house certified windows and doors by Herrmann's Timber-Frame Homes. Ras and I extend our greatest gratitude to all the guys for their continuing support and careful attention to all the details required to get us on the right path to passive house certification.

One of the most important features of a passive house is it must be airtight to within 0.6 air changes per hour under a pressure of 50 pascal (0.60 ACH@50Pa), meaning that it will take one hour for 60% of the volume of air in the whole house to be exchanged or about an hour and 40 minutes for one complete air change. Little ol' Casa Tortuga and its band of brilliant builders achieved a mid-term test score of 0.34 ACH@50...pretty good indeed.

The meticulous men from Crane's Building Service
(l-r) Lee Ostrom, Mark Raison and Al Paige.
0.34 ACH@50Pa...well below the 0.6 required. 

To put that number in perspective, as tightly sealed as Casa Tortuga is it would take about three hours for one complete air change and this means that in the dead of winter with all the ventilation and heating systems switched off, a passive house would typically lose about 0.5°C per day, stabilizing somewhere between 10°C to 15°C (50°F to 59°F). And that's if the sun isn't shining.

Now I'll compare that to the house I grew up in...(sorry mom). Mom has been a real sweetheart to allow us to live with her during this crazy cold winter while construction continued. As much as we love Priscilla, winter is just too much for her thin-tinned walls to handle so mom graciously took us in. I must tell you that my childhood home is easily 100 years old and has had some updates over the years including a new kitchen addition, windows and furnace. I don't ever remember there being any insulation top-ups though. One cold night I noticed that the furnace was running almost constantly so my inner geek thought it might be fun to time this furnace cycling. It ran for 20 minutes, stopped for 3 minutes, ran for 20 minutes, stopped for 3...all night long and all day long for as long as those nasty -27°C days (and some -32°C) lasted. This house was losing about 1°C every 20 minutes with the heating/ventilation systems on. Compare that to the anticipated (systems off) passive house heat loss of 0.5°C per day. It makes the grief we have gone through with construction and weather delays worth every moment when I look at everything from this perspective.

So let me go back and show you some of the reasons we achieved such a good number.

The excellent triple-glazed Gaulhofer passive house windows installed by
perfectionists Adrian & Andreas of Herrmann's Timber-Frame Homes.
 These guys had smiles on their faces all week while installing in nasty
cold temperatures, even when they had to apply sealing tapes with
ungloved hands. I think they must be part polar bear! Fun guys.
Look at all the beautiful sunshine. But you know what sunshine in January
means in Eastern Ontario, eh? Minus 27°C (-17°F) or worse!  Ah, but days
like this make for some cozy temperatures inside a passive house.
The completed airtight envelope. This one inch of foil-faced insulation board
 is really all the wall/ceiling we have at the moment. The 6" (15cm) of Roxul
on the inside and 16" (40cm) of dense pack cellulose outside is still not
installed but we were reaching temperatures as high as 24°C (75°F) and
 maintaining at least 13°C (55°F) even in the -27°C (-17°F) weather,
using just one electric construction heater.
28" (71cm) of cellulose has been blown into the attic space
 by Green Giant Design Build. When settled, it should sit
 at a depth of about 25" (63cm). The R-value of the
insulation above the ceiling is closing in on 90.
The 2x6 space below the airtight foil barrier is the service chase for electrical
wires and ventilation ducts. All lights/ducts can be installed in the ceiling
 now without compromising the airtight envelope.

That's all for this post. Next up will be a smallish rambling about the heat and ventilation system for Casa Tortuga. I've lost count of how many times we've had to endure the comment that a house should not be so tightly sealed..."houses need to breathe, ya know!"

More later,

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