Sunday, September 26, 2010

Colorado PassivHaus? almost...

This morning brings us a great New York Times article about where we are headed in green building design.  Bravo, people!

Here is a shot of Green Line Architects' recently completed Off-grid PassivHaus!  (Passive House to us Americans)  

The Living Room trusses are made of reclaimed timber and steel, and you can see a section of the 12" thick, R-60 SIP's (structural insulated panels) being installed above for the roof.  High insulation values, coupled with a very airtight "envelope" and proper ventilation make for an extremely energy-efficient home.  This one is estimated to be 94% more energy efficient than a standard home.  That's very near Net-Zero Energy!

Stay tuned for more news about this terribly exciting new home...


Turns out this house is 105% more energy-efficient than the standard home, which means that it is a Net-Zero Energy or NZE Home!!

Technically, it falls just short of being a true PassivHaus.  See notes from our energy consultant, Megan Gilman, of Active Energies, Inc. below:

Performance Characteristics

PassiveHaus Standard 1 • Airtight building shell ≤ 0.6 ACH @ 50 pascal pressure, measured by blower-door test.
This home had 0.1 natural air changes per hour and an ACH@50Pa of 2.14.  LEED and other programs have started using ACH@50Pa (LEED has three tiers of infiltration for this climate – required 5.0 ACH@50, 2 points for 3.5 ACH@50, and 3 points for 2.0 ACH@50.  These figures make sense… we were very close to LEED’s most stringent level.  
PassivHaus Standard 2     • Annual heat requirement ≤ 15 kWh/m2/year
(4.75 kBtu/sf/yr)
            Our annual heat requirement (according to HERS) is 12,000 kBtu/year, so this would be 5.96 kBtu/sf/year.  This might be a hangup, if it doesn’t meet their requirement.  However, they specifically say that it has to get this energy use in their software, which has specific weather and conditions, which could be a bit different
PassivHaus Standard 3 • Primary Energy ≤ 120 kWh/m2/year (38.1 kBtu/sf/yr)
Our total is 7,200 kBtu/year.  Yeah, I know that it’s weird that this is lower than the heating requirement, but this is because the PV production knocks down the total energy requirement.  I suppose the specific heating requirement is to ensure that you don’t just have a home with bad insulation and windows and slap a bunch of PV on.  Anyway, this total energy use would be 3.58 kBtu/sf/year.
In addition, the following are recommendations, varying with climate:
PassivHaus Recommendation 1  • Window u-value ≤ 0.8 W/m2/K  Window U-value is 0.213 in English units (Btu/hr-sf-degree F).  To convert to SI units, the conversion factor is 5.678, resulting in a value of 1.21 W/m2K.  They say this varies by climate, but I’d bet we’d be in one of the more aggressive climate zones.
PassivHaus Recommendation 2   • Ventilation system with heat recovery with ≥ 75%  
   efficiency with low electric consumption @  0.45 Wh/m3  I believe the HRV has an efficiency right around or above 75%.  My records show there is a 500 cfm unit (really two 250 cfm units) that runs 2.5 hours per day at 300 watts total, which is a total of 31.25 watts-hours per day, divided by 907.16 cubic meters is 0.034 W-h/m3.  This seems really low, but they wrote cubic meters, so that’s what makes it so low.  I don’t believe this item would be a problem.
PassivHaus Recommendation 3 • Thermal Bridge Free Construction ≤ 0.01 W/mK
I believe that with a SIPS shell, that this house is on par.

Wednesday, September 22, 2010

Villages in France

Check out the amazing masonry work on these buildings in France.  From L'

Bargème, Var

Châteauneuf, Côte-d'Or

Noyers, Yonne

Pérouges, Ain

Lavaudieu, Haute-Loire