Is it a Passive House?

We recently completed a new house that generally meets the criteria for Passive House but is not certified.  Can we call it a Passive House?

all photos by built photo

all photos by built photo

As more people gain awareness of Passive House, many projects claim to be similar to Passive House, using Passive House principals, almost Passive House, etc.  In Germany, Austria, and other European countries where PH is prevalent, it turns out that a majority of Passive House buildings are actually not certified (but have been modeled during design and blower door tested during construction).

modeling results from PHPP

modeling results from PHPP

Conceptually, Passive House buildings must be  superinsulated with high performance doors and windows, thermal bridge free, airtight, and mechanically ventilated with heat recovery,.  Technically, a Passive House must be modeled using special software (either PHPP or WUFI Passive) and meet criteria for Annual Heat Demand, Annual Cooling Demand (or heating or cooling load), Annual Primary Energy Demand (i.e. source energy), and Airtightness.  Certification generally involves a third-party review of the energy modeling, blower door testing to determine airtightness, and commissioning of the ventilation system.


Here’s some data on the 18th Ave Residence (as calculated per PHPP):

Treated Floor Area                2100 ft²

Annual Heat Demand           5.34 kBTU/ft²a

Heating Load                          2.92 BTU/ h ft²                                

Primary Energy                       29.5 kBTU/ ft² a

Site Energy                              11.1 kBTU/ ft² a

Airtightness                            .48 ach50

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main wall assembly

5/8″ gypboard

5 1/2″ wood studs w/ dens-pack cellulose

1/2″ plywood taped as air barrier

2″ rockwool exterior insulation

cedar rainscreen

R-value = 27

south wall assembly above windows

5/8″ gypboard

5 1/2″ wood studs w/ dens-pack cellulose

1/2″ plywood taped as air barrier

9 ½” TJI w/ dens-pack cellulose

½” plywood

cedar rainscreen

R value = 48

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basement wall assembly

veneer plaster

12″ Faswall blocks

1 1/2″ rockwool inserts

exterior cementitious skimcoat and waterproofing

R value = 21

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floor assembly

4″ slab on grade

10 mil vapor barrier

4″ EPS type II insulation

R value = 18

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main roof assembly

5/8” gypboard

1x4 wood furring

16” trusses w/ dens-pack cellulose

5/8” plywood taped as air barrier

4” min polyisocyanurate

½” protection board

TPO membrane roofing

R value = 78

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windows and doors

Euroclime Larch Windows and Doors w/ triple glazing

SHGC = .50

U value = 0.15 btu/hr ft² F

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Zehnder CA-350

heating / cooling

Mitsubishi Ductless Mini-Split (2 heads)

electric convection heaters for backup

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water heating

GE hybrid electric heat pump

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exterior shading

moveable wood screens

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So what do you think?  Is it a Passive House?