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Passivhaus & Climate Responsive Design :: AIA Seattle 2030

A quick intro to Passivhaus, and two case studies.

Rob Harrison AIA

on 23 May 2012

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Transcript of Passivhaus & Climate Responsive Design :: AIA Seattle 2030

also known as Passive House
OK. What IS Passivhaus?
A Passive House is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. Energy losses are minimized. Any remaining heat demand is provided by an extremely small source. Avoidance of heat gain through shading and window orientation also helps to limit any cooling load, which is similarly minimized. An energy recovery ventilator provides a constant, balanced fresh air supply. The result is an impressive system that not only saves up to 90% of space heating costs, but also provides terrific indoor air quality and superior comfort.
Only Three Requirements
Space heating or cooling demand must be less than 4.75 kBtu/square foot/year.

Primary energy demand must be less than 38 kBtu/square foot/year.

Less than 0.6 air changes per hour when measured at 50 Pascal with a blower door test.

How is it done?
low surface to volume ratio
additional insulation
high performance windows
no thermal bridges
careful attention to air sealing
heat recovery ventilation
optimized with PHPP software
Passivhaus is NOT...
Passivhaus is not "passive solar."
Passivhaus is not "net zero energy."
Passivhaus is not just houses.
Passivhaus is not a comprehensive set of green strategies.
Passivhaus is not "net zero energy."
Passivhaus is not "passive solar."
Passivhaus is not a comprehensive set of green strategies.
Passivhaus is not just houses.
LEED Platinum
A Few Links
That's measured according to the German TUV method (DIN-277), which measures to the inside of the walls, doesn't count the area of interior walls, storage areas or stairs above a certain height. For many buildings this means a net area ~20% less than the gross square footage. Therefore Passivhaus heating demand measured against GSF actually ends up ~20% less than 4.75 kBTU/SF/year.
Primary energy (aka "source" energy") includes heating, cooling, appliances, plug loads—everything. In Passivhaus, an energy factor is applied to account for losses in generation and transmission.
Just to give you an idea: An old house might test at >7.0 ACH@50, a typical new house more like 5.0 ACH@50, and an energy-efficient house built with attention to air sealing in the 2.0 ACH@50 range. Getting to 0.6 ACH@50 requires careful detailing by the designer and rigorous follow-through by the builder.
With such a tight building proper ventilation is a must. Code-required ventilation rates for standard houses assume a much leakier envelope, and require a lower amount of ventilation than Passivhaus does. They assume that extra "fresh" air is coming in through the cracks...like through the floor from the crawlspace...down through the insulation in the attic...around the edges of the windows....(Ick!)

Of course, in a Passivhaus you can open the windows too. It's not THAT German.
CO2 emissions
business as usual --> fully engaged
Our response to climate change will involve three aspects:
We decide now what proportion of each we (and subsequent generations) will experience.
eg: reduction of carbon emissions through:
energy conservation (Passivhaus, Living Building Challenge)
distributed clean energy production (solar, wind, geothermal)
urban density (reducing transportation energy)
eg: responding to climate disruption by:
relocation of affected populations
seawalls, dikes, flood control
food crop changes
development of vaccines
eg: affects of unmitigated climate disruption:
climate refugees
storms, flooding
economic impacts of all of the above
Rob Harrison AIA
The gross square footage of the building is 52,000 SF.
The current energy use index (EUI) is 16.
The treated floor area (based on the German DIN 277-2 method) is 39,050 SF.
The limit in Passivhaus for Primary Energy is 38 kBTU/SF/yr.

In Passivhaus, an "energy factor" is applied to various forms of energy to account for generation and transmission losses. For electricity, this factor is 2.7.

Solving for an EUI that would meet Passivhaus:

38 kBTU/SF/yr ÷ 2.7 = 14.07 kBTU/SF/yr. (gives us an annual Primary Energy usage target, taking the electrical energy factor into account.)

39,050 SF (TFA) x 14.07 = 549,434 kBTU/SF/yr (gives us the site annual energy usage using TFA for a building that met Passivhaus)

549,434 kBTU/SF/yr ÷ 52,000 (GSF) = 10.57 (gives us the EUI target for a building that met Passivhaus.)

The building as designed has an EUI of 16. A building that met Passivhaus would have an EUI of 10.5, and would use 66% of the energy of the Cascadia Center as currently designed.

Or, looking at it the other way:

52,000 GSF x 16 (current EUI) = 832,000 kBTU/yr (total annual Primary Energy usage)

Solve for kBTU/SF/yr using TFA.

832,000 kBTU/yr ÷ 39,050 SF (TFA) = 21.3 kBTU/SF/yr

Multiply that by 2.7 (the energy factor for electricity) to get the primary energy usage.

21.3 kBTU/SF/yr x 2.7 = 57.52 kBTU/SF/yr

Passivhaus requires an annual primary energy usage (source energy) of 38 kBTU/SF/yr.

The building as designed exceeds the Passivhaus standard for Primary Energy by a bit over 50%.
Passive House Consultants
nine-day intensive training
certified by PHIUS
How are they qualified?
What do PH consultants do?
run PHPP
optimize assemblies
develop envelope details
recommend products & materials
~1,500 certified Passive House Consultants in the world.
~200 in the US.
~22 in WA State.
A Different Paradigm
Conventional Approach
(in a temperate area)
Conventional Approach
(in a cold area)
(in a temperate area)
(in a cold area)
With Passivhaus on the other hand, the "furnace" stays the same (4.75 kBTU/SF/year), and the building envelope varies.
With the conventional approach, the building envelope (insulation & windows) stays (more or less) the same and the size of the "furnace" varies to suit the heat loss.
What will your choice be?
Living Building Challenge
Like "passive solar," Passivhaus does gather and use the warmth of the sun to contribute to heating the building, and it does take into account shading to keep a building cool in summer, but in a Passivhaus you won't find Trombe walls, water walls (or much talk about thermal mass, really), or earth-berming or big expanses of south-facing glass to the exclusion of windows on other sides of the building.
Passivhaus is probably the best way to get to net zero energy, because as you'll see, Passivhaus achieves a greater reduction in energy use than any other current approach--and that's *before* adding any active energy-generating systems.
We'll come back to this building later if we have time, to compare its performance with Passivhaus.
Before you continue, take a moment to click on "More" to the right of the forward arrow, and click on Full Screen. You can move forward and backward through the Prezi with the left and right arrows on your keyboard, and zoom in and out with the up and down arrows. OK!
What will your choice be?
What will your choice be?
passive survivability
energy intelligence
fresh air!
Madison Park Passivhaus
Owner/Builder: Sloan Ritchie, CascadeBuilt
Architects: NK Architects
Passive House Consultants: HARRISON architects
THERM analysis: Bronwyn Barry
Bonaparte Passivhaus
Owners: Bill & Charlotte Pratt
Architects & PH Consultants: HARRISON architects
Builder: Bonaparte Builders
Seattle, WA
Wauconda, WA
Bonaparte Passivhaus
HDD: 7,894
GFA: 1,430 SF
TFA: 1,107 SF
Walls: R-78
Roof: R-120
Floor: R-110
Windows: Ug - 0.09, Uf - 0.12, SHGC .50
Glazing Percentage: 39% of GFA
Heating System: 68 SF electric radiant mat (~1,100 w) in bath & entry floors
Wauconda, WA (Okanogan Highlands)
Madison Park Passivhaus
HDD: 4,720
GFA: 2,733 SF
TFA: 2,085 SF
Walls: R-52
Roof: R-62
Slab on Grade: R-26
Suspended Floor: R-53
Windows: Ug - 0.11, Uf - 0.17, SHGC .62
Glazing Percentage: 26% of GFA
Heating System: heated towel bars in baths
Seattle, WA
Thank you.
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