Passive House In Depth for Professionals

the ‘passive house’ energy design standard

Dylan Lamar, BSCE Architecture Graduate Student

making a leap toward carbon-neutral buildings

Source: Intergovernmental Panel on Climate Change

Countering global warming requires rethinking every facet of human society.

Source: UN Environmental Programme

Source: Architecture 2030

the ‘passive house’ energy design standard

an energy efficiency design standard (and methodology) achieving 90% reductions in space heating energy, and 70% reduction in total building energy use.

“Passive House?… didn’t we already try that back in the 80’s?”

•From German: “Passivhaus”

•Not limited to houses

•House as Passive Machine (not confined to passive solar concerns)

Source: Passivhaus Institut

built examples in europe…

First Passivhaus, Darmstadt, Germany, 1991

Supermarket

Office BuildingSingle-Family House

built examples in Europe…

Manufacturing PlantAustria

Apartment buildingCologne, Germany

built examples in Europe…

GymHeidelberg, Germany

SchoolWaldshut, Germany

the concept

Concept Origin: “Tunneling through the cost barrier” –Amory Lovins, Rocky Mountain Institute


the concept


ACTIVE vs. PASSIVE

the standard

•Heating Energy Use < 15 kWh/m2yr (4,750 BTU/ft2yr)

•Peak Heat Load < 10 W/m2 (3.2 BTU/hr.ft2)

•Airtightness: n50 < 0.6 ACH (a typical residence is 5)

•Total Primary Energy Use < 120 kWh/m2yr (38,000 BTU/ft2yr)

“A building which can meet its heating and cooling needs solely through conditioning the incoming fresh air volume required for good indoor air quality”

design principles

First Minimize Losses…•Superinsulated & Airtight Envelope without thermal bridges•Heat Recovery Ventilation, >80% efficiency

Then Maximize Gain…•Passive Solar Gain (often optional)•Technology can easily be added in the future


design principles: minimize losses

1. Continuous Insulation- creating steady indoor temperatures that won’t drop below 50 degrees without heating source

2. Airtightness- minimizes moisture diffusion into wall assembly

3. Thermal Bridge Free Construction- minimizes condensation/ building deterioration

4. Balanced Ventilation with Heat Recovery- exceptional indoor air-quality



Source: e-colab

optimize the building… …to the heating system

the “gas mileage” of a building:


Source: e-colab

…not the heating system to the building.


Heat Recovery Ventilation

the result


the method

The “Passive House Planning Package” (PHPP) •An Excel-based steady-state energy design program•Extremely detailed•Calculations are transparent and customizable

the method

Empowering building designers with the necessary information to make the best decisions.

a tour of Passive House design and construction…

•Generating form based on energy concerns -Compactness -Glazing Area

•Detailing the Continuous Thermal Envelope -Eliminating thermal bridges -Achieving airtightness

•Simplifying the mechanical system

generating form: compactness

Model A

• 1500 sq ft, Single-Story, 30’ x 50’ rectangular plan (Envelope Area-to-Floor Area Ratio, EA:TFA = 3.9)• South glazing 10.8% of floor area.

Model A as a Passive House

• 1500 sq ft, Single-story Home (EA:TFA = 3.9)• Walls: 16” TJI Framing with Cellulose Insulation (R-58)• Roof: 24” Cellulose (R-86)• Below Slab: 12” EPS Styrofoam (R-47)• High-Performance Triple-Pane Windows w/ Insul. Frames

South: R-6.3 (U-0.16), SHGC=0.61Other directions: R-8.3 (U-0.12), SHGC=0.37

• High-Performance Insulated Doors (Air-tight)• Continuous Air Barrier w/ Heat Recovery Ventilation (>70%)

• Auxiliary Heating Source:

Max Heat Load is about the same as the output of a large hair dryer

A three-fold decrease in space heating energy use from a superinsulated envelope with only “high performance” double-pane windows.

Model B

A two-story version of Model A…

1500 sq ft, Double-story 25’ x 30’ (EA:TFA = 2.9)

Exact same windows and doors as Model A.

Model C

Rowhouse of Four 1500 sq ft, Double-story apartments, 100’ x 30’ (EA:TFA = 2.2)

Slightly less southern glazing (8.3% of floor area), no east/west windows or doors.

This 4-unit Row House is 27% more compact than a stand-alone unit would be, but has 85% less space heating energy use (given the same insulation and windows).

This allows insulation levels (and construction costs) to be decreased while still meeting the Passive House Standard…

In fact, at this scale, insulated window frames are no longer necessary, and non-south facing windows can be double-pane, low-e (but south-facing glass must still be triple-pane).

Compactness Study…

generating form: compactness

Other issues:

•Compactness is not always intuitive, especially as building size changes.

•Compactness should not preclude daylighting and natural ventilation.

•Architects must accept that if we intend to burn fossil fuels to condition our buildings, we must also accept our responsibility to create a conservative form.

•We must accept the limitations of compact forms as a direct result of the limitations of renewable energy resources.

the continuous thermal envelope

Source: e-colab

Floating slab allows continuous insulation

passive house news…

Source: e-colab

Source: e-colab

Passive House framing with TJI’s

12” Trusjoist TJI’s as wall studsSource: e-colab

Source: Manfred Brausem


Source: e-colab


Source: e-colab

Insulated header above window Source: e-colab

Source: e-colab

superinsulation without thermal bridges

Miscellaneous Details…

Wall/Roof Jog

Door Threshold

•Minimize roof penetrations by combining all plumbing fixtures to one vent

Source: e-colab

window issues…

•Triple-pane with insulated frames•Inset within wall profile

Continuous air barrier is applied to achieve…

…Air Leakage (@ 50 Pa) of less than 0.6 house volumes per hour

airtightness…

simplified mechanical system

The “magic box”Source: Passivhaus Institut

simplified mechanical system

Because windows are so efficient, there is no need to locate heating registers adjacent to them, thus duct runs are shortened.

•Ventilation ductwork fits within 2x4 wall

Passive House development…

CEPHEUS Project of 1999-2000

passivhaus development…

Renovationproject

Apartment building

“Passivhaus” turns “Passive House”

The BioHaus at Concordia Language Center, Bemidji, Minnesota, 2006

the passive house & affordable housing

www.e-colab.org

Prefabricated Panel Construction

the passive house & custom housing

Passive Conservation(Envelope Investment)

Active Generation(Solar Collector Investment)

Where is the optimum point on this spectrum?

Taos, New Mexico


October 19, 2007… Winner of the Solar Decathalon:Technische Universität Darmstadt

passive house development…

Conclusions

•We cannot talk of sustainable development without solving the energy issue.

•Piecemeal improvements will not get us there in time to prevent catastrophic climate change.

•The Passive House method is the most ambitious and most verified energy efficiency design method

•Given the Passive House methodology, architects are empowered with the necessary tools to make the right design decisions.

For more information:

www.passivehouse.us

[email protected]