BuildDirect Blog: Life at Home

Green Building: the Passivhaus Standard

the Passivhaus (aka “passive house”) standard is the construction technique of the future, reducing utility bills by 90%! As energy prices rise, buildings will have to be more efficient. There is no excuse to not build a green home, and the Passivhaus standard is the best choice.

Passivhaus sectional diagram 300x235 Green Building: the Passivhaus StandardConstruction features of passivhaus building

  • Compact size – 50 square meters (approx 538 sq ft) per person
  • Super insulation of floors, walls and ceilings
  • Air-tight envelope with no thermal bridging
  • High-performance doors and triple glazed, insulated frame windows
  • Heat recovery ventilation (HRV)
  • Passive solar
  • HERS score 20-30
  • PHPP Certification (Passivhaus Planning Package)
  • Space heating must be no more than 15 kWh/sq m (4.75 kBtu/sq ft)

Overall energy use must be no more than 120 kWh/sq m (38 kBtu/sq ft).  HRV air exchanges must be 0.6 or less per hour at a pressure rating of 50 Pascals.

Benefits of passivhaus building

  • Improved indoor air quality
  • Increased physical comfort
  • 90% energy reduction
  • Minimal conventional heating system
  • Suitable for retrofits
  • Affordable

The point of passivhaus construction is to minimize energy loss by restricting airflow into and out of the building. The building stays warm in winter and cool in summer. Style does not matter, as long as the efficiency and air circulation goals are achieved.

The envelope is super-insulated, up to 16″ beneath the slab and in exterior walls (R 60-70). Strawbale, SIPs and ICFs (insulated concrete forms) or Rastra are suitable. Ceiling insulation of dense-pack fiberglass, cellulose or spray foam has an R-value anywhere between R 60-100.
The triple-glazed windows have a very low U-factor of 0.14. Some in Germany are as low as 0.17. The U-factor rating of the National Fenestration Rating Council (NFRC): the lower the number, the more efficient the window, based on the glass, frame and spacer material.
Thermal bridging is essentially eliminated. A blower door test is run several times during construction to test for air leakage before the building is completely closed up and finished.
A heat recovery ventilator (HRV) keeps indoor air fresh, exchanging indoor air with outdoor air with minimal heat loss.

Energy savings in passivhaus construction

Passivehaus themogram 300x189 Green Building: the Passivhaus Standard

An example of a thermogram, testing for heat loss.

Because passivhaus construction is performance-based, buildings are monitored after final construction. The CEPHEUS project monitored 250 passivhaus’s in the EU, and their results showed an energy reduction of 90% on average.

I have heard varying estimates of the extra cost to build a passivhaus in a range of 5-10%. This is offset quickly with the huge energy savings. The payback period depends on each individual home’s energy use. Passivhaus construction is not catching on quickly in the US, and education is key. Components are available, so homeowners need to be aware of its benefits, and builders need to learn how to build these homes.

The addition of solar and wind power can turn a passivhaus into a net-zero home, but the energy creation and consumption of passivhaus construction is meant to be just that – passive. To me, that is a gentler way to live, and there are no moving parts to maintain. A 90% reduction in the energy consumption of a passivhaus is good enough for me!

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Nan Fischer

Nan Fischer has been living and building green for over 35 years. She writes from personal experience and backs it up through her extensive resource library. Nan’s emphasis on the BuildDirect blog is about how to make your dollar stretch further, while also moving toward a more sustainable lifestyle. She is a major contributor to the BuildDirect green blog. Nan also blogs on the website of her seed business, sweetly seeds.

8 Comments

  1. Nan,

    Love the post and outline of the standards. I was curious, do you think Passive House will be something that can be branded well enough so that homeowners will demand it? I wonder if we should try and be setting it based on comfortable ( a luxury) instead of monetary value ( a commodity)?

    Chris

  2. Hi Chris,

    Thanks! I think Passivhaus is the future. It is THE most efficient way to build right now. We need for the economy to pick up and see how the construction industry changes, but I think people will demand more efficient homes. If they can understand the savings over the small extra cost to build, they will be ok with it. We also need to educate them on the improved indoor air quality and comfort. I think the two go hand-in-hand, but the bottom line is education. The word needs to get out there, and people need to see proof that this is the most efficient way to build. I do more educating than anything these days. Does that answer your question? Let me know!

    Nan

  3. Nan,

    I does. I think it will be critical to see the air quality and comfort over savings. People always value luxury more then cost. What do you think?

    Chris

  4. I think they want convenience AND comfort. They don’t want their lifestyles to change. People are afraid that with solar, for instance, they have to fuss with batteries or panels or electricity or whatever, but that’s not the case. You live in your house like any other house. People need to understand that, even though that was not the case 30 years ago. That image of a rooftop batch solar hot water heater is in their heads and hard to change.

    With Passivhaus construction, there are no changes to your lifestyle. It’s in the construction. And being a performance standard, it is monitored for energy usage after the building is done. It’s monitored all through the construction, too, so there are really no surprises once you’re living in it with low utility bills.

    With modeling nowadays, too, you can know exactly how your home will perform. Before the site is even prepared, the homeowner already knows what to expect.

    Showing people in black and white – charts, analyses, modeling plans, energy audits and the actual results of other passivhaus’ – will let them know what a benefit passivhaus construction is.

    I love your blog! I just checked it out. Nice work!

    Nan

  5. Good concise summary. Could I just suggest one thing though, this line: “HRV air exchanges must be 0.6 or less per hour at a pressure rating of 50 Pascals” is not quite correct – the 0.6ach is the requirement for the blower door test (ie a measure of how tight the fabric is), the HRV should be providing the correct air changes for ventilation.
    best wishes, Elrond

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