I was surprised and pleased to see an article on the front page of the New York Times about the remarkably energy efficient Passive Houses. I have been following the German-born “Passivhaus” movement for quite a few years, but I hadn’t envisioned that there would be much enthusiasm in the U.S.—yet—for the extremely rigorous requirements of the Passivhaus standards. I must be wrong. For the next four days (Dec. 27 – Dec. 30) the Passive House article was the Times #1 most emailed story. During those days, I was getting multiple copies from every direction: friends, family, colleagues and even people I don’t know. It seemed that nearly overnight Passive House had entered the American vocabulary.
The Passive House (PH) concept is both brutally simple and extremely difficult. We have long known how to create an energy efficient building: face the sun; insulate, seal and mechanically ventilate. Passive House takes these rather obvious goals and establishes an extremely stringent standard for each of them, applying basic building science and its own tough formulas to set the bar at the very top of the green building stanchions. Moreover, it’s a pass-fail system; you achieve it or you don’t. It stands alone as the most energy efficient construction standard in the world. Over 15,000 Passive Homes have been built since the early ‘90s, mostly in German speaking countries and Scandinavia.
The main question I have been asked the past few days is how Zero Energy buildings, such as those (Unity House and Brightbuilt Barn) we built last year, compare with Passive Houses. The best answer, I think, is that they are perfectly complementary, not competitive. The ideal way to build a Zero Energy building is to start with a base building constructed to Passive House standards. From that platform, using renewable energy sources to get to zero (or positive) energy performance is made much easier.
Performance standards are set by the Passivhaus Institute in Germany. The building can’t consume more than 15 kilowatt-hours per square meter in heating energy per year (equivalent to 4746 BTU per square foot per year). This typically requires that the wall, roof and floor insulation must be between R40 and R60. The building can’t leak more air than 0.6 times the house volume per hour at 50 pascals of pressure, as measured in a standard blower door test. An energy recovery ventilator provides a constant, balanced fresh air supply, and may be outfitted with an electric resistant heater element to provide auxiliary heat in worst-case situations.
If the building clears the bar of the PH requirements, it no longer needs a furnace. The intention is to substitute the money spent on a heating system (along with the fuel to fire it) for money spent on insulation, careful detailing and good workmanship. Basically, it locks in heating and cooling fuel cost at zero. For the life of the building.
Why, then, isn’t everyone clamoring for it? I don’t know. We seem to have been born with a switch that allows us to turn off the memory of painful lessons that should have been learned; and with blinders that limit our ability to see that which is unsustainable when it is us. How else to explain the great interest in high performance buildings when fossil fuel costs were high only a few months ago, but now that the fuel costs have fallen, interest has suddenly waned? Is this short-term memory a defect in our species or just a peculiarly American defect? How did we come to make decisions in a dense fog, from which neither the past or future is visible?
I live in southern New Hampshire, near the Vermont border. In this area, the heart and soul of most towns are the many old houses, churches and town halls that were built 150-250 years ago. They remain in good service after many generations of use and remind us of the best of our capabilities as citizens, communities and builders. They are emblems from the past, but also beacons for a better future. If we could think and act with a vision beyond our own mortality, like the builders who constructed these enduring, defining structures, Passive Houses and Zero Energy buildings would now be much more common.
If a priority for high performance buildings doesn’t come from a social or ecological conscience—you know, looking out for the survival of our species, for instance—perhaps it would come from simple math calculations when our energy costs brutally and finally reflect their actual value.
What I hate to think about, but believe to be true, is that high fuel costs won’t really do it either. It will take a genuine crisis in which money isn’t the only issue. Just as you don’t get a new traffic light at an intersection until enough people have died in car crashes, it will take some large-scale disasters to give us the collective will to do something that is possible right now.
First, many people will have to suffer when an infrastructure entirely dependent on cheap fossil fuels completely collapses.
Then, higher standards will finally be mandated and people might at last be willing to give up flat screens and full-body showers for a home that will keep them warm and comfortable without any fuel whatsoever; in good times and bad, through decades, through generations, and on and on into a brighter future.
It’s such a good idea. Why don’t we just start doing it and NOT wait for bigger problems and human tragedies?