Dream house

Posted 8/21/12

I suppose most of us carry around a mental notion of the perfect house. I can’t remember a time when this idea wasn’t percolating somewhere in my consciousness, starting with childhood memories …

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Dream house

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I suppose most of us carry around a mental notion of the perfect house. I can’t remember a time when this idea wasn’t percolating somewhere in my consciousness, starting with childhood memories leafing through design magazines with my mother. We sketched numerous “perfect” houses over the years, just for fun, and exchanged photographs and floor plans, but I can’t recall that we ever thought about energy bills. Nowadays, I revisit the notion of the perfect house with my husband, especially during a tough winter. Only now, in addition to considerations of style, location and ample closet space, we dream of a house that performs differently. We’re dreaming about a passive house.

The “passive” in passive house comes from the use of age-old techniques based on the laws of thermodynamics, such as siting a building to take advantage of solar gain from southern exposures in the winter and shading in the summer. Thermal mass, another traditional strategy, is used to maintain temperature consistency for heating or cooling. In colder climates, concrete or masonry interior surfaces can absorb heat during the day and radiate it back into the living space overnight. In hotter environments, masonry or adobe walls can prevent daytime heat from penetrating into the living space, and radiate warmth during cooler, overnight hours.

Present-day passive house concepts originated in the U.S. in the 1970s and took root in Germany a decade later, where the PassivhausInstitut developed codified standards. Houses built to this standard use about 90% less energy for heating and cooling than a house built to typical building codes, because they use state-of-the-art insulation, windows and ventilation techniques. They reduce energy costs dramatically while providing far greater comfort and superior indoor air quality. Passive house technology paves the way for net-zero buildings, structures that generate renewable energy on site that is equal to or more than the amount of energy they consume.

I would have assumed that building to the passive house standard would be a lot more expensive, but in fact the building cost differential is minimal. According to the Passive House Institute U.S. (PHIUS), builders and architects trained in the concept can deliver a project for less than 5% more in building costs than a conventional structure the same size —costs that are quickly recovered through annual heating and cooling costs that average 70% lower than conventional buildings. Even when not built to strict passive house standards, any style and scale of structure—from single family homes to corporate headquarters, retail complexes or luxury hotels—can benefit from high performance building techniques beyond current code. The 1,800,000 square-foot 4 Times Square tower in Manhattan uses 40% less energy than the same building built to the New York State Energy Code, realizing annual energy cost savings of $1,760,000.

About 50,000 passive house structures have been built worldwide. New York City is looking to passive house to become their building standard, and eventually all U.S. building codes will mandate the passive house standard for new construction. A number of organizations are advocating for this change, and it was incorporated as a recommended policy change in Sullivan County’s Climate Action Plan. The European Union will require the standard for new construction by 2020. This, along with the increasing use of passive house standards for retrofits of existing buildings, will make it possible for us to fulfill almost all of our energy needs from renewable sources. Now isn’t that more exciting than granite countertops?

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