What is a passive home, and what does it have to do with environmental sustainability? A passive home or passivaus in German, is a house (any building can be passive with the correct planning) that is specifically made to be highly energy efficient, have a dramatically reduced carbon footprint, and a requirement of little to no extra energy for heating or cooling.
This idea began in the 90’s in Germany and quickly became more than just an idea. Two years after the two pioneers, Bo Adamson and Wolfgang Feist, had the first conversation about this idea, they had already built a set of four row houses in Darmstadt, Germany with the help of Bott, Ridder and Westermeyer architectural firm. This first set of row houses surpassed any expectation at the time, with energy costs being 80% less than standard houses built the same year. This is also when the Passive House Institute was created, which has helped spread the concept.
Instead of relying on the energy grid for power, a passive house uses the sources of energy surrounding it, such as sunlight, body heat, wind-power, ground heat (geo-thermal) and even the energy released in everyday activities such as cooking, cleaning and using appliances to heat in the winter and cool in the summer. The defining equipment in any passive home is the mechanical ventilation system. Since these homes have to be airtight, they need to be able to let in fresh air for occupants and release old air containing noxious gases and CO2.
The building envelope in these structures is truly remarkable; the walls are filled with extra thick insulation to minimize any chance of thermal bridging (heat loss). The windows are infra-red reflecting, vacuum sealed, triple glazed, triple pained and finally pumped full of the noble (colorless) gas, argon. This gas is heavier than air and acts as a better insulation against heat from solar radiation. The awnings on these homes are built to take advantage of the lower sunlight in the winter, and the higher sunlight in the summer. In some cases, the homes are so energy efficient that they sell extra energy from solar panels to the city or county energy grid; in fact, they get paid to do this. One builder in Germany, Rolf Disch, has built a set of homes that earn, on average, $5,075 per year. Typical homes in this area of Germany spend $4,500 and up on energy. Such a saving can really make an impact on a homeowner’s annual income and yearly spending. The positive aspect of saving money is enough for most people but for the more environmental conscious, the reduction in their carbon footprint is almost indomitable.
In 2010, there were over 25,000 certified passive homes in Europe , but only 13 of these homes in the US. The vast majority of passive houses have been built in German-speaking countries and Scandinavia. However, in the last two years, the amount of passive homes in the US has nearly quadrupled, due to higher energy costs and the stimulus packages that have been made available for “green building” through the Obama administration. The International Passive House Institute also provides additional information, as the US branch of Passive House. We hope this trend continues, as the homes are more energy efficiency that Energy Star and LEED certified homes – though these, too, are a great step in the right direction.