A passive house is a living structure designed to recycle and trap heat. It is essentially built as a highly insulated enclosure with a special ventilation system that transfers warmth lost from the outgoing hot air to the incoming cool air. The owner is reducing waste and conserving a significant amount of thermal energy – these types of homes have been known to reduce heating bills by up to 90%, as they don’t contain any specific heating element. All heat comes from intrinsic sources of energy such as lighting, appliances, and the human body. Passive homes were originally pioneered in Germany, and are already popular in Europe and becoming more so in the United States. Below is a recent video which was posted in the New York Times Business Section in September 2010 which tells the story of a New England family who designed and built their own passive home.
Long term economic outlook
I thought it was interesting to note that according to the video, the cost of building a passive house in Europe in 2010 can be as little as 2-3% greater than building a traditional house (without these energy efficiency features), compared to the 15-20% increased cost in the U.S.. Therefore it is more expensive to build a passive house in the U.S. than in Europe. Assuming current price stability over the next decade (which is unlikely), passive homeowners in America will generally make up for the cost difference in 10 years through energy savings. I found the topic of passive homes first discussed online in the Times in December 2008, in a fantastic article entitled “No Furnaces But Heat Aplenty in Passive Houses” – however, I credit first hearing the about concept and construction of passive homes in 2006 from a German girlfriend. The 2008 article quotes the cost of building a passive house in Germany as 5-7% more than a traditional home. So, in Germany the costs for building passive homes have dropped 50% in the last two years (which is great news)! If the U.S. were to experience a similar trend in the coming decade due to increased demand and improved supply chain efficiency and production of raw materials, the cost of building passive houses could proportionally fall here as well, potentially allowing American builders to recoup costs within just 5 years.
U.S. government promoting energy efficiency at home
The U.S. Department of Energy published an article Building America Research in Action: Air Sealing in Existing Homes in their Building Energy Efficiency News, part of the Building Technologies Program and greater push towards Energy Efficiency and Renewable Energy (a great website). The mission of the Building Technologies Program (BTP) is to develop technologies, techniques, and tools for making buildings more energy efficient, productive, and affordable. In the coming century, as the demand and cost of energy rises, homes which use less energy and conserve more will provide their inhabitants with greater and greater cost benefits- making the passive house a smart long term investment.
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| Above is the interior of a Passive House at Darmstadt Kranichstein, published by the Passive House Institute in Germany. Each passive house has the following characteristics: optimal solar alignment (i.e. solar building design), superinsulation, advanced window technology, airtightness, high efficiency natural or mechanical ventilation, and heat recovery systems. There are many different design features available, but the general schematic is to the right. In a nutshell, a special air circulation system is used to recover the thermal energy. This can be accomplished by a mechanical High Efficiency Recovery Ventilation (ERV or HRV) system which are over 90% efficient. |  |
Thermal energy recovery using an erv
As of January 2010, there was only one Energy Recovery Ventilator actually made in the United States, the RecoupAerator 200DX by UltiamteAir. This machine is attached to the duct work of your home and exchanges the entire air of the house every 2 hours. The incoming air is run through a filter removing spores and pollen, which is why passive homes have especially clean air, while outgoing air exchanges its heat and moisture with the incoming fresh air.
RecoupAerator 200DX
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It is possible, with enough motivation, awareness, and financial support through tax-credits that the building and re-modelling of most new houses could be accomplished in this manner. The desire to create a home which is essentially energy independent, clean, and green can now be accomplished and is being implemented by builders all over the U.S., especially California and the Northwest. A final comment I heard, was that perhaps specialized, more favorable mortgages could be designed for homeowners who adhered to the standards of ultrahigh efficiency passive homes to help defray the increased up-front costs.
Additional Information
The 100K House – Passive House (Passivhaus) Standard for Energy Efficient Design – April 10, 2008 – 74 comments
The Eco-House Manual by Nigel Griffiths