North American builders first began using the sun to effectively reduce home heating costs nearly five decades ago. With funding by the U.S. Department of Energy and the Canadian government, hundreds of "passive solar" homes were built in the American Southwest and in Canadian provinces. Essentially, the method involved siting a home in such a way that passive solar gain through large expanses of glass supplied enough heat to keep residents comfortably warm through the night. Heat was "captured" by thick masonry walls and quarry tile floors, and radiated into the air after the sun set. Other homes utilized trombe walls or "greenhouse" atriums to serve the same purpose.
In some geographic locations with abundant sunshine, passive solar homes were so efficient that residents never had to turn on backup heating systems, even during cold winters. But at the time, they were not necessarily highly energy efficient in other ways. A lot has changed since then.
Elements of Today's Passive House
Today's most energy efficient housing is much more sensible and highly efficient. Standards prescribed by the Passive House Institute of the US (PHIUS) include:
- Super insulation, with no thermal gaps, throughout the building envelope;
- Extremely airtight construction, with filtered ventilation;
- Installation of high-performance (typically triple-paned) windows and high-quality, insulated doors;
- Balanced heating and air-conditioning systems, and efficient ventilation to assure air quality;
- Site orientation and landscaping principles to maximize solar gain if and when appropriate, but minimize the need for cooling in warmer climates and hot seasons.
A quantifiable performance standard for Passive House construction takes into account the wide range of variables, not only of climate but also in market conditions and design preferences. The goal is to offer homeowners unmatched comfort, quality, efficiency and sustainability in the home environment, and to assure that the benefits are affordable both initially and over the long term.
A Unique Building Concept
Today sustainability and energy-savings in the home environment are mainstream concepts. Homeowners are increasingly concerned about saving money as well as saving natural resources and reducing carbon footprint while maximizing home comfort. Technology and manufacturing techniques have brought new efficiencies to the industry through better insulation, "cleaner" building materials, and more durable and eco-friendly home components. It's a new world.
Energy Star homes are rated between 20 and 30 percent more efficient than current code requires. With the additional of roof-top solar panels, the dream of owned a "Net Zero" home in terms of energy consumption has become a reality. A Passive House, however, offers even greater efficiencies, by achieving an overall energy consumption level 60 to 70 percent lower than the typical code-compliant home, in addition to consuming 90 to 95 percent less energy for heating and cooling. The Passive House standard "focuses on the house as a complete, airtight, highly insulated system that uses a very low level of energy per square foot while also improving the home’s indoor air quality."
The concept was pioneered in 1988 by a German physicist and a Swedish professor. In 1996, the Passive House Institute was founded in Germany. The US branch began certifying projects and training consultants in 2008. Rather than a brand name, it is a construction concept that can be applied broadly to both new construction and retrofit projects in order to produce homes that are highly efficient and ecologically sensible.
What the Future Holds
While new technology, sustainable materials and energy efficiency will continue to be primary concerns of homeowners and new home buyers, technology will also introduce new options. Selficient, an innovative building design firm, draws on the principles of Passive House design, but takes those principles several steps further. The company's self-proclaimed mission is "to not only make a positive impact on the environment but also on society."
The company's vision is for future homes that are biodegradable, easy to repair, quickly constructed and energy self-sufficient. In addition, the homes are attractive, individualized, sun-oriented and affordable. If that sounds like a dream, it is, but it's one of many. The future for innovation in home building has never been brighter.
Ongoing efforts to produce quality homes at affordable prices, to reduce energy consumption and the carbon footprint, to boost comfort and build "healthier" homes have room for a wide variety of new directions and many possible solutions.
Article is written by Gary Ashton.