There has been a buzz within the design and building industry about Net Zero Energy Homes and for good reason. The California Energy Commission is recommending that all new homes be “Net Zero Energy Homes” by the year 2020 and all commercial buildings by 2030. As energy costs start to creep up, one’s energy bill will compromise a larger piece of your overall budget. Additionally, few know that the building industry is responsible for almost half of the greenhouse gases emitted as well as accounting for almost half of the energy used in the United States. These figures are more than those contributed by any other sector, including transportation. Ed Mazria, the founder of Architecture 2030, an organization whose mission it is to help stave off global warming by reducing the amount of fossil fuel energy used by buildings, opened my eyes to this sobering reality. (See 2030architecture.org for more).
Those of us in the building industry have a responsibility to design and build homes that are more energy efficient to help curb global climate change. Mazria feels that we can do this by reducing our reliance on fossil fuels by ten percent every five years and become carbon neutral by 2030. This goal will not be easily accomplished given the fact that worldwide emissions increased by 6% last year, the largest increase ever. If we don’t pay attention to the growing crisis, life on the planet will be in for some unsettling changes at a far greater rate than we currently experience. Richard Muller a scientist at U.C Berkeley and former skeptic on global warming science changed his stance and now believes that climate change is human-caused after heading up a in depth study.
What exactly is a Net Zero Energy Home? There are several definitions but the California Energy Commission defines it as a home that creates as much energy through on-site renewables (e.g., solar) as it uses. The home generates enough renewable energy on site to equal or exceed its annual energy use. If it draws from the grid at one point, it makes up for that by generating an equal or greater amount for use at other times, bringing the balance at the end of the year to zero or a positive balance. As the cost of solar panels continues to drop relative to the cost of energy, this scenario will become more affordable. When one throws in the true “costs” of global warming, it becomes more palatable. It’s high time that our economic perspective includes the “cost” of environmental degradation rather than ignore it. We continue to ignore these costs and do so at our own peril.
What’s the best path to achieving this net zero goal? To do it effectively, you’ll need to reduce energy demand as much as you can. The quickest path to creating a truly efficient home is to first focus your efforts on controlling heat loss and gain through your house by thoroughly insulating and sealing your building envelope. Until now, we’ve been designing and building leaky homes and compensated for poor building techniques by installing expensive, energy hogging mechanical systems. Net Zero Energy Home proponents advocate first minimizing the home’s demand for energy via insulation and sealing and then installing an appropriately sized, efficient and less costly mechanical system. Simple.
Not too long ago, while being interviewed for a new home project, the clients asked me, “What if we don’t want to build a sustainable house?” Their question points to a common, though understandable, misperception in the market: the idea that building sustainably has to an “add on” to standard building. While I would agree that there is a continuum along which you can build a sustainable home, the truth of the matter is that building a new home, or remodeling an old one to current code levels is akin to getting a “C” letter grade – you pass, but that’s it. The first metric of green design and building is durability. They say that if you double the life of a structure, you halve its environmental impact. Insulating and sealing your home is the least expensive way to achieve energy efficiency. We should be designing and building efficient, long lasting structures based on the principles of the latest building science. Homes that are easier to maintain, have healthy indoor air for our children and last longer. That should be the new passing grade.
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Theexamples below are entries in the 2011 Solar Decathlon.