By Terry Nordbye, West Marin Citizen, December 10, 2009
Community Land Trust Association of West Marin’s second community-owned home will aim to achieve maximum energy efficiency to help reduce global warming. (Photos by Marshall Livingston and CLAM)
We’ve all become more conscious about “going green” and benefiting the environment. When it comes to renovating an existing home or building a new one, there is a lot to think about. Although solar panels and bamboo floors can be an important element in green building, they can distract from what should be the primary goal – energy use, carbon production and global warming.
Amazingly, houses use 40 percent of the nation’s energy – more than cars and all other forms of transportation The average house, including ones built just last year, typically can waste around 30 to 40 percent of the energy they consume.
Common building practices do not pay enough attention to the ways that houses are energy guzzlers. Today, a house can be built or remodeled using green checklists for such things as low-VOC (volatile organic compound) paints, on-demand hot water, green-certified lumber, even passive solar and lots of insulation. But that doesn’t mean that it has been designed and calculated for optimal energy efficiency and performance. More importantly, the building and the installation of materials have to be done meticulously, conforming very closely to the energy design and criteria.
Finally, houses are not tested after they are built to see just how they perform. This means a new house can be rated as “green net zero,” but still be an energy guzzler. “Net zero” means that the energy a house consumes is equal to the energy it produces on site from technology like photovoltaic panels, solar hot water or wind. So if you install enough solar panels on the roof to balance out the energy wasted you can bring almost any house to “net zero.”
Is there a way to make an energy guzzler into a Prius? Yes, and it’s not rocket science, it’s building science. Building science uses fairly basic principles backed up by research and testing of how a building performs. Considerations include how things like pressure differentiation affects the heating and cooling of a house, the comfort level and air quality inside. Building science considers how moisture and/or heat travel through walls, and how thermal leaks affect heating and cooling costs.
Although insulation and heat delivery systems are not nearly as fun to contemplate as a roof full of solar panels that you can see as you drive by, they’re essential to our task of reducing global warming.
Lots of people have hopped on board, knowing that green building is “the right thing to do,” but the movement is in the early stages. We’re still learning the most important things to pay attention to.
Technicians on Tuesday seal up CLAM’s new house and de-pressurizing the inside to a specific value using a special “blower door,” in order to reveal the leaks and air infiltration as well as areas of insulation that are performing poorly.
For CLAM’s second community-owned home, in Point Reyes, we’re aiming for a renovation that will give the house the best energy efficiency and performance. Kevin Beck of Building Performance Services, a building analyst, consultant and educator, has offered to do free tests on the new CLAM house as we’re drawing up our renovation plans. The test will let CLAM know how the house currently performs as an energy consumer.
Energy efficiency test
The testing is interesting. Technicians seal up the house and de-pressurizing the inside to a specific value using a special “blower door.” Next we’ll take various readings inside the house and use an infrared camera to reveal the leaks and air infiltration as well as areas of insulation that are performing poorly.
Using the information from the tests, we’ll apply the appropriate building science techniques as we remodel the house. We would like to achieve a net zero house and the “test in” lets us know where to start. When the job is completed we’ll do a “test out,” to let us know how well we’ve done.
We are remodeling a Hummer into a Prius, and the future tenants – along with the community and the planet – will reap the benefits.
Certified general building contractor and certified green builder Terry Nordbye is currently working on his Building Performance Institute Certification. He is trustee on the CLAM board of directors