Building energy efficient homes

Building energy efficient homes is not a new idea, just one that needs to be redefined. How efficient should a home be? What methods and materials should be used? What defines an energy efficient home over a standard built home? How much should an energy efficient home cost? I will attempt to answer these questions in future blogs as I continue to build homes of this nature, I have been doing this for some time now and continue to get better with each home I build.
For me the process of building efficiently starts in the design and continues throughout the process. Each choice made during the process has an impact on energy, whether it is the energy needed to build it or the energy that is consumed over the lifetime of the building. The energy consumed over the lifetime obviously has a larger impact for the occupant and should be IMHO the focus of choices made. While the cost of building a home should and always is the primary focus in the beginning it is only the starting point to build from. By using energy modeling during the process you can quickly define the cost benefit of choices made. Things like, if I double my insulation value of my walls how much energy can I save annually or over a ten year period, this is a great way to assist in the decision process. If you can say that doubling the insulation will cost, say $3,000 and the annual energy savings will be $1,000 in heating and cooling cost this to me is a no brainer. But if the savings is only $250 annually then the choice is a little tougher to make especially if the budget is tight. How about windows? should I use a super energy efficient ones if the increase in cost is $6,000 and the energy savings is only $400 annually? All of these choices need to be made in the design process, long before construction begins.
Right now I am designing a home with a building budget of $150,000, how efficient can I make it and what areas of the home should be the primary focus to meet the goals of the project. For me the answer is simple, Insulation and air sealing is always the best bang for the buck. After having done the energy analysis on several types of homes, using different methods of construction the answer always comes out the same. Well insulated and air tight homes have the largest impact on heating and cooling loads not only reducing the cost to operate these systems but typically reducing the size requirements to meet these loads. Smaller heating and cooling systems cost less to operate and usually cost less to buy and install. In most cases the cost increase to add more insulation and air sealing is saved in the system costs without adding to the budget cost.
I like building homes with Structural Insulated Panels (SIP's) for several reasons. First they have a very high R-value over conventional construction with minimal cost increase. For me the cost come out about the same after you factor in labor savings of building with a prefabricated wall system. Secondly they have minimal thermal bridging, a key component of heat loss in a building. Third air tightness, SIP's build a tighter enevelope that has very little air leakage if properly installed, so tight infact that you need to add air to the builing to maintain indoor air quality. A typical SIP's home needs to have a HRV/ERV system to provide the home with quality air without heat loss. A home build with SIP's here in New England typically save 30-50% annually on heating and cooling and add less than $5,000 to the building costs even when an HRV is added to the home. Not only saving a thousand dollars or more in costs annually but add comfort to the home with less drafts and superior air quality.
I will continue to post more about these methods and ideas over the next few months or you can find out more information about other means, like passive solar energy on my other blogs and my website, www.eebt.org

More to come in the near future stay tuned for the methods used to create homes that use less energy and are cost effective to build.
Thanks Tom Pittsley
ecobuilder@aol.com
www.eebt.org