ENERGY AND DESIGN
Energy efficiency should be a prerequisite for any design, not an add-on. Conserving energy does not demand any particular style; rather it is a process starting at the beginning of design where the factors that affect use of energy are considered. The first and most cost effective step in energy savings is always conservation by using less energy. This includes basic planning considerations such as siting for passive solar, south windows, summer shading of windows to prevent overheating and efficient building shape to minimize exterior walls.
Next in importance are construction details with 3 basic considerations:
1) Insulation- More is better but there are diminishing returns for very high R values. R-30 for walls and R-70 for roofs are achievable with good payback. Higher R values may be appropriate for some projects.
2) Tightness- Build as tight as possible to prevent air infiltration and use heat recovery ventilation. "HRV" ventilation units transfer 70 to 90% of the heat in exhaust air to incoming air. Attention to air tightness also keeps moist air out of exterior walls preventing it from reaching a point that is cool enough to condense.
3) Water and vapor control- Build walls that dry out faster than they absorb water. In Minnesota this generally means drying to the outside and keeping moist interior air out of walls.
Building to the current energy code is not the best long-term strategy. "To code" has been termed the worst building you can legally build. For those who want to do better than the code minimum, there are a number of rating systems for new homes to choose from. Which is best depends on individual goals.
Minnesota Power Triple E Standards
Minnesota Power, the electric supplier for the Duluth, MN area has developed its "Triple E" standards for new homes. I recommend Minnesota Power's Triple E Tier I, or better Tier II, as a minimum standard for new homes. This is readily achievable with a small upcharge which will be recovered in a short time with the difference in energy use. This is an excellent, achievable standard emphasizing quality in construction and energy conservation. Any new home should conform to this as a minimum, preferably Tier II. http://www.mnpower.com/powerofone/one_home/new_construction/tierstandards.htm
If you believe, as I do, that energy costs will continue to rise, a standard such as the Passive House Standard should be used. This reduces energy use by a minimum of 80% with a goal of generating as much energy as the building uses over the course of a year: Net Zero Energy.
Passive House is a very detailed standard developed in Germany to achieve near zero energy usage. This ultimate goal may not be for everyone, but this is the direction we need to go. The emphasis is on energy use, super-insulation and low infiltration to cut heating and cooling loads. www.passivehouse.us
LEED for Homes
The US Green Building Council has developed a series of certification programs for various building types. A recent addition is LEED for Homes. It awards points in location and linkage, sustainable sites, water efficiency, energy and atmosphere, materials and resources, indoor air quality and education. Energy use is just one of a number of areas covered by this program. Whether certification is sought or not, LEED for Homes is a good resource for starting conversations on which sustainability goals should be pursued. www.usgbc.org
INTERESTING HIGH EFFICIENCY PROJECTS BY OTHERS
Passive House, Hudson Wi- Tim Eian, TE Studio
Hartley Nature Center, Duluth MN- Sanius-Johnson Architects