Energy measures are the most cost effective sustainable building techniques to use. They usually provide a relatively quick payback, and, as energy prices soar, they will be in demand. However, some can be expensive. Often there are tax incentives and rebates available from local utilities for instituting these strategies, both for commercial and residential buildings.

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Energy Efficiency

There are several strategies that can be employed to increase the efficiency of a building and its equipment. We will highlight a few here.

The building envelope is probably the most important piece in determining how efficient a building is. The envelope is the outside “skin” of a building, and includes the siding material, vapor and air barriers, sheathing, wall studs, windows, doors, and insulation. Making sure that each of these is as efficient as possible is the key to lowering energy costs. Here are a few quick suggestions for improving the building envelope:

Siding – Should be installed overlapping to make sure no moisture or air can intrude. Caulk all joints and seal all penetrations.

Vapor and air barriers – These should be continuous throughout the envelope. Pay special attention to windows and doors and other penetrations.

Windows – Unless using passive solar heating, windows should have the lowest U value possible (U-value is the inverse of the R-value, or insulation value). Using coatings to reduce ultraviolet light and heat transmittance is also a good idea. Make sure the top and bottom flanges of the windows have flashings or ledges to avoid water intrusion. Seal all edges of the window frame.

Doors – Doors should have the highest insulation or R-value possible. Weather stripping around a door is a must to prevent drafts.

Insulation – Higher R-values are good, of course, but they come at a price. Thicker exterior walls are often needed to accommodate the extra thickness of the higher R-value insulation. Cellulose foam is a good substitute, though it is more expensive than traditional fiberglass batts.

Don’t forget to insulate in the attic and/or under the roof trusses. Blown in cellulose provides the best protection in an attic space, with rigid insulation or cellulose foam for under the trusses. The crawl space or basement should receive rigid or foam insulation as well.

Heating and air conditioning equipment get the most use and draw the most energy in the average home. Making sure that the HVAC (heating, ventilation, and air conditioning) equipment is efficient is a necessity. However, understanding all the efficiency ratings can be a bit confusing.

AFUE (Annual Fuel Utilization Efficiency) – This is applied to gas furnaces, and the higher the number, the more efficient the unit. Energy Star requirements for Oregon recommend an AFUE of 90% or above for gas heating equipment.

SEER (Seasonal Energy Efficiency Ratio) – This number corresponds to the efficiency of electric cooling equipment, like air conditioners. Energy Star recommends a SEER of 13 or higher. Units are now available with SEERs of 17.

HSPF (Heating Seasonal Performance Factor) – Used for electric furnaces and heat pumps. An HSPF rating of 8.0 or above is recommended for Energy Star homes. Appliances should be as energy efficient as possible. Energy Star ratings are generally a good measure as to how efficient an appliance is.

Water heaters, however, have their own system (of course). It is called the Energy Factor (EF). Gas tank-style water heaters with an EF of .61 or above are considered efficient, while electric tank-style water heaters should have a rating of .93 and above (according to Energy Star requirements for Oregon).

On-Site Generation

Another good way to save on energy costs is to generate it on-site. Electricity can be created through wind or solar power (even in rainy Oregon). Both have great incentives through tax credits and rebates, which should pay for half the cost of the system, or more. However, on-site generation systems are expensive. Oregon is a net-metering state, which means that if the generation system is connected to the power grid, and it generates more electricity than is used, the meter will actually run backward, and the owner will essentially be “paid” for the electricity contributed to the grid. These credits for “over generation” can help to offset the costs of other times, when not much energy is generated.

Renewable Energy

When on-site generation systems are not an option (either physically or economically), building owners can always invest in renewable energy. There are two ways to do this, depending on your utility company:

If your utility company provides the option to purchase renewable energy directly (PGE does this), then you can simply elect which renewable options you want to invest in (hydro, wind, solar, and geothermal are the choices furnished by PGE). These programs will cost more per kilowatt hour, but the additional funds help develop the infrastructure for harvesting renewable energy.

If your utility company does not offer renewable energy options, you can always purchase what are called “Green Tags.” These work basically the same as the option from the utility company, in that you purchase so many kilowatt hours or therms (measurement of natural gas use) of green tags, and the money goes to support development of renewable energy options. There are many companies offering these tags (some of which are more reputable than others). Make sure that the tags are Green-e certified, which confirms their authenticity.

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Green Building Guide 101
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