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Technology Corridor

It's not just for enviros any more.
Fortnightly Magazine - April 1 2003

that's because buyers generally assume that if a building meets the minimum standards for the local energy code, energy efficiency is taken care of. But a June 2002 study of new home construction in Ft. Collins shows that simply is not the case there.

The study documented numerous cases in which vapor barriers were lacking, ductwork leaked excessively, and insulation was improperly installed in homes built from 1994 to 1999. Indeed, in one case a 1999 home completely lacked attic insulation, due to builder oversight-and cost the owner $150 more in energy costs over six months, until city officials discovered the problem after three failed visits from the builder.

According to Swartz, another part of the problem is that many popular architectural features, such as cantilevered floors and living space over garages, can be highly inefficient from an energy perspective (see Figure 2). Those features can be incorporated into a green building project, but the builder needs to ensure that construction methods don't unintentionally cause energy loss, through improper insulation techniques and the like. Also, Swartz notes, many builders pay little attention to the solar orientation of a house, even though a vast expanse of glass facing south can lead to significant solar heat gain-driving up the need for air conditioning during the summer.

The desire to decrease peak kilowatt demand is what drove FCU to start its green building program, along with the municipal utility's interest in the well-being of the community they serve, Swartz says.

Meeting Conservation Goals

Over time, green building programs can indeed shave peak demand significantly. Xcel Energy started its program in Minnesota a decade or so ago, when it was Northern States Power Co. Over the last 10 years, the company has avoided 62 MW of peak demand-the size of two to three small peakers, says Julia Gauthier, product portfolio manager at Xcel in Minnesota.

Xcel's program focuses solely on commercial-type buildings, particularly those 50,000 square feet and over. The company offers free design assistance to its commercial customers, sending representatives from an energy consulting firm to meet with the building owner, architect, and engineer to review the initial design plans. After evaluating aspects of the initial building design such as shape, size, orientation toward the sun, and windows, the energy consultants predict the energy usage of the initial design, including annual energy costs and peak kilowatt demand. Along with this energy modeling comes a number of suggestions for altering elements like lighting technology, window type and glazing, adding more daylight, and using lighting controls.

Typically, the energy consultants present three bundles of options for changes, with three price tags and impacts on energy savings. Once the building owner and design team select the options they want to pursue, Xcel calculates the peak kilowatt savings. For those buildings that will save up to 28 percent in energy consumption over standard energy code, Xcel pays the owner $170 per kilowatt-hour saved. To provide additional incentive, the utility offers bigger rewards to those building owners that exceed the 28 percent energy savings mark. Xcel pays builders up to