Raising Standards and Savings

New Group Hunts Bad Ducts

by Jim Obst

Does 40 billion kWh sound like a lot of energy? How about 4 billion therms? Researchers believe that's how much electrical and gas energy this country could save by fixing inefficient ducts using current techniques. Refining those techniques could reap savings of 90 billion kWh plus 9 billion therms! Peak loads would be reduced too. To pursue these tremendous savings, national, state, and utility research laboratories, the U.S. Department of Energy, utilities, and energy service companies are collaborating. Their consortium is called Residential Energy Efficient Distribution Systems, or REEDS.

The members of the collaborative have mapped an ambitious program that includes: learning what kinds of thermal distribution systems (principally ducts and radiators) exist in the United States, establishing a universal yardstick for energy efficiency of those systems, designing tools to measure that efficiency, and establishing how best to build and repair thermal distribution systems. It's an ambitious program that's hard to see the end of, but the rewards will be monumental, declares Jim Cole who heads the California Institute of Energy Efficiency. Cole has been the facilitator of REEDS.

Stock characterization. For all the houses in the country, REEDS studies will determine which have heating or cooling ducts, where they are placed within the building envelope, what they are made of, and how they were installed. This stock characterization will help delineate the enemies of duct efficiency--heat losses or gains from leaks and conduction.

Stock characterization can help utilities and state institutions plan and evaluate duct repair programs. In Florida and California, where researchers already have a good picture of ducting, the goal is to measure actual savings from duct retrofits. In the Northern states, however, researchers will gather basic thermal distribution data.

Figure of Merit. Studies show that nationally, duct efficiency may be as low as 60%-70%. Ducts have remained an invisible energy culprit because of difficulties in isolating duct losses from energy losses in heating and cooling equipment and in buildings. Influences like system location, climate, and fuel mix confound the picture of the role of distribution systems in efficiency. A yardstick , or Figure of Merit (analogous to AFUE ratings for furnaces), for the energy performance of ducts alone and as they relate to other influences looms as a key goal of REEDS (see One Size Fits All: A Thermal Distribution Efficiency Standard, p. 62).

Diagnostic Tools. To arrive at the Figure of Merit for each class of distribution system, practitioners need simplified field measurement protocols and equipment. Such new diagnostic tools could assess the performance of distribution systems and judge other methods for fixing energy losers. The REEDS consortium wants to compile a list of current diagnostic techniques for evaluating duct efficiency, compare them to each other, propose improvements, and standardize those techniques.

Retrofit and Construction Methods. Once a Figure of Merit says what an efficient duct looks like and there is a standard way to measure duct efficiency, the next goal is to build or retrofit ducts to meet such standards. REEDS will help develope new ways to install and fix ducts that, it is hoped, will become standard practice. Another product of the REEDS collaboration would be valid performance measurements and commissioning techniques for finished homes.

Education and Training. Once the country reaches the lofty goal of 95% thermal distribution efficiency in new construction and 80%-85% in retrofits, a qualified body of field practitioners would maintain those levels of performance. REEDS wants to establish channels to the field for transferring the results of its research on ducts.

Cole is quick to point out that the rewards are great, but so are the costs. Saving millions of kilowatt-hours depends upon substantial financial commitments. The research programs require $2 million per year. Initial commitments to selected programs have come from members of the Association of State Energy and Technology Transfer Institutions (including the California Institute of Energy Efficiency), the Electric Power Research Institute, and the U.S. Department of Energy. Cole hopes that other leading electric and gas utilities as well as research and development organizations will financially support REEDS programs.

The distribution system has been left out in the study and practice of energy efficiency, until now, says Cole. That's about to change radically. The inefficient duct will be a thing of the past when we're done.

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