This article was originally published in the September/October 1993 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.
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Home Energy Magazine Online September/October 1993
Duct Fixing in America
by Cyril Penn
Ducts and thermal energy distribution systems are the new frontier in energy conservation. Several utilities are just getting started, while others are thinking about launching duct repair programs. Some utilities are taking a more cautious approach because the technology of duct sealing is still evolving. Currently there is little measured data demonstrating energy savings from large-scale utility duct repair programs.
Florida's utilities are very active in ducts. In early 1991, St. Petersburg-based Florida Power Corporation became the first utility in the nation to start a large-scale duct repair program, according to program manager Jack Davis. The utility completed 1,904 duct repairs in 1991, 7,000 repairs in 1992, and had logged 1,716 repairs through February 1993. The utility estimates residential customers in its 23-county service area have cut their annual cooling costs by an average of 17%, or $85 per customer.
Miami-based Florida Power and Light (FPL) introduced its Watt Saver incentive certificate duct leakage pilot program in February 1992, making it system-wide in June 1992. The utility tested 10,000 duct systems in 1992, completing nearly 4,000 repairs. FPL pays for roughly 50% of duct repair costs. Incentive dollars are tied to estimated hours of repair. All possible repairs are preassigned a time factor to standardize labor hours and expenditures. Average repair time is six hours. FPL's peak power reduction for 1992 was an estimated 1,750 kW. Senior Program Manager Holly Duquette says the utility is aiming to test 35,000 houses in 1993 and hopes to actually perform repairs in 60% of these homes.
Tampa Electric Company started a duct leakage program in September 1992, and by early 1993 had issued 1,000 incentive certificates and performed 150 repair jobs. The utility includes the duct check in its energy audits (using smoke sticks). Incentives offer $100 for minor repairs and $175 for major repairs like lining and sealing a return plenum. The average repair cost is about $300.
Georgia Power launched a duct sealing program for existing single-family homes last March, offering a $250 incentive per system. In multifamily buildings, the utility offers a $140 incentive per unit. In the first two months, the utility only sealed ducts in 135 homes, but the program is expected to mushroom. The utility has over 7,000 audits pending, and says roughly 55,000 units will be checked for leaks, though it's not certain how many customers will actually have their ducts sealed.
Another utility in Georgia--Oglethorpe Power--will probably start a program in 1994. Ogelthorpe, the wholesale power supplier to 39 of the state's 42 electric membership corporations, serves about 71% of the state's land area. The utility is testing 40-60 homes to determine the effects of duct sealing on peak load. The utility will justify the amount of rebate dollars it dedicates to repairs based on the results.
In California, both Pacific Gas and Electric Company (PG&E), and the Sacramento Municipal Utility District (SMUD) started duct repair programs. PG&E has been involved in pilot projects since 1990, launched a program for new construction in April 1993, and just started a retrofit program, targeting customers with high air conditioner usage--those who use over 2,000 kWh per cooling season (see The Appliance Doctor Programs, p.48). The average air conditioning consumption in these houses is 2,800-3,000 kWh. PG&E expects to reduce average household annual air conditioning electricity consumption by as much as 600 kWh in the retrofit program. Gas savings are expected too, but PG&E hasn't quantified them yet. From the new construction program PG&E expects 16%-17% cooling savings and 12% heating savings.
SMUD started a direct installation program this year. During regularly scheduled energy audits, currently limited to two hours, SMUD visually inspects and repairs any obvious leaks, tears or disconnections, at no cost to customers, adding insulation (to R-6) if ducts are insulated to R-4 or less. SMUD made a last minute decision to include duct repair in an existing program. We were planning to audit 4,000-5,000 units and didn't want to lose the opportunity, said Bruce Hayes, Supervisor of Residential Services at SMUD.
SMUD is considering a more intensive duct repair program, and is studying of 30 randomly selected homes in its territory with researchers from Lawrence Berkeley Laboratory. Thirty houses will be monitored before and after duct repair--15 homes in the summer and 15 homes in the winter. Roughly half will be gas, and half will be all-electric homes.
In North Carolina, Duke Power has a duct retrofit program (see Duke Power's Success, p.45.) In January 1993, the utility integrated duct sealing into its existing new construction program, known as New Max for Maximum Value Home. All ducts must be sealed and their performance tested with a duct test rig. Leakage may not exceed 3% of the floor area of the house at 25 pascals of pressure--a 1,000 ft2 home may not exceed 30 cfm. Duke Power plans to repair 4,000 units this year. Duke offers a $200 incentive for single-family housing and $100 per unit in multifamily dwellings.
In New Jersey, Atlantic Electric seals ducts as part of it's Energy Smart Service, targeting heat pump customers with comfort and high bill complaints (to prevent them from switching to natural gas). A free initial inspection includes a blower door test, a visual inspection of the ducts, and a heat pump test. For $120 (payable in monthly $10 installments--there's no interest) customers who need it are offered a package consisting of roughly 15 labor-hours devoted to blower door-guided air sealing, duct sealing, and heat pump tune-up. (The utility's actual cost of the basic service package is $600.) After testing duct sealing as part of its low-income weatherization assistance program, Atlantic Electric started offering duct sealing in August 1992. So far, the utility has performed 351 inspections resulting in 181 service visits in which duct leakage was reduced by an average of 20%-23%.
In Arizona, The Salt River Project and Arizona Public Service Company--are conducting a hundred-house demonstration project with Oak Ridge National Laboratory. The utilities plan to retrofit the houses, and collect submetered data, looking at energy consumption and demand reduction. Oak Ridge separately inspected two military bases as part of a project aimed at ensuring that energy-efficiency is considered during family housing rehabilitation. In this project, duct leakage was found to be the most serious efficiency problem.
In the Northwest, Bonneville Power Administration's Residential Construction Demonstration Program measured distribution efficiencies in 24 homes. Results should be published soon. We hope to take the recommendations from that program and integrate them into the Super Good Cents Program specifications, says Mike Lubliner of the Washington State Energy Office.
Pacific Power and Light in Portland, Oregon, is repairing ducts in all-electric homes through its Home Comfort pilot program. The program has reached about 500 homes so far. We're routinely getting reductions (in leakage) of two thirds with the blower door-flow hood method, said Bruce Manclark, a consultant who helped Pacific Power design the project. Elsewhere in the Northwest, Washington Water and Power is measuring duct leakage as part of a fuel switching program. Tacoma Power and Light and Puget Power are also measuring duct leakage in houses.
Energy Rated Homes of Arkansas tests for duct leaks in homes and recommends duct sealing to homeowners when it is needed. Energy Rated Homes of Arkansas offers training on duct sealing to contractors, according to Joe Kuonen, manager of training and inspections. Energy Rated Homes also trains contractors to seal ducts in some other states. Kuonen said Arkansas Power and Light is taking a look at the possibility of duct repair programs, and that Oklahoma Gas and Electric is also considering duct sealing for residential load control.
In Texas, the City of Austin (a municipal utility) is repairing duct systems in 125-150 single-family homes per month. The city plans to integrate duct repair into all of its existing conservation programs. Even the free weatherization program for low-income and elderly customers will soon include duct sealing, according to Doug Garrett, Senior Energy Coordinator for the City of Austin. Contractors are required to use manometers, blower doors, and mastics. Garrett said the average home in Austin has 25% air leakage through ducts (rated fan flow) and that after repairs, leakage is averaging 3%.
While the program hasn't been running long enough for the city to assess the energy impacts (it's been about one year), Garrett said he has no doubt we will have some good results from that sort of improvement. Austin is launching a pilot study of duct sealing in multifamily units and is begining to focus on ducts in its existing multifamily program. We're going to go from sealing the envelope to concentrating on sealing the mechanical system, said Bert Brown, Austin's multifamily incentive program coordinator. It seems like we're finally looking at the whole thing and not just whether the envelope is tight.
Figure 1. States with utility-sponsored duct repair programs.
Related ArticlesDiscovering Ducts: An Introduction
Duke Power's Success (Vigil)
Guidelines for Designing and Installing Tight Duct Systems (Stum)
Integrated Heating and Ventilation: Double Duty for Ducts (Jackson)
Leak Detectors: Experts Explain the Techniques (Proctor, Blasnik, Davis, Downey, Modera, Nelson, and Tooley)
Managing Large-Scale Duct Programs (Downey)
Mobile Homes: Small Zones, Big Problems (Kinney)
New Group Hunts Bad Ducts (Obst)
The New Monster in the Basement (Treidler)
One Size Fits All: A Thermal Distribution Efficiency Standard (Modera)
Stories from the Buffer Zone (Kinney and Stiles)
Two Favorite Test Methods, By the Book (Modera)
Will Duct Repairs Reduce Cooling Load? (Parker, Cummings, and Meier)
Infiltration: Just ACH50 Divided by 20? (Meier)
Pulling Utilities Together: Water-Energy Partnerships (Jones, Dyer, and Obst)
Recycling Refrigerators: Whose Responsibility? (Nelson)
Shade Trees as a Demand-Side Resource (McPherson and Simpson)
SMUD's Refrigerator Graveyard--Conditions of the Deceased (Bos)
Steps to Successful Lighting Programs (Fernstrom)
Wisconsin's 'Orphan' Solar Program (DeLaune, Bircher, Lane)
Beauty and the Beast Upstairs (Legg)
Selecting an Infrared Imaging System (Snell)
Sizing Up Skylights (Warner)
Telecommuting: An Alternative Route to Work (Quaid)
User-Friendly Pressure Diagnostics (Fitzgerald, Nevitt, and Blasnik)
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