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
Who's Repairing What?
Duke Power's Success
by Frank Vigil
Frank Vigil is a senior project manager with the North Carolina Alternative Energy Corporation in Research Triangle Park, North Carolina.
Duke Power Company in North Carolina is one utility intent on improving duct efficiency in its service territory. In the Home Comfort Tune-Up, the utility targets all-electric homes with a mass mailing describing the program and its costs. Homeowners, if interested, reply by mail and an appointment is set up for an initial analysis by a contractor. The analysis costs $100, and half of this cost is paid by the utility. If it is determined that there's a need for duct repair, the utility pays up to 90% of the repair cost (up to a $230). The homeowner pays the balance. Some things--such as pressure relief and combustion safety--the utility will not pay for and this is outlined in the contractor's bid. Once the homeowner signs a work order, work begins immediately or an appointment is set for the repairs.
Because of the success of a pilot, Duke is starting a system-wide duct repair program. The utility plans to start slowly, completing 1,000 houses between June and December 1993. Plans for 1994 include diagnosing and repairing 5,000 houses with a ceiling of 12,000 houses per year beginning in 1996.
North Carolina Alternative Energy Corporation (AEC) played a key role in developing the program. We decided from the beginning to make the program performance-based, an essential move for truly attempting to reduce energy demand. The pilot program used blower doors and flow hoods to measure pre- and post-repair duct leakage. However, with the implementation of Duke Power's full-scale program, a switch to blower doors and a special duct tester is planned. This will provide more accurate duct leakage measurements, and allow utility representatives and contractors to identify the amount of leakage in the ductwork to the outside of the house (impacting energy) versus duct leakage to the inside of the house. With a performance-based approach, the utility is able to see if its goals are being met, contractors can determine if they're doing a good job, and homeowners know if they are getting what they're paying for.
Save the Ratepayers!
The top priority for the program is health and safety. Contractors are trained on issues pertaining to mechanically induced pressure differentials, combustion safety, indoor air quality, moisture, and house durability. If a health and safety condition exists or repairs will create a hazard (for instance, sealing the ducts will reduce whole-house ventilation to an unacceptable level), prior to performing duct repairs, the homeowner is notified before work begins. If the homeowner does not agree to remedial action as part of the repair job, a Stop Work notice is issued and the contractor leaves the job. If the homeowner agrees, a new cost estimate is prepared to include the health and safety actions. Then the work begins.
Here again, the performance basis for the program proves itself--contractors are required to measure pressures, infiltration levels, and carbon monoxide levels (where combustion appliances such as gas log fireplaces or kitchen ranges exist), and watch for unvented combustion appliances, moisture problems, chemical use, and any other signs of potential problems.
Schooling the Staff
The heart of a successful program lies in the training. Many programs around the country require little or no training. Meanwhile some schools claim to teach everything in as little as two or three days. North Carolina Alternative Energy Corporation's Duct Diagnostic and Repair School is quite intensive. Ten full days of training are required for successful completion. Five days of classroom and laboratory training are followed by five days of supervised field implementation. The classroom portion of the school is based on a program originally developed by Florida Solar Energy Center and it uses their manual, Duct Doctoring (see Resources, p. 65).
The curriculum includes two laboratories, an applications lab designed to teach students various duct repair techniques, and a second laboratory, an actual house where students practice diagnostic techniques. (AEC is constructing a two-story home located near the classroom that will allow trainers to recreate numerous diagnostic scenarios.)
Our curriculum also includes a week of supervised field work in actual houses participating in the utility program. Students work in teams of two or three and are accompanied by a trainer who assists them. The goal is for each team to diagnose and repair one house per day for five days. Each team gets a different trainer for each of the five days. Students must pass a final written exam. This, in addition to field evaluation, determines if a student has successfully completed the course and receives an I.D. card. Only contractors with I.D. cards are allowed to participate in the program.
Any utility contemplating a duct repair program must decide who will do the repairs. Several methods have been tried. Utilities that have hired general labor for the job have had great difficulties with their programs. Duke's program requires licensed HVAC contractors. A moderately skilled technician working with an installer usually has sufficient skills and experience to learn (and apply) the concepts. A trained contractor is required to be on the job at all times.
Answerperson on Hand
In the pilot program, trained utility personnel accompanied the contractors during the initial analysis, usually remaining on the job during repairs. Contractors benefited by having experienced people on hand during the analysis, particularly when unusual situations arose. Additionally utility representatives were available to answer homeowners' questions about the program, freeing contractors to work undisturbed. Because the very issue of duct leakage is relatively unheard of by homeowners, the presence of the utility person helped assure them they were getting honest answers and price quotes.
Duke Power plans to continue this close supervision it in its full-scale program, though it is unrealistic to expect a utility representative to be present at every home. Contractors that have demonstrated reasonable skills will be free to work more independently, and utility representatives will only need to provide spot checks. It's essential for the utilities to have enough trained staff to be able to both monitor and troubleshoot the program. Also a cadre of experts must be available to handle the particularly difficult situations that will occasionally arise.
Forms and Focus
A key element to any quality control program is form review. These forms enable a final quality control person to recreate situations in houses that have been worked on. Diagrams of the distribution system layout, checklists for each diagnostic and repair step, and blocks for before and after numbers help a form review person to quickly identify anomalies. Materials used, hours spent, leakages, pressures, and safety checks are all recorded by the contractor along with additional comments. Naturally these forms are only as good as the person reviewing them. It's important for the utility to dedicate a trained individual to quality assurance--including form review. (Proctor Engineering Group recently developed a computer program to assist with the form review process--see Managing Large Scale Duct Programs, p. 47.)
The program also calls for several focus group sessions with the participating contractors and utility representatives as the program grows. The intent is to help identify potential problems and new techniques and to allow for feedback among trainers, contractors, and utilities. Such feedback is an integral part of the program from the very first day of training. Positive reinforcement and quick feedback ensure that individual teams learn techniques and approaches from one another.
The results of Duke Power's pilot program were encouraging--enough so, that Duke almost immediately committed to beginning a system-wide program. Not only do they recognize the energy benefits, but also the public relations benefits. The response from consumers has been quite positive. A recent survey indicates that after duct repair, many customers are more comfortable, their utility bills are lower, and the indoor air quality is better.
There is still room for improvement. Duct repair in and of itself is not a high-profit center for any company. However, the diagnostic approach used in the program can often highlight additional needs that will increase profits. Ventilation; shading through the use of sun-screens; moisture removal strategies; additional insulation; and sealing bypasses--all can increase work and profit margins for contractors. Although trained to diagnose such things, the typical contractor is not trained to sell these services to homeowners. Many opportunities are thus lost and the contractor is limited to performing only basic duct repair. A study by AEC showed some contractors doing better at additional sales than others. Service agreements and equipment change-outs have been the typical sales so far, with only a few contractors actively promoting duct repair outside the Duke Power program as an adjunct to their existing business.
Analysis of 82 homes serviced under the Home Comfort Tune-Up pilot showed an average pre-repair duct leakage of 285 cfm50, and post-repair of 118 cfm50 (cubic feet per minute with the house pressurized to 50 pascals). The average costs for the analysis and repairs was $380 with the homeowner paying $70 of the total. Repairs consisted of duct sealing and limited equipment service only. Average repair time was under four hours for a two-person team.
Energy savings for the 82 homes were not measured. However, in 1992, AEC monitored five homes in Durham, North Carolina, looking at energy consumption for two months before and after duct repair. The average home used 13% less cooling energy after duct repair. We estimate that the corresponding reduction in heating energy demand after repair was 600-650 kW or 13%. These five homes were in better shape than typical homes, so it is safe to assume that the energy savings from duct repairs are greater in other homes in the area. n
Related ArticlesDiscovering Ducts: An Introduction
Duct Fixing in America (Penn)
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)
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