Saving energy has become more important than ever, according to the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). Communities across the nation are starting to adopt energy-efficient building codes. What do HVAC contractors and the public need to know?
"Rising energy costs encourage higher efficiency," commented Charles Culp, Ph.D., P.E., associate director of the Texas A&M University System Energy Systems Lab and Mechanical Engineering Dept, College Station, Texas.
"In the past, consumers have shied away from purchasing more energy-efficient equipment and taking more efficient measures due to the initial higher cost," he said. However, "As energy costs continue to increase, homeowners are learning that becoming more energy efficient results in a net cost savings, even when the cost of the higher efficiency equipment is included."
Culp is chairing ASHRAE's public session, "Improving Residential HVAC Energy Efficiency." It will take place from 3 to 5 p.m. Monday, Jan. 26, at the Anaheim Convention Center. Admission is free and registration for the Air-Conditioning, Heating, Refrigerating Exposition (AHR Expo) or the ASHRAE Winter Meeting is not required. The session is sponsored by ASHRAE's technical committee on residential and small building applications (TC 09.05).
The session will focus on major areas of achieving energy efficiency in residential construction for both new and existing housing.
The subjects to be covered and the speakers scheduled are:
Problems And Solutions
"Take the time and effort to ensure that the charge and airflow are right," said John Proctor, when asked what primary message he would want contractors to remember from his portion of the program.Proctor is the principal and managing partner of Proctor Engineering Group, an energy efficiency and quality assurance demand-side management consulting firm specializing in design, implementation, training, and evaluation of programs directed at bringing the performance of new and existing equipment up to its efficiency potential.
The three biggest residential HVAC problems, according to Proctor, are:
1. Too low or too high of a refrigerant charge.
2. Inadequate airflow across the coil.
3. Duct system problems (leaks, crimps, etc.).
Commercial jobs also add economizer problems to this list, Proctor said.
In order to make sure the work is done right, HVAC contractors need some sort of "quality assurance mechanism," he continued. In order to prevent problems that lead to undue energy consumption, contractors need to "review the work on every job each technician did."
While this task may sound impossible, Proctor said there are relatively low-cost ways of doing this. "What's the least expensive way to have quality insurance? The service manager goes out to check the job, or the technician completes the paperwork and it gets checked back in the office."
Both methods work as ways to provide quality assurance, said Proctor. Unfortunately, "neither is being done."
There could also be a call-in system, like the ones certain utilities are starting to apply, Proctor said. The technician calls in and gives system measurements (airflow, charge, superheat, subcooling, etc.) to a live person on the phone. If the numbers are problematical, they can discuss possible solutions then and there. This is a good solution for situations where the techs are not comfortable reporting their own errors to supervisors, Proctor said. The length of the average phone call is two minutes.
"There are all kinds of really good reasons to get it right in both new installations and for units already in the field," Proctor said. In California, for instance, Title 24 will go into effect in 2005. This regulation will mandate that all new air conditioning, heat pump, and furnace installations (including replacements) must include a thermostatic expansion valve in the system, or the measurement of airflow and repair of ductwork.
In order to meet Title 24 energy requirements, a homeowner could opt to have new, higher-efficiency windows installed, or a new water heater. But why would the A/C contractor want to give away the work to another trade? Why would the homeowner want to spend more money on another piece of equipment when the money could be spent perfecting the new HVAC system's performance?
Ductwork And The Envelope
"You can't fix what you don't measure," stated Mark Modera. "Most duct systems leak."Modera said he would probably compare duct systems from two parts of the United States: the frost belt (upper Midwest and New England states) and the sunbelt (southeastern and southwestern states).
The frost belt has primarily sheet metal ductwork, Modera said - "100 percent of which leaks."
In the sunbelt, he estimates that 85 percent of the ductwork, which is primarily constructed of flex duct or ductboard, leaks. The greatest energy impact occurs during high-demand conditions.
"Why hook up a high-efficiency system to leaky ductwork?" he questioned. "When you use a variable-speed condenser, for instance, the impact of duct leakage is much, much greater. When there are leaks in ductwork it makes the system work in low-efficiency mode." Homeowners do not get the kinds of energy savings they may have been led to expect. "You should be sealing. And you must measure the airflow before and after sealing," said Modera.
Glenn C. Hourahan is the vice president of Research and Technology for ACCA. He will provide an overview of building envelope elements, envelope purpose, and the benefits of good envelopes. He will provide a simulation showing various energy effects of ceiling, crawlspace, and wall insulation, window types, shading, roof color, and infiltration; and considerations for envelope optimization, new construction, and sealing packages.
The News will be present at the public session and will provide a full report in an upcoming edition.
Publication date: 01/26/2004
