Retrofit Materials
CONSTANT AIRFLOW REGULATORS// American Aldes Ventilation Corp., www.
americanaldes.com
AEROSEAL//Aeroseal LLC,
www.aeroseal.com
Aeroseal
ONGOING TESTING SINCE 2008 DEMONSTRATES THE RETROFIT RESULTED IN A 25 PERCENT REDUCTION IN GAS USE FOR SPACE HEATING.
New Technologies The U.S. Department of Energy (DOE), Wash- ington, D.C., estimates the excessive energy used to compensate for leaky air ducts is costing Americans $5 billion annually. In its 40-plus years of experience in performing building retrofits, SWA has found every cen- tral exhaust ventilation system it has ever evaluated in an existing building performs sub-optimally from an indoor air quality and/or energy-usage standpoint. Carlyle Towers’ ventilation system in-
Sealant particles do not coat the entire inside of the shafts but form a tight seal around individual leaks.
PHOTOS: AEROSEAL LLC AND STEVEN WINTER ASSOCIATES INC.
Constant Airflow Regulators
cludes 25 main vertical shafts with 25 roof- top fans. The property owners observed en- ergy usage for the apartment building was substantially higher than similar buildings in the neighborhood. Measurements taken by SWA prior to the retrofit indicated over- ventilation was occurring on the upper-floor apartments while lower-floor units were un- der-ventilated. This difference ranged from 135 CFM on the ninth floor to less than 10 CFM on the bottom floor. As a result, top-floor res- idents experienced loud, overly powerful ex- haust while those living on the bottom floor found exhaust to be weak and inadequate. SWA engineers recognized the comple-
mentary nature of two new technologies— constant airflow regulators (CARs) and aeroseal duct sealing. With funding from the New York State Energy Research and De- velopment Authority, Albany, SWA was able to evaluate the effectiveness of using the technologies together to improve ventila- tion and energy efficiency at Carlyle Towers. Traditional dampers consist of louvers
Constant airflow regulators are factory calibrated so they open and close as needed to maintain the pre- set balance, no matter the changing environmental conditions.
PHOTO: AMERICAN ALDES VENTILATION CORP. 64 RETROFIT // May-June 2013
that are manually adjusted and balanced at the time of construction. Then, each damper must be manually opened and closed on an ongoing basis to ensure an even flow of air is achieved on all floors of the building. Because the flow through any one grille interacts with the flow through all others, the process can be a long and arduous task; adjusting one grille requires re-measuring and readjusting all other grilles. Proper ad- justments are difficult to attain and seldom accomplished. More importantly, because tall buildings are subject to ever-changing
wind and stack-effect pressures, a system balanced in the summer may not be bal- anced in the winter. CARs precisely regulate airflow across a
wide range of pressures and automatically adjust to compensate for current condi- tions. Once installed, the CAR dampers open and close as needed to maintain a constant preset balance, no matter the changing environmental conditions. Aeroseal is a duct-sealing technology
that works from the inside of the shafts to locate and close any holes or gaps that may exist. Developed by LBNL with funding support from DOE, the Washington-based U.S. Environmental Protection Agency and others, the sealant consists of a nontoxic vinyl acetate polymer. Applied as an aerosol mist, the sealant is blown into the exhaust shafts where it remains suspended until it comes upon a leak. There, the sealant sticks to the edge of the hole and binds with other sealant particles until the hole is completely closed. Laboratory testing shows the sealant lasts at least 10 years, likely the lifetime of the duct system.
Installation To mitigate the substantial ventilation leak- age at Carlyle Towers, CARs were installed behind all the apartments’ kitchen and main exhaust grilles. The CAR dampers were factory calibrated for 30 CFM. Because the air restriction mechanism of the dampers open and close with air pressure, they do not require an external power source to operate and need no manual adjustments to compensate for the variable conditions typically caused by seasonal changes. Because aeroseal technology works from the inside of the shafts, there was no need to tear down walls or other internal struc- tures. Instead, each ventilation shaft was accessed, one at a time, via its termination point where the roof fans are placed. Each roof fan was removed and a thin, flexible tube was connected to the outside en- tranceway of the exposed shaft. The delivery tube runs lengthwise back to the aeroseal
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