Heating and Cooling Energy - Hydrogen and Fuel Cells: Advances in Transportation and Power - page 246

possible. Most inlets or hoods shared fans, so it was not possible to switch
off a fan if any inlet was in use. The exhaust air volume was about the
same as the minimum supply air. The floors are open spaces so the air
moving around the floor was transferred from one floor to the other by
pressure differences. Although there was a minimum outside air setting
in the packaged units, outside air had to make up the exhaust by supply
air from the packaged units and infiltration. The work schedule was flex-
ible, so although the building operated on a one-shift schedule, workers
could be in the building working any time of the day. The exhaust system
ran constantly and due to exhaust, the HVAC systems had to operate the
same way all the time.
The building had operated this way by for many years. During 2000-
2001, the power rate increased dramatically due to the energy crisis on the
West Coast and it became a high priority to reduce the power usage.
Since there were no dampers in most of the exhaust inlets and no
automatic controls on the fans the exhaust air was very high and unneces-
sary. Modifications included easier operating dampers, using magnets to
hold the dampers open and relocating the dampers so they would not ob-
struct normal operation. Visible warning lights were installed to indicate
if the associated exhaust fans were on or off. The fans were controlled by
variable frequency drives (VFD). The building had a direct digital control
(DDC) system, so the VFDs were linked into the DDC system to schedule
and monitor their operation. Workers were able to close dampers and turn
off fans when they were not needed. The DDC system monitored the VFD
operation and when the building was unoccupied, the VFDs were set to
run at minimum. The building achieved a 30% energy reduction during
occupied hours and 60% during unoccupied hours. Environmental safety
standards were used to check if the exhaust amounts were adequate.
References
Barker, Jennifer, “Hoops and Hurdles,” Home Power , Issue #80, December 2000/January
2001, pp. 64-65.
Boyle, Godrey, Editor, Renewable Energy Power for a Sustainable Future , Oxford, England: Ox-
ford University Press, 1996.
Davlin, Tom, “PLCs Upgrade Power Plant Control System,” Intech , Volume 40 No 10, Octo-
ber 1993, pp. 38-39.
Hordeski, Michael F., New Technologies for Energy Efficiency , The Fairmont Press: Lilburn, GA,
2003.
Khan, Khalid, “Mass Spectrometers, Poll Plant Pollution,” Intech , Volume 40 No. 10, October
1993, pp. 40-42.
Scientific Staff of the Massachusetts Audubon Society, The Energy Saver's Handbook , Emmaus,
PA: Rodale Press, 1982.