Page 81 - Zero Net Energy Case Study Buildings-Volume 1

sive means are not sufficient. Air is drawn up and out mechanically through the same chimney air outlet. These air handling units also operate at night during the cooling season if directed by the building management system (BMS) to “night purge” with cool night air so that the building is pre- cooled for the following day’s operation. The night purge operation shifts peak electric demand to less expensive hours of operation and reduces the necessary capacity of the heat pump system.
The laboratory wing is served by a low-pressure-drop air system for cooling. The unit is sized for low air velocity, reducing fan and motor sizes. The radiant floor heating system is used in the laboratory wing as well. Laboratory fume hoods are located in an isolated room so that the laboratory space can utilize openable windows and natural ventilation as the occupants desire. Since this water quality laboratory has no unusual safety issues, as is sometimes the case in laboratory environments, the client schedules the mechanical ventilation to be shut down at night to eliminate unnecessary energy use. There is, as a result, no night purging operation for this building wing.
Plug Loads
As in most low-energy buildings, plug loads account for a large portion of the total energy used. Plug loads used in the energy modeling are based on available public information for office space, equipment lists and inventories from the client for the laboratory and other program spe- cific spaces. Use patterns in the modeling were also built up from observation and experience on previous projects. With metering for individual circuits in place, actual measurements show how much actual plug load energy use has deviated from these modeling assumptions.
WATSONVILLE WATER RESOURCES CENTER
CASE STUDY NO. 4
Zero Net Energy Case Study Buildings: Volume 1 6
PHOTO: BRUCE DAMONTE
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