Page 64 - Zero Net Energy Case Study Buildings-Volume 1

CASE STUDY NO. 3
IDeAs OFFICE BUILDING
When full heating or cooling mode is required, however, the heat pump operates to provide the appropriate water temperature in the radiant system and the supply fan operates at a fixed speed to provide the fresh outdoor air. Building occupants normally operate the windows to close under these conditions. The fan is designed only to provide fresh air since the heating and cooling is done via the radiant slab and it was originally designed to operate whenever the heat pump was activated. This type of operation, while workable in practice, resulted in some energy use inef- ficiency, which is discussed below.
There are separate ventilation fans provided for toilet room exhaust and the server room. By design, the server room does not have a separate cooling system, which generally requires a continuous power supply. The server room was located specifically on the north side of the building with the least external load amount and night purging is used to cool the room down at night. With minimal external loads, the server room normally floats through the following warm day without excessive interior temperatures. In addition, the server room itself is programmed for a higher temperature than normal for such spaces. Note: the servers are reported to have functioned well for the past five years without apparent ill effects on the equipment.
Electrical Plug Loads
Plug strips at each workstation are identified as either controlled electrical outlets or fixed outlets. The controlled outlets have built-in occupancy sensors to manage equipment that can be turned off when not in use. Fixed outlets remain at full power availability at all times. These are required for computer CPU’s but the flat screen monitors can be plugged into the controlled outlet. (The staff choose to plug cell phones into the fixed outlet so that charging is not interrupted.)
In 2007, each engineer’s workstation included one high efficiency flat screen monitor with a typical CPU box on the floor. Since then, for productivity purposes about half of the staff have
48
Zero Net Energy Case Study Buildings: Volume 1
PHOTO: DAVID WAKELY