Page 35 - Zero Net Energy Case Study Buildings-Volume 3

THE J. CRAIG VENTER INSTITUTE
CASE STUDY NO. 12
Plug Loads and Equipment
Since plug loads generally account for the largest amount of energy consumed in ZNE buildings, the design team wanted to understand what the energy consumption profiles were for typical laboratory equipment. These profiles typically do not correlate with the equipment rating, so the they had to measure the individual items in existing lab conditions and create an inventory with the measured energy profiles. This was important in order to model the building sufficiently well to estimate the size of the solar array.
Still, the equipment load could only be an estimate in a research laboratory, where the research projects are not well known in advance and where purchase is often based on cost.
A special effort was made with the laboratory [-80°C]-freezers2, which typically are located in the lab support space of each researcher and are electric-powered. As a result, heat put out by the freezers contributes to the cooling load of the space. The design team proposed an idea that would significantly reduce the energy demand of this method of providing freezer space in the lab: use water-cooled freezers, which are much more efficient, and put them all in one room. As such, researchers could share space in the freezers, thereby reducing the number of freezers that would be used. Sharing freezers that were centrally located required a change in the re- search culture, but the scientists accepted the idea, and the equipment energy use was sizably reduced.
A system of color-coded electric outlets in the laboratories identified those that would shut off at night, so non-critical equipment could be plugged into them. (See photo below.)
2 The laboratory uses both [-80°C]-freezers and [-20°C]-freezers, but since the [-80°C]-freezers use the most energy, they were specified as water-cooled and centralized in the lab.
(Above) Water-cooled [-80°C]- freezers are more energy efficient and are shared by researchers in a centrally located Freezer Room. (Cour- tesy of ZGF Architects)
Zero Net Energy Case Study Buildings, Volume 3
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