Using measured equipment load profiles to 'right-size' HVACsystems and reduce energy use in laboratory buildings (Pt. 2) Page: 6 of 14
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Design Loads vs. Measured Power
3L2A 3L2B 3L2C 3L2D 3L2E 3L2H 3L2L
U Design Load * MaxApparent Power * Max Interval Power
Figure 3 Comparison of equipment power used for design, measured peak apparent (instantaneous) power
and maximum interval power for various laboratory spaces in UC Davis.
2.3 Benefits of Right-sizing
A study by Enermodal and NREL  demonstrates the influence of the design assumption for
plug loads on the sizing of mechanical equipment. The analysis was conducted on a prototypical
100,000 sf laboratory building, in different climatic zones. The minimum ventilation rate for the
building was 1 cfm/sf. The base case equipment load was 12 W/sf, which corresponds to an
"over-size" load, and parametric cases were modeled with "right-sized" loads of 8 W/sf and 4
W/sf. Figure 4 illustrates the reduction in total chiller tonnage from rightsizing. For example, in
Atlanta the assumption of 8W/sf results in a reduction of 100 tons of cooling, while the
assumption of 4 W/sf results in a reduction of about 200 tons. The analysis by Martin 
computed the cost of over-sizing HVAC and piped utilities in laboratory projects to be at least
$7.50/sf, and more likely to be 2 or 3 times that, depending on the extent of over-sizing.
Figure 4. Reduction in chiller tonnage due to rightsizing equipment load down from 12 W/sf to 8W/sf and
4 W/sf for different climatic contexts. Based on parametric simulation study of a prototypical 100,000 sf
laboratory building [Enermodal and NREL 2003].
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Mathew, Paul; Greenberg, Steve; Frenze, David; Morehead, Michael; Sartor, Dale & Starr, William. Using measured equipment load profiles to 'right-size' HVACsystems and reduce energy use in laboratory buildings (Pt. 2), article, June 29, 2005; Berkeley, California. (https://digital.library.unt.edu/ark:/67531/metadc901308/m1/6/: accessed May 23, 2019), University of North Texas Libraries, Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.