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A SHRAE Technical Committee 4. l, Load Calculation Methods, has completed two recent research projects and the results will be of interest to engineers who perform cooling load calculations. ASHRAE Research Project RP-822 focused on development of a method by which the actual heat gain and radiant and connective split from equipment in buildings could be measured [Hosni et al.,1996]. This methodology then was incorporated into a second research project, RP-1055, where the technique was applied to a wide range of equipment [Hosni et al.,1999]. A research team at Kansas State University, led by M.H. Hosni, completed both of these research projects. This research was followed up independent research by Wilkins and McGaffin,1994.
The independent research by Wilkins and McGaffin produced significant data on the overall building load as measured at panels serving distinct areas within a building. Data was also collected on the measured power consumption of individual items of office equipment. The TC 4.1 research as executed by Hosni et al., expanded on this by obtaining data in a more controlled and formal manner.
Hosni's work for TC 4.1 also included measurement of the radiant and convective split of the heat gain from the equipment. Documentation relative to radiant and convective split is relevant when using advanced load methods.
Research Project RP-1055 obtained heat gain measurements from office, laboratory, and hospital equipment. The final effort of this research was to take the collected data and identify patterns or generalizations that could be widely used for common applications. It was discovered that results for general office equipment could be generalized, but results from laboratory and hospital equipment proved too diverse.
Here we will present generalized guidelines based on the results of all previously mentioned research for office equipment. The reader is encouraged to consult the project's final report and the technical paper (Hosni et al., 1999) for detailed discussions of results for laboratory and hospital equipment.
Nameplate vs. Measured
It is now well documented that nameplate data overstates the actual power consumption of office equipment. Power consumption of this type of equipment is assumed to be equal to the total (radiant plus connective) heat gain. Many engineers would find it convenient if a standard number or ratio could be applied to all nameplate data...