TABLE OF CONTENTS The first step in any load calculation is to establish the design criteria for the project. These data should be listed on standard forms, such as those shown in Figs. 3.1, 3.2, and 3.3, and are needed for either manual or computer calculations.
For manual calculations, some specific times of day must be assumed because it is impractical to calculate manually for every hour of occupancy. Due to solar effects, maximum loads in exterior zones depend on exposure in a typical office building, east-facing zones peak at about 10 a.m. to noon, south-facing at noon to 2 p.m., and west- and north-facing at 3 to 6 p.m., sometimes later. Because solar factors for south-facing glass are greater in winter than in summer, a south-facing space may have a greater peak cooling load in November or December than in June or July, even though the outdoor ambient condition is cooler. Load factors described below must be determined for all these times. In addition to assumed maximum loads, all zones must be calculated for one building peak time, usually 3 p.m. for an office building. Public assembly buildings such as churches and arenas
will usually peak 2 to 3 h into the occupied period. The thermal mass of the building structure creates a load leveling or flywheel effect on the instantaneous load.
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