>Cooling Load

Household Appliances

Appliance loads are concentrated mainly in the kitchen and laundry areas. Based on contemporary living conditions in single-family houses, a sensible load of 470 W should be divided between the kitchen and /or laundry and the adjoining room or rooms. For multifamily units, the sensible heat gain values should be about 350 W. these values assume that the cooking range and clothes dryer are vented.

Lighting

Since lighting is often the major space load component, an accurate estimate of the space heat gain it imposes is needed. Calculation of this load component is not straightforward; the rate of heat gain at any given moment can be quite different from the heat equivalent of power supplied instantaneously to those lights. Only part of the energy from lights is in the form of convective heat, which is picked up instantaneously by the air-conditioning apparatus. The remaining portion is in the form of radiation, which affects the conditioned space only after having been absorbed and re-released by walls, floor, furniture, etc. this absorbed energy contributes to space cooling load only after a time lag, with some part of such energy still present and reradiating after the lights have been switched off.       There is always significant delay between the time of switching lights on and a point of equilibrium where reradiated light energy equals that being instantaneously stored. Time lag effect must be considered when calculating cooling load, since load felt by the space can be considerably lower than the instantaneous heat gain being generated, and peak load for the space may be affected significantly.

Computers

Computer rooms housing mainframe or minicomputer equipment must be considered individually. Computer manufacturers have data pertaining to various individual components. Heat gain rates from digital computer equipment range from 240 to 550 W/m2. While the trend in hardware development is toward less heat release on a component basis, the associated miniaturization tends to offset such unitary reduction by a higher concentration of equipment.

Others

Further allowances should be considered when other equipment is present. Environment variations can also have an effect on the heat gain from appliances, primarily with regard to the percent of heat gain that is radiative versus convective.