TABLE OF CONTENTS Because of numerous factors and conditions, the heat transfer process for space heat gains, unlike space heat losses, is not steady state and must be analyzed carefully and accurately in order to calculate the cooling load. For example, the heat storage of the materials of a building structure and interior furniture is an important factor. These surfaces and objects will store the thermal energy, and then they will transfer the heat to the room air when they become warmer than room air. This means the instantaneous heat gain for a given space does not convert immediately to the cooling load. Fig. 7-1 shows the difference between the instantaneous heat gain and instantaneous cooling load due to thermal storage.
Cooling load calculations are based on the fundamental concept of heat balance the calculation of which is difficult and time consuming. There are different methods for calculating cooling load.
Transfer Function Method (TFM). Total Equivalent Temperature Differential and system of Time Averaging (TETD/TA).
In this book we will discuss only the Cooling Load Temperature Differences, Solar Cooling Load, and Cooling Load Factors (CLTD/SCL/CLF) procedure. For details of the other procedures, the reader can refer to the ASHRAE Fundamentals Handbook. The Transfer Function Method (TFM) is an approximation of the heat balance method. The CLTD/SCL/CLF method is a simplified version of the TFM which applies to the certain types of buildings for...
