TABLE OF CONTENTS Current practice is to use computers for load calculations. Many load calculation programs exist, with varying degrees of complexity and accuracy. Most can be run on small personal computers while some require large computer systems. There are several important things to consider when a computer is used:
1. The program to be used must be credible and well documented. Any automated procedure should be capable of being supported in a legal review or challenge.
2. The input must be carefully checked for accuracy. This is not a simple task since the complete input can be voluminous and complex. In fact, it often takes at least as long to properly input and check the data as it does to manually calculate the loads.
3. The output must be checked for reasonableness. Many people look on a computer printout as perfect and final. This is seldom true in HVAC work. The old rule of garbage in, garbage out (GIGO) is never more applicable than in HVAC calculations.
4. Different load calculation programs may yield different results for the same input data. In part, this is due to the way the programs handle solar effect and building dynamics. The differences may be significant. When using a new program, the designer is advised to manually spot-check the results.
There are also many computer programs for estimating energy consumption. Many include subroutines for calculating heating and cooling loads. These calculations are seldom suitable for design, because they tend to be...
