TABLE OF CONTENTS This manual presents two methods for calculating cooling loads in nonresidential buildings. The methods presented are based on fundamental heat balance principles and are significantly different from those presented in the previous version of this manual. The methods were developed under ASHRAE Research Project 875. In the work statement that led to the project, "Cooling Load Methodology Development and Load Calculation Manual Update" (875-TRP), Technical Committee 4.1 states: "The current 1997 ASHRAE handbook Fundamentals Chapter 26, includes discussion of four cooling load methodologies (heat balance, weighting factors, CLTD/CLF, and TETD/TA), which is confusing to Handbook users and is undesirable. The heat balance method is the most scientifically rigorous method. The description of this method in the Handbook will be expanded to fully document the procedure."
That statement, although applied to the ASHRAE 1997 Handbook Fundamentals, applies equally to the second edition of the Cooling Load Manual. This manual, Load Calculation Principals, presents the methods developed by RP-875, examples of their use, and the material needed to apply the methods to calculating cooling loads.
When an HVAC system is operating, the rate at which it is removing heat from a space is the instantaneous heat extraction rate for that space. The concept of a design cooling load derives from the need to determine an HVAC system size that, under extreme conditions, will provide some specified condition within a space. The space served by an HVAC system commonly is referred to as a...
