The present American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) standard 62-1981 "Ventilation for Acceptable Indoor Air Quality" is being revised. The recommended ventilation rate will be increased four-fold from 2.5 I/s/person to 10.0 I/s/person. The immediate response to this proposal is that the energy consumption and costs will parallel this increase and rise dramatically. It is the intent of this paper to provide a better understanding of the actual effect of the changes to the ASHRAE standard. The Introduction describes the reasoning behind the proposed changes to the ASHRAE standard and the method by which the authors have evaluated the effects of the changes. Part 1 presents the Building Simulation Data and the design parameters used to analyze the effect of the proposed increase in the minimum outside air ventilation rate. These include the building construction, building air systems, weather data, building simulation program background and calculation methods. Part 2 explains the results obtained from performing an analysis for each building system by increasing the minimum outside air ventilation rate 4-fold from 2.5 I/s/person to I 01/s/person. The interpretation pays particular attention to the effect economizers have on the energy consumption of building air systems. This issue provides a key to the understanding of the whole ventilation issue. Part 3 discusses the results, the factors which affect the results and explains the eff ect economizers have on the ventilation system and the energy consumed.