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8 <br />ranges that are comfortable for most people engaged in largely sedentary activities. The <br />ASHRAE standard assumes "normal" indoor clothing. <br />Uniformity of temperature is important to comfort. When the heating and cooling needs of a room <br />within a single zone change at different rates, rooms that are served by a single therrnostat may <br />be at different temperatures. Humidity is a factor in thermal comfort. Raising relative humidity <br />reduces the ability to lose heat through perspiration and evaporation, so that the effect is similar <br />to raising the temperature. Humidity extremes can also create other IAQ problems. Excessively . <br />high or low relative humidities cam produce discomfort, while high relative humidities can promote <br />the growth of mold and mildew. <br />Ventilation fo Meef Occupant Needs <br />Most air handling units distribute a blend of outdoor air and recirculated indoor air. HVAC- designs <br />may also include units that introduce 100% outdoor air or that simply transfer air within the <br />building. Thermal comfort and ventilation needs are met by supplying "conditioned" air (a blend of <br />outdoor and recirculated air that has been filtered, heated or cooled, and sometimes humidified or <br />dehumidified). <br />The amount of outdoor air considered adequate for proper ventilation has varied substantially <br />over time. Tha current guideline issued by ASHRAE is ASHRAt; Standard 62-1989. (ASHRAE <br />committees are currently discussing and debating a revision to the 62 standard.) The building <br />code that was in force when your buildings HVAC system was designed may well have <br />established a lower amount of ventilation (in cubic feet of outdoor air per minute per person) than <br />is currently recommended. ~ - <br />A copy of the Executive Summary of the Robson and Woese HVAC System Life Cycle Analysis <br />for Whiffed and Northern Buildings follows. <br />The following appendices have also been included to provide additional background information <br />about HVAC system design and selection: <br />o HVAC Systems: How They Work <br />o Choosing the Best HVAC System <br />We will be pleased to provide additional information or details upon request. <br />s htto:Nwww.bagl.com/index.htm <br />8 Prepared: 05/03/2001 <br />C:\My Documents\Abstracts2001\06-0~01\FiVACIntroAtt0605.doc Printed: 05/31/2001 <br />