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41 <br />Variable Air Volume A S stem <br />A variable air volume system is an HVAC system that, like the multi-zone system, distributes <br />conditioned air from a central location to each space according to the amount of cooling or <br />heating necessary to each space. A central air-handling unit would provide primarily cold air <br />through ductwork for cooling and dehumidification purposes, while duct-mounted hot water <br />coils at each conditioned space provide heating. <br />Advantages <br />• Over 20 year median useful life <br />• Low maintenance cost <br />• Low energy cost <br />• Good control over indoor air quality with outside air ventilation control and high filtration <br />efficiency <br />• Good control over space temperature and humidity levels <br />• Quiet operation <br />• Remote access available for control and troubleshooting <br />• Can connect with other centralized digital controls <br />• Systems may be readily modified to accommodate revised space configurations and <br />usage <br />Disadvantages <br />• Highest installed cost <br />Like the multi-zone, a variation would be the installation of packaged rooftop source <br />equipment in a variable air volume configuration. Self-contained DX equipment would <br />replace the water chiller and pumps and a gas furnace would replace the boiler as source <br />equipment. This would reduce the installed cost but would result in a shorter median life of <br />15 years and higher energy usage and cost. <br />The following is an illustration of a typical VAV system: <br />VAV Ttu~nlnd with <br />A~ VWITrnMW•rA1W~ 81s: 0.00 <br />App1IC~tl0~k VAV Oa wV Ilpt YM1M RMrM .TYP~~ Of: t <br />. N~ <br />MNIR <br />F1WIE <br />TJ'p• T~q <br />~ ~ ~ 8p~o~ T~~rr N <br />S~AF1~~ M <br />IpOht CnuekY 01 <br />(41) <br />