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from outside air during the day. As daytime <br />temperatures rise, the cooler surface acts as <br />a heat sink for the living space. <br />An ideal design will orient the major <br />work, study, and living areas to the south and <br />minimize the east-and west-facing glass. <br />Even the type ofglazing selected for each <br />orientation may differ so thatsolargainsfor <br />south-facingglass are maximized and those <br />for east- and west-facing glass are minimized. <br />Passive solar buildings draw upon <br />at least orie ofthree design strategies to <br />provide heat: direct gain, sunspaces, and <br />thermal storage-orTrombe-walls. Trombe <br />walls are glazed, south-facing masonry or <br />concrete walls with a selective surface that <br />aids in collecting and storingthe solar ra- <br />diation. Athermalstorage system is often <br />referzed to as an indirect system. <br />Passive solar buildings depend on <br />properglazing-to-storage ratios and prop- <br />erlysized overhangs to avoid overheating <br />in spring and fall. Because these buildings <br />use normal building components to meet <br />muchoftheirheatingandcoolingneeds, <br />they require little maintenance. In some <br />climates, a passive solar home orsmallnon- <br />residentialbuilding (e.g., a school or office <br />building) may not require a central heating <br />and tooting system-a major cost saving - <br />benefit-and those that do require auxiliary <br />heating and coolirig will use smaller systems <br />than conventional buildings. <br />Buildings of io,ooo square feet. or <br />smaller make up the majority ofthe non- <br />residentiatsector. Contrary to popular <br />perceptions, smaller commercial, institu- <br />tional,and industrial buildings are similar <br />78 <br />Passive solar <br />buildings draw upon <br />at least one of three <br />design strategies to <br />provide heat: direct <br />gain, sunspaces, and <br />thermal storage. <br />to residential buildings in that they do <br />require heating as well as daylighting, cool- <br />ing,and ventilation: For larger buildings, <br />daylighting is especially important since <br />lighting is sometimes the biggest user of <br />energy. Many buildings, regardless of size, <br />can benefit from using solarto heat and to <br />preheat ventilation air. <br />Active solarsystems. This refers to the <br />use of collectors, usually located on the <br />roof to collect solar radiation to heat water <br />fordomestic uses and possibly, to provide <br />auxiliary heating in the winter months.The <br />systems that provide both hotwaterand <br />heat are often referred to as combisystems. <br />Some collectors for hot water systems are <br />freestanding, especially when roof orienta- <br />tion isnot ideal. Fdrthese systems greater <br />solar access is necessarythan required for <br />passive solar buildings since the collectors <br />are likely to be placed at ground level. Ha- <br />waiinow requires that all new homes install <br />solar hot water systems. <br />Photovoltaic (Ply rystems. PV systems <br />generate electricity. The PV system might <br />6e on the building's roof, integrated into _ <br />its overhangs, or provide the skin forthe <br />building's facade or atrium. Distributed <br />power is a term likely to become part of <br />our future vocabulary. Distributed power <br />is PV-generated powerthat is fed into the <br />utility's grid. In time, if enough buildings <br />generate more powerthan they need, we <br />will have less need for additional power <br />plants. <br />ventilation air. For nonresidential build- <br />ingslike institutions, industrial facilities, <br />and warehouses; transpired air collectors <br />placed on the south side of buildings have <br />proven to be an effective technique topre- <br />heatventilation air. Tanspired collectors are <br />adark-colored, perforated facade with a fan, <br />or the building's existi ng ventilation system <br />drawsairintothebuilding.Theairspace <br />between the absorber and the huilding wall <br />form a plenum. The solar energy absorbed <br />by the dark absorber and transferred to the <br />airflowingthough it can preheat intake air <br />by as much as qo°F. The absorbers can be <br />added to or designed as part of the build- <br />ing's facade. Because of fire code require- <br />ments, they may not be appropriate for <br />some multistory buildings. <br />Evaporative cooling. This refers to <br />the use of a water medium to cool airfor <br />climate control in dry climates. Not all cli- <br />mates require compressors to cool air and <br />ZONINGPRACTICE y.ao <br />PMERICAN PIFNNINGAGGGCIATION ~0°9e 4 <br />