Agenda - Planning Commission - 06/03/2010

Home

The important message is that solar building design can not be achieved simply. through "add-ons."The approach discussed above is integral to the building and needs to be considered in the predesign stage,. whether for new construction or renovation. DireR WIn m~=o~o~ L~ nationwide. Even within a given geo- graphicarea, microclimatevariations must betaken into account. Design tools such as ENERGY-io and Energy Plus contain the weather data files for numerous U.S. locations). Sunspaces ELEMENTS OFSOLAR BUILDING DESIGN Before we see how these ideas can be en- couragedthrough land-use regulations, it is necessary to understand how to incorporate solar concepts into buildings. Keep in mind throughout the folldwing discussion that solar design islocation-specific. We'll begin with basic solar building design concepts and techhologies. Latitude. Depending on location, the height and angle of the sun in the sky (the azimuth) throughout the year and climate characteristics (for example, heating and cooling degree days and air-flow patterns) will establish the basis forthe design of solar buildings and therefore, solar access requirements. (Specific climate data are available-for numerous weatherstations Thermal Gtorag< Wall WuM1esyoPoOE/N0.0.and Ne SUSpinable [lulltlingz lntlustdes [ouncll Energy-efficiencymeasures. These measures include proper levels of insula- tionand glazingtype, control of air infiltra- tion, prgperly sized mechanical equipment, efficient appliances and office equipment, and electric lightingsystems and controls. DayGghting. This refers to the use of solar radiation captured through the use of clerestory glazing, saw[ooth roof moni- tors,light shelves (horizontal sufiaces over the wihdows' exterior that reflect daylight onto the ceiling and deep intothe building), lighttubes,andothermeansofbringing fight into the building. Studies have shown thatdaylight can reduce electdc bills 3o to 5o percent. Skylights are commonly used for daylighting. However, unless they are designed as an integral part ofthe building, they will likely increase the cooling load. Elec- triclighting controls are integral to the use of daylighting so that light levels are constant when people are present and fixtures are not on when radiation levels are adequate. Suntempering. For housing and small nonresidential buildings, suntempering may be a desirable approach. Suntempering is accomplished by simply moving more ofthe. windows to the south and relying on interior finishes and furnishings forthermal or heat storage. However, suhtempered buildings will not reduce the use of purchased energy to the degree that solar buildings will. Passive solar or whole building design. Passive solar is the building itself. A passive solar building makes use ofthe building's nonmechanical elements and properori- entation to provide daylighting; to collect, store, and distribute solar energy; and to take advantage of natural cooling. These buildings have thermal mass to store and emit heat during times when it is needed and to lessen the need for air conditioning. The amount ofthermal storage required is dependent on the area ofsouth-facing glass. Care must be taken in selecting glaz- i ng sothat the solar gains from the southern orientation are maximized: These buildings also employ meansto direct natural airflows (solar-drive convective air movement) into the building using such strategies as oper- ablewindows, vents at floor level, and wing walls (walls that project from.the building) Iobringairintothebuilding.Additional ventilation is provided by whole-house fans and operable clerestory or cupola windows. - Passive solar buildings may also use night radiation to Flush excess heat. This method involves exposing masonry surfaces to the cool night sky and insulating these surfaces ZONINGPRACTICE y.to AMERICAN PIANNING /550[WnON Ipage3/'}