August/September 1979 RAIN Page 13 A better waY' townhouse adaptation for passive solar heating where cement-bloch common walls provide tbermal mass, sound insulation and fire safety. Tbis system requires about Olle-half the nm~ greenhouse area and half the tbermal mass as a passive single-jil1nily home in the same climate. ~_ l lIl ~" ,,'r-i Developers: Environmental Community Housing .1 n,j:.~ Organization. Architects: Van del' Ryn, Caltborpe IMr-'" and Ptrs. 1 Solar Suburbia SOLAR 'i'IUTIES ROADS rESIDENTiAl 500 PftAWl 9OL.A.R TO'NN SOLAR Sl'RAWI. ~ousc TOWN HOuSE PMENT COSTS PER UNIT 400 300 200 TRANSPORT ~nON '00 SOl..).A TOWN SO~R SPRA'M.. HOUSE TOWN HOuSE and low-density models is nearly 100 perccnt (Fig. 2). In all the issues contrasted, high-density planned developments had a more benign environmental impact than low density sprawl. Let us assume that a solar installation, either passive or active, can reduce the energy consumption of each dwelling for heating, cooling, and hot water by 50 percent on a national average. (Although solar can provide up to 70 percent of a building's needs, the cost effectiveness of such high performance systems falls off radically.) This 50 percent reduction would produce a new graph (Fig. 2) in which the average energy consumption for each solar single-family dwelling would still exceed the consumption of the nonsolar climatically unresponsive higher density planned dwelling by 30 percent! This solar application would not significantly affect the water and pollution, transit, or land use comparisons. It would, however, raise the capital costs for the low-density model significantly, fueling the argument that only a financial dite can afford such an environmentaHy responsive future. A more concrete example of these issues is given by a welldesigned passive solar home located on the tOP of the highest ridge in the California Coastal mountain range. Just down the ridge is another house under construction of a more standard variety. Comparison of the energy and environmental impacts of the two houses shows that the real differences are small. Both consume bcautiful open space located near metropolitan arcas which should be preserved for public usc. They will probably produce the same amount of solid waste and consume the same amount of materials and energy in construction . Both demand an equally irresponsible infrastructure cost in roads and utilities. Finally, in gross energy terms the annual energy consumed commuting to town far outweighs the energy saved by the solar system. A 70 percent solar contribution for a well-insulated house in this climate will provide around 21 million BTU (MBtu) per year. Assuming 15 miles per gallon, a round trip to the town located 30 miles away will consume .52MBtu. This means that 260 commute days per year, excluding shopping, school, and other trips, will consume 135 MBtu or 6-112 times the energy provided by the solar system. And commuting represents only 45 percent of the avcrage family's mileage. Clearly, a comprehensive energy analysis of dcvelopmcnt patterns shifts attention from energy technologies to patterns bascd on social and economic structures. Transit Transportation is the largest nonindustrial energy consumer we have, accounting for 25 percent of the national energy consumption. In this realm, as is so often stated for solar design; conservation should precede the implementation of alternativc fuel sources. The simplest technique for reducing transportation is to minimi,-e the distances between home and work, home and commerce, home and school. The reduction of the national average of 13,000 miles traveled per capita would not only be environmemally responsible but perhaps would provide a higher quality of life. The typical family living outside the city limits travels 23 percent more miles or approximately 35M Btu more per year than the city dweller. This amount of energy would heat an avcrage low-rise condominium in town for one year. The overall densities, the pattern of daily activities, and the alternate transit systems available are the issucs critical to reducing total auto miles traveled for individuals. Distribution of employment sites (decentralizing downtown employment concentrations), decentralization of commercial site location (presence of local neighborhood storcs and services), and transit networks (buses, trains, trolleys, bicycles, pedestrian paths) become the significant variables. These concerns in turn can help recreate the kind of human scale urban amenities, such as cafcs, neighborhood parks, and local shops, which make higher density communities desirable. Form, density, and scale Beyond the implications of density, scale, and pattern on transit are some simple thermodynamic laws relating building form to energy consumption. The question of optimum building massing, size, and orientation is a complex field and is extremely case spccific with respect to climate and building use. However, it has consistently been shown that row houses and walk-up apartments are more energy efficient than single-family dwellings or highrise apartment buildings. The old row house with proper orientation, massing, and its common walls can achieve thermodynamic results similar to those of underground houses which have become a symbol of energy-conserving, extremely well-insulated, environmentally responsive design. The potential energy demand of a multiple-family dwelling can be one-h~lf that of a single
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