Article Figures & Data
Figures
- Figure 1.
Solar path diagrams for three latitudes that range from southern United States and northern Mexico (32°) to northern United States and southern Canada (48°). The horizontal axis shows true azimuth angles measured from south. Solar paths are plotted on the 21st of each month. (Adapted from Mazria and Winitsky (32)).
- Figure 2.
Average relative windspeed (compared to wind in the open) as affected by shellerbelts of different density (38). Distance from the windbreak is measured in units of windbreak height, H.
- Figure 3.
Density of crowns of leafless trees of three species as determined from 35-mm slides (from 51).
- Figure 4.
Approximate average fractional reductions in solar radiation on vertical surfaces in the shade of dense, midsize trees such as Norway and sugar maple.
- Figure 5.
Patterns of tree shade at 40° latitude (about Columbus, Ohio and Denver, Colorado). Even deciduous trees may reduce solar heat input in winter.
- Figure 6.
Patterns of tree shade in midwinter (Jan. 21) at 30° (New Orleans) and 48° latitude (Grand Forks, N.D.) with tree 19 feet farther south of the house than in Figure 5. The tree in this position would not shade the house from April through August at either latitude.
- Figure 7.
Optimum landscape concept for a temperate climate with winter wind predominantly from the west and northwest.
Tables
- Table 1.
Approximate number of Btu through 1 square foot of single-pane window on a clear day for windows facing different directions at three latitudes (January 21 and July 21 are representative of winter and summer).
Direction window faces 32° Latitude (e.g.,El Paxo, TX) 40° Latitude (e.g.,Columbus, OH) 48° Latitude (e.g.,Spokane, WA) Jan. 21 July 27 Jan. 21 July 27 Jan. 21 July 27 North 160 460 120 450 90 450 East/west 650 1,150 510 1,190 360 1,230 South 1,710 500 1,630 700 1,400 950 - Table 2.
Reported energy savings by windbreaks, in percent of heat used by an unprotected house.
Model buildings in N.D. (3) 23-40 Models in wind tunnelst In Kans. (55) 15 In N.J. (20) 9 Individual unoccupied mobile home in Pa. (12) 12 Occupied full-scale houses Townhouse in N.J. (31) 3 Detached house in N.J. (15) 10 Detached houses in Radisson, N.Y. (42) 25 Windbreak around mobile home park in Pa. (54) NM* ↵* NM = not measurable
- Table 3.
Reported energy savings from shade of trees in summer, as percent of air conditioning energy use by an unshaded house.
% Computer modeling Heavy shade on all walls and roof of a concrete block house in Fla. (5) 19 "Optimally landscaped" trailer on July 23 in Ga. (4) 52 Shade of mature tree canopy on small test house in Davis, Calif. (33) 10-40 Shade on N, E, and W sides of wellinsulated house in Chesapeake, Va. (8) 11 Measured in mobile homes Dense shade by a deciduous grove in Pa. (13) 75 Landscape trees in Fla. (41) 40 Partial tree shade in Ala. (30) 59 Shaded conventional houses in Tex. (44)a 11-24 ↵a I made the assumption that winter electricity bills represented energy use for purposes other than space conditioning
- Table 4.
Reported reductions in interior air temperatures (°F) of houses or model houses by complete tree shade.
One-eighth scale model house with realistic insulation and thermal mass but not ventilated in Utah (36) 13 Lived-in houses surveyed in Calif. Central Valley (7) Insulated 2 Not Insulated 6 Wood-frame trailer, uninsulated, not ventilated, tree shade in Calif. 20 - Table 5.
All-year effects of trees on energy use for heating and cooling. Energy use is for houses with vegetation compared to the same house in a large open space.
Study HDD-CDDa Energy useb % Measured in mobile home In deciduous woodlot in central Pa. (13) +5280 −24 – Computer modeling results Heavy deciduous shade on one-story frame house in Orlando, Fla. (5) −2490 −15 −128 Row of trees 15 feet to south in Calif. (48) Conventional house Palm Springs −2440 −7 −60 Truckee +8170 +4 +38 Solar house Palm Springs −2440 +1 +5 Truckee +8170 +25 +88
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