MIL-HDBK-1011/2
4.3.4.2
Ground Reflectance.
Table 1
Natural ground covers tend to be less
Reflectance Values of
reflective than bare soil or manmade
Various Ground Covers
+))))))))))))))))))))))))))))))))))),
surfaces, (Table 1) thereby reducing
*
*
ground-reflected radiation.
* Material
Reflectance (%) *
Ground-reflected light represents 10
*
*
to 15 percent of the total solar
* Light sand dunes
*
radiation transmitted to the first
30-60
* Soil, sandy
*
floor of a building on the sunlit
15-40
* Soil, dark cultivated
*
side and may account for greater than
7-10
* Green grass, meadow
*
50 percent of total radiation
20-30
* Dry grass
*
transmitted on the shaded side.
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* Woods, bushes
*
5-20
* Bark
*
Some portions of this
23-48
* Water surfaces, sea
*
radiation can provide desirable
3-10
* Concrete
*
daylighting within the building, but
30-50
* Brick, various colors
*
glare and total solar gain are
23-48
* Blacktop
*
usually greater problems in hot
10-15
*
*
climates.
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In general, trees and shrubs and other irregular, vegetation have
lower reflectivity than planar vegetated surfaces such as grass.
4.3.5
Other Considerations
4.3.5.1
Reducing Airborne Dust. Vegetation filters the air and minimizes
lifting of dust from the ground. It is most useful on the windward side of
buildings especially when highways, open lots, or parking lots are located
nearby.
Reducing Sound Levels. Mixtures of deciduous plants and evergreens
4.3.5.2
reduce sound more effectively than deciduous plantings alone; however,
vegetation has a relatively small effect on sound levels.
4.3.5.3
Visual Screening. Vegetation can also be planned to provide visual
screening for privacy requirements as long as it does not interfere with the
design for effective ventilation.
4.4
Building Form
4.4.1
General Principles. Building orientation will determine the
intensity of solar radiation falling on the walls and roof of the building,
and the ventilative effectiveness of the building openings. Building shape
determines the amount of exterior surface area for a given enclosed volume and
the length of the interior path of the ventilation air. Together, these
factors determine the relative amount of thermal transfer through the building
envelope and the potential effectiveness of a design to provide cooling by
natural ventilation.
Although building shape and orientation are important in minimizing
unwanted solar gain, it is possible to counteract some of this gain or
partially compensate for improper orientation and shape with the design of the
building envelope. Such design measures include light-colored wall surfaces,
locally shaded windows, extra insulation, wingwalls, etc. Likewise, it may be
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