MIL-HDBK-1003/19
as adjustable shades and shutters that shield the solar aperture from direct
and diffuse sunlight during the cooling season is essential. The term
defensive cooling refers to strategies or devices that prevent excess heat
from entering a building, in contrast to procedures for removing such heat
with air conditioning equipment after it has gained entry. Because of the
high SHFs obtainable in the mild region, conservation measures are not as
important as in regions further north.
4.2.2.2 Moderate climates. The moderate region includes most of
California, the southern half of Nevada, the central third of Arizona, and
most of New Mexico, Texas, Louisiana, Mississippi, Alabama, Georgia, and
South Carolina. The Florida panhandle and most of the North Carolina coast
are also included.
Thermal storage walls, sunspaces, thermosiphoning air panels, and direct
gain systems are all appropriate in this region. The solar apertures will
be larger than in the mild region and more thermal insulation will be
required. Defensive cooling strategies are also important to overall
performance.
4.2.2.3 Harsh climates. The harsh region includes most of Washington,
Oregon, Idaho, Nevada, Wyoming, Utah, Colorado, Nebraska, Kansas, Oklahoma,
Missouri, Arkansas, Kentucky, Tennessee, Virginia, and North Carolina.
Northern parts of Arizona, New Mexico, Texas, Mississippi, Alabama, Georgia,
and South Carolina are also included as well as southern parts of Montana,
South Dakota, Iowa, Illinois, Indiana, and West Virginia. Finally, the
harsh region includes coastal areas in Massachusetts, Rhode Island, New
York, New Jersey, Maryland, and all of Delaware.
At the northern extremes of the harsh region, night insulation should
be considered on direct gain apertures. Otherwise, all passive systems
discussed in 4.1 may be adequate in this region; heating loads are
substantial making conservation measures very important. Despite the large
heating loads, defensive cooling strategies are still required to assure
positive net energy savings.
4.2.2.4 Very harsh climates. The very harsh region includes all of
North Dakota, Minnesota, Wisconsin, Michigan, Ohio, Vermont, New Hampshire,
and Maine; most of Montana, South Dakota, Iowa, Illinois, Indiana, West
Virginia, Connecticut, Pennsylvania, and Massachusetts; and parts of
Washington, Idaho, Wyoming, Nebraska, Kentucky, Virginia, Maryland, New
Jersey, and Rhode Island.
Near the boundary between the harsh and very harsh regions or in areas
with greater than average sunshine, direct gain systems without night
insulation may still be viable provided the aperture is kept fairly small.
Thermal storage walls and sunspaces will function well in this region
although night insulation may be desirable near the northern boundary; TAPs
are a good choice because arbitrarily high levels of fixed insulation can be
placed between the collector surface and the living space. Heavy use of
conservation measures is critical to performance in the very harsh region.
Defensive cooling strategies, though less of a concern than in regions with
milder winter climates, should not be ignored.
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