Chapter 24 Energy Conservation
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Building materials
Infrared imagery shows an increase in
temperature in many areas of the country,
especially near malls and large buildings. The
buildings and the large blacktop parking lots
absorb heat from the sun. These heat islands
raise the temperature of the surrounding areas.
The areas in and around these heat islands
experience higher air conditioning costs.
Consequently, people have been looking
for ways to reduce the heat, and thus reduce
the necessary cooling of these areas. One
idea is to increase the albedo (refl ective
ability) of the surfaces so they do not absorb
as much sunlight. Increasing the albedo
means a possible reduction in the peak elec-
trical demand of the surrounding area and
in reducing cooling costs. One way to raise
Figure 24-8. Cutaway view of a triple-pane
window.
Figure 24-9. This glass building is located just
outside of Minneapolis, Minnesota.
Figure 24-10. The holes in porous concrete allow
water to run down into the ground underneath the
concrete.
Figure 24-11. A porous concrete driveway in
Atlanta, Georgia.
the albedo is by changing the roof to lighter-
colored and more refl ective materials.
Changing the material of parking lots
could help cool the parking lot surfaces. One
material with this potential is called porous
concrete, Figure 24-10. Normal concrete
and blacktop surfaces force rainwater away
from the area they cover rather than into the
ground. Porous concrete provides a higher
void content and allows water to seep into
the ground. The water can help keep the area
cool. This material is designed for low-traffi c
areas, such as driveways and parking lots,
Figure 24-11. Porous concrete is also lighter-
colored than blacktop, which increases the
albedo and reduces the heat buildup.