reaching the market reflect most of the incident thermal energy. Early tests of these products in Miami

show a cooling energy savings of 20 to 30 percent with a simple payback period of one to two years.

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Second, research efforts are underway to develop  smart  roofing materials that absorb solar energy when

the outdoor temperature is cool and reflect solar energy when the outdoor temperature is warm.

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Because roof surfaces are replaced on regular, albeit long, intervals, these technology opportunities are

pertinent for both new and existing buildings.

Wall Systems

Wall systems include framing elements and insulated cavities. In traditional wall designs, the

framing portions of the wall are not insulated and represent a much greater portion of the total wall

surface than is generally realized. New wall designs minimize heat loss by as much as 50 percent by

reducing the amount of framing used and by optimizing the use of insulated materials.

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These designs

include optimal value engineering, structural insulated panels, and insulated concrete forms.

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Even with

conventional wall design, minor modifications can significantly reduce energy transport. For example,

polyurethane bearing blocks have twice the insulating capability of wood and can be used to thermally

isolate steel walls from foundations and from steel attic beams.

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Improved wall system designs, however, generally apply only to new construction; the options for

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walls in existing buildings are more limited. Insulated sheathing is available for wall retrofits but often

requires modifications to window jambs and doorframes. In the long term, the coatings under develop 

ment for roofs could become a constituent of siding materials. Another approach is to take advantage of

new insulating fabrics that could be hung from or applied to interior wall surfaces. The reflective proper 

ties of such materials can also be engineered to provide greater human comfort at reduced (winter) or

elevated (summer) indoor temperatures, further increasing the energy savings.

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Windows

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Energy travels through windows via radiant energy, heat conduction through the frame, and air

leakage around the window components. The higher quality windows on the market today address all three

of these energy paths, and they can be six times more energy efficient than lower quality windows.

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Low E coatings for windows reduce the flow of infrared energy from the building to the environment,

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Towards a Climate Friendly  

Built Environment

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