Masonry Magazine July 1977 Page. 7
FEA Study Shows Energy/Cost Savings with Masonry Walls
The thermal properties of masonry walls, which reduce heating expenses in winter and cooling expenses in summer, have always been important-but never more so than in our present-day era of high and rising energy costs.
Just how important these masonry thermal properties are to modern building owners and managers is shown by a recent Federal Energy Administration (FEA) study which revealed that the annual heating-cooling costs of a 15-story, 219,000-square-foot building are almost twice as high when the exterior is a reflective glass curtain wall than when it is a 12-inch, uninsulated masonry wall. The differences are even greater when the masonry wall is insulated.
FEA's study was an analysis of the National City Bank Building in Austin. Texas, performed by the consulting firm of Ham-Mer Consulting Engineers. FEA commissioned the consultants to conduct retrofit studies on existing structures that could be used in an energy conservation manual.
In the course of the study, Ham-Mer Consulting Engineers analyzed ways the National City Bank could be retrofitted with different facades to conserve energy. These different exteriors were studied:
* An 80 percent glass facade, shaded.
* An 80 percent glass facade, unshaded.
* An 80 percent insulated glass facade.
* A 12-inch concrete block and brick wall, uninsulated, with 40 percent glass window area.
* A 12-inch concrete block and brick wall, insulated, with 40 percent glass window area.
* A 12-inch concrete block and brick wall, insulated, with no windows.
The study results indicate that the least costly, most energy efficient exterior wall material was the insulated 100 percent masonry facade, which cost $4.210 annually in heating and cooling expenses (see Figure 1).
The most expensive facade we the 80 percent glass sunlit, which cost $27,290 annua The other facades and their annual heating and cooling. s were:
* 80 percent reflective glass, sunlit-$17.240.
* 80 percent glass, shaded-$15,130,
* 40 percent glass and 12-inch masonry-$9,565.
* 40 percent glass, 12-inch masonry insulated-$8,080.
This government-sponsored study indicates why building designers and owners, as well as the masonry industry itself, have been devoting considerable time to the task of achieving greater understanding of the thermal properties of masonry.
The masonry industry, which includes craftsmen, contractors and the producers of masonry materials such as brick, block, stone, plaster, and ceramic structural and facing tile, has, through the Masonry Industry Committee, developed its own study to quantify the superior thermal performance of masonry walls and to provide a method by which designers could use this differential in designing building envelopes and heating-cooling systems.