Masonry Magazine March 1963 Page. 18
Nominal Face Size 51" x 12"-8" Thickness
NATCO DRI-SPEEDWALL TILE
Natco Dri-Speedwall tile is a single, load-bearing "thru-the-wall" unit. Fireproof, Natco Dri-Speedwall tile is virtually impervious to moisture, vermin and decay. It has great load-bearing strength and because of its design and mortar interlocking feature, it is highly resistant to lateral as well as vertical pressure. The texture of Natco Dri-Speedwall tile has the attractive appearance of high-quality face brick. Natco Dri-Speedwall tile is furnished with Buff Unglazed, Salt Glazed and Red Textured finishes. It is also available in nominal 4" thickness for fast, low cost masonry veneer and cavity wall construction, as well as for composite 2-unit 12" and 16" walls. Write for catalog S-62.
NATCO CORPORATION
GENERAL OFFICES: 327 Fifth Avenue, Pittsburgh 22. Pa. BRANCH SALES OFFICES: Boston Chicago Detroit Houston New York Philadelphia Pittsburgh Syracuse Birmingham, Alabama Brazil, Indiana. IN CANADA: Natco Clay Products Ltd., Toronto, Ontario.
18
$ and Sense of Insulating
(Continued from Page 5)
($1.00 per thousand cu. ft. of gas). Interior temperatures were assumed at 70 F in winter and 75 F in summer. Electrical power consumption was based on 500 kwh per month. The air conditioning plant was assumed to have a capacity of 25 tons or less, with a power input of 1 kw per ton. An average orientation of masonry walls was assumed, and their color was assumed to be medium. Variations in color may produce a variation in the thermal economic coefficient for air conditioning costs of plus or minus 15 per cent.
Thermal economic coefficients for heating were prepared for 75 cities of the United States and were shown on a map as shown in Fig. 1. Isobars were drawn at appropriate increments. To find the annual fuel cost per square foot of wall, simply multiply the U value shown in Table 1 by the thermal economic coefficient for heating.
For example, in Albany, New York, the annual cost of fuel attributable to 1 sq. ft. of wall having a U value of .30 would be determined as follows:
The thermal economic coefficient for heating in Albany is found to be 18. The annual cost is therefore 18 x 30, or $.054 per sq. ft. per year. If the U value were .13, the annual fuel cost would be 18 x 13, or 2.3c per sq. ft. per year. The annual saving due to the insulation is therefore 3.1c per sq. ft. per year. If the insulation cost is 10c per sq. ft., the annual return on the investment is 31 per cent.
Similarly, the thermal economic coefficients for heat gain through masonry walls were computed and shown on a map of the United States. Isobars were drawn at appropriate increments. The thermal economic coefficient for cooling for masonry walls is shown in Fig. 2. For example, in New Orleans, Louisiana, the annual cost of electricity for air conditioning attributable to 1 sq. ft. of masonry wall having a U value of 30 would be determined as follows:
The thermal economic coefficient for cooling buildings with masonry walls in New Orleans is found to be .078. The annual cost of electricity per square foot of wall area is therefore .078 x 30, or 2.3c per sq. ft. per year. If the wall were insulated to provide a U value of .13, the annual cost of electricity would be reduced to .078 x .13, or 1c per sq. ft. of wall area. The annual saving attributable to the insulation is 2.3 1.0, or 1.3c per sq. ft. per year.
The Zonolite Company publishes form G-203 to facilitate these calculations. Copies are available upon request.
It is important to recognize the limitations of these figures. The thermal costs determined in accordance with this method do not include all costs of operating the mechanical equipment, e. g.. manpower, maintenance, and water consumption. The figures are therefore conservatively low for non-residential construction. Costs computed by this method ignore income and property taxes.
Although the thermal economic coefficient for heating is applicable to any type of building enclosure, the thermal economic coefficient for cooling shown in Fig. 2 is applicable only to masonry walls. Fuel costs are not considered tax deductible, nor is any provision made for an annual depreciation tax credit on the plant. Property taxes and insurance have been neglected. Only fuel and electricity costs are included.
The method assumes that the initial cost of the air conditioning plant is independent of the heat transmission through the walls. Adjustment for local fuel costs differing from $1.00 per therm may be made by multiplying the coefficient by 10 times the local cost per therm.
All types of costs are constantly changing. The thermal costs determined by this method are therefore subject to change with inflation. Since 1935, the cost of MASONRY March