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ESCSI INFORMATION SHEET 3530 - MARCH 2000

Life Cycle Energy Cost Analysis
Shows That SmartWall Systems Provides Significant Savings in All Climates

SmartWall Systems is a concrete masonry wall system that outperforms other masonry and non-masonry wall systems. SmartWall Systems offers superior performance, especially in terms of energy efficiency, maintenance, appearance, fire resistance, durability, and strength to weight ratio.

The built-in thermal resistance and low thermal bridging of SmartWall Systems saves energy in both warm and cold climates.

The Life Cycle Cost analysis illustrated in the graph uses local climate data and energy costs for heating and cooling, and show the significant life cycle energy cost savings achieved by SmartWall Systems. In many cases the present value of these savings will pay for the SmartWall System itself. For example, the analysis shows that a SmartWall building in Omaha saves $1.15 per block over the first ten years of the building’s life, and $2.86 over a thirty-year period.

The analysis compares SmartWall Systems concrete masonry units at 90 lb/ft3 density to ordinary 135 lb/ft3 units. Units are standard 8" x 8" x 16" dimensions. The analysis uses steady-state heat flow calculations.

Detailed information on the thermal values, energy costs and the methodology of the Life Cycle Costing analysis illustrated above is shown on the following pages. For more information about SmartWall Systems, contact the Expanded, Shale, Clay, and Slate Institute office or any ESCSI member.

Table 1:
Life Cycle Energy Cost Analysis Present Value of Annual Energy Cost Savings Using SmartWall Systems Over a Thirty Year Period

Wall construction: Single wythe 8" w/foamed in place core insulation
Location:
Omaha, Nebraska

R Value Data

CMU Density

.

135 lb/ft3

105 lb/ft3

90 lb/ft3

R value (3)

3.40

5.60

7.30

Calc: U value
0.294
0.179
0.137

Calc: Difference in U values
(vs 135 lb//ft
3)

---

0.116

0.157

R-value in (hr • ft2 • ºF) / BTU. U value in BTU / (hr • ft2 • ºF)


The following analysis makes two comparisons. The left column compares lightweight units meeting ASTM C90 at 105 lb/ft
3 to ordinary 135 lb/ft3 units. The second comparison (in the right hand column) is between a SmartWall Systems unit at 90 lb/ft3 and the same 135 lb/ft3 unit. All units are conventional 8" x 8" x 16" size. The analysis Shows that SmartWall Systems units save substantial energy costs when compared to both ordinary 135 lb/ft units and regular ASTM C 90 lightweight units.

Heating Cost Calculations

ASTM Lightweight
105 lb/ft
3 CMU

SmartWall
90 lb/ft
3 CMU

U value difference vs. 135 lb/ft3 cmu (from above)
0.116
0.157
Natural Gas Cost (2) per mcf

$4.53

$4.53

Furnace efficiency

0.80

0.80
Calc: $ Cost per Btu output

5.66E — 06

5.66E — 06

Heating Degree Days for This Location (1)

6201

6201

Calc: Energy Savings: $ / sq ft / yr

$0.0974

$0.1324

Calc: Energy Savings: $ / block / yr
$0.0866
$0.1177
Present Worth of Heating Savings n (years)
30
30
i (nominal rate — energy and money)(4)
2.00%
2.00%

Calc: Present Worth of Heating Energy Savings,
$ / block

$1.94

$2.64


Cooling Cost Calculations

.

.

Electricity Cost (2) per kwh

$0.0538
$0.0538
SEER
10
10
Cooling Degree Hours for This Location (1)

13180

13180

Calc: Energy Savings: $ / sq ft / yr

$0.0082

$0.0111

Calc: Energy Savings: $ / block / yr
$0.0073

$0.0099

Present Worth of Cooling Savings n (years)
30
30
i (nominal rate — energy and money) (4)
2.00%
2.00%

Calc: Present Worth of Cooling Energy Savings,
$ / block

$0.16

$0.22


Calc: Present Worth of Total Energy Savings,
$ / block

$2.10

$2.86

Table 2:
Life Cycle Energy Cost Savings by City for Ten and Thirty Year Periods with Climate and Energy Costs

 


References for Table 1 and Table 2:

(1) Appendix A, Climatic Data for the US and Canada, ASHRAE 90.2, 1993.

(2) Natural Gas Costs: Natural Gas Monthly, US Department of Energy – Energy Information Administration, October, 1999. Table 22, page 57-59. Commercial gas costs by state were used for the most recent complete year available. Contact ESCSI for details.

Electricity Cost: Electric Sales and Revenue 1998, US Department of Energy – Energy Information Administration, October 1999, Table 15. Commercial Average Rates for the Utility serving the selected city.

(3) R-values for Single Wythe Concrete Masonry Walls, TEK 6-2A, National Concrete Masonry Association, 1996. The R-value is interpolated for 90 pcf. Values are for unreinforced walls. For walls with 32" o/c vertical grouting and reinforcing, the difference in U values between a 90 lb/ft3 wall and 135 lb/ft3 wall drops to 0.153, a 2.5% reduction. Life cycle savings will be reduced by a similar amount. Calculation procedures for grouted walls are shown in the
referenced NCMA TEK.

(4) The 2% nominal discount rate was chosen as appropriate for this analysis because it represents the typical long-term two percent difference between short-term US T-bill rates and the CPI inflation rate. See Office of Management and Budget Circular A-94 Guidelines and Discount Rates for Benefit-Cost Analysis of Federal Programs.

This analysis was developed by Buildex Inc. for use with permission by members of the Expanded Shale, Clay, and Slate Institute, Salt Lake City, Utah and is © 2000 ESCSI. This March 2000 edition replaces earlier versions of this publication, which used different furnace efficiencies and cooling SEER and a less comprehensive source of commercial electricity costs.

 


ESCSI INFORMATION SHEET 3530 - MARCH 2000