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 nonmasonry wall systems. SmartWall Systems offers superior
performance, especially in terms of energy efficiency, maintenance,
appearance, fire resistance, durability, and strength to weight
ratio.
The builtin
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 thirtyyear period.
The analysis
compares SmartWall Systems concrete masonry units at 90 lb/ft^{3}
density to ordinary 135 lb/ft^{3}
units. Units are standard 8" x 8" x 16" dimensions.
The analysis uses steadystate 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/ft^{3}

105 lb/ft^{3}

90 lb/ft^{3}

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

Rvalue
in (hr • ft^{2} • ºF) / BTU. U value
in BTU / (hr • ft^{2} • 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/ft^{3}
units. The second comparison (in the right hand column) is between
a SmartWall Systems unit at 90 lb/ft^{3}
and the same 135 lb/ft^{3}
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/ft^{3}
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 5759.
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) Rvalues
for Single Wythe Concrete Masonry Walls, TEK 62A, National Concrete
Masonry Association, 1996. The Rvalue 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/ft^{3}
wall and 135 lb/ft^{3}
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 longterm two percent difference
between shortterm US Tbill rates and the CPI inflation rate. See
Office of Management and Budget Circular A94 Guidelines and Discount
Rates for BenefitCost 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
