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where a the adjustment factor for marginal cost, such adjustments can be simulated by dividing the appropriate energy price by this adjustment factor. This adjusted energy price can be used as a "ref43 erence" energy price for finding the optimal level of investment in the ECT under examination.

As an example, consider the case of insulation used for winter heating savings (no cooling load) with a fuel priced at $.45/100,000 Btu delivered (efficiency considerations accounted for). Suppose that the variable costs of such insulation were raised by 10% (an adjustment factor of 1.1) over the costs shown in Appendix B. In this case a reference energy price of $.41 (.45/1.1) will simulate the effect of the cost differential. Note that relatively small changes in ECT costs (<20%) will have small practical effects on the optimal levels of investment.

5.2 Tabular Results

Tables 5.2A through 5.2H present the estimates of optimal energy conservation combinations for a variety of climates and a wide range of energy prices. In the case of attic and wall insulation, several insulating materials are examined: loose fill glass fiber (R-2.2 per inch), glass fiber batt/blanket (R-3.1 per inch), and loose fill cellulose (R-3.7 per inch in attics and R-3.3 per inch in walls). Insulation in ceiling and floors is examined in the case of no existing insulation and for an existing R-11 base (equivalent to 3.5 inches of glass fiber batt/blanket). Walls are assumed uninsulated; if any insulation exists, blown-in insulation is not practical and unlikely to be cost effective. Duct wrap for insulating heating and cooling ducts in unheated areas is examined. Insulation should be raised to the level shown. (Duct connections should be retaped first, if necessary). Data shown are for ducts in attic spaces.

For crawlspaces, garages or unheated basements, the duct estimates for winter degree days only will provide a better guide than those tables showing both heating and cooling requirements.

Minimum storm window sizes that appear cost effective are shown in the tables; sizes 2' x 2' through 4' x 6' were examined for both loose and average fitting, weather-stripped, double-hung, wood-frame prime windows. Results do not appear to vary significantly for these two types of windows once weather stripped. Savings from storm windows over casement windows and fixed (non-openable) windows may be similar as well.

Payback periods are shown for a 3' x 5' window in order to give some indication of the payback period for average size windows. Both winter heating and summer cooling savings are considered.

Storm doors, on the other hand, are considered for winter heating savings only (screen inserts are generally more useful for natural ventilation during the non-heating months.) Energy savings due to the use of storm doors are based on an assumed wooden, weather-stripped prime door, 1.5" thick, size 3' x 6'8", with glass composition ranging from 0 to 50%. Again both loose and average fitting units were examined and found to be similar in savings potential. Results shown are for average fitting prime doors. Prime doors with window sections lose more heat than solid doors under similar thermal loading conditions so that energy savings generated by storm doors increase as the percentage of glass in the prime door increases. In some cases the application of storm doors to prime doors with glass components will be cost effective even while application to solid doors is not. (In Tables 5.2A-H, applications of storm doors which appear to be economical are marked with an x followed by the minimum percentage of glass in the prime door that makes their use justifiable from an economic standpoint.)

43.

This will not provide exact solutions in those tables (5.2 F-H) which involve both heating and cooling loads because the two sets of energy prices used are not strictly proportional. Note that only changes in variable costs need be adjusted for; changes in fixed costs will have no effect on optimal levels unless they are so high as to eliminate all net savings.

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$.60

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Years to
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Additional
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Years to
Pay Back
Additional
Inches
Years to
Pay Back
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"Equivalent to 31⁄2" of Glass Fiber Batt/Blanket Insulation

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A

Loose Fill Glass Fiber (R-2.2 per inch)

B - Glass Fiber Batt/Blanket (R-3.1 per inch) (not applicable to finished walls)

C - Loose Fill Cellulose Fiber (R-3.7 per inch in attic/R-3.3 per inch in walls)

0 - Glass Fiber Duct Wrap (R-4 per inch)

1. Floor Over Unheated Basement. Crawlspace, or Garage

2 Minimum Economical Size: Payback for 3'x5' Storm Window 3. Refers to Minimum Glass Composition of Primary Door That Makes Storm Door Economical (10 year life)

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Equivalent to 3% of Glass Fiber Batt/Blanket Insulation

A Loose Fill Glass Fiber (R-22 per inch)

B- Glass Fiber Batt/Blanket (R-31 per inch) (not applicable to finished walls)

C

Loose Fill Cellulose Fiber (R-37 per inch in attic/R-3 3 per inch in walls)

D - Glass Fiber Duct Wrap (R 4 per inch)

1. Floor Over Unheated Basement, Crawlspace, or Garage

2 Minimum Economical Size, Payback for 3'x5' Storm Window

3 Refers to Minimum Glass Composition of Primary Door That Makes Storm Door Economical (10 year life)

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OPTIMAL ENERGY CONSERVATION COMBINATIONS

6000 Degree Days;.

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Cooling Hours. (Avg to); 20 Year Life

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Additional
Inches
Years to
Pay Back (2) (2) (2) (6) (5) (6) (1) (2) (2) (4)
"Equivalent to 3% of Glass Fiber Batt/Blanket Insulation

A Loose Fill Glass Fiber (R-2.2 per inch)

B- Glass Fiber Batt/Blanket (R-31 per inch) (not applicable to finished walls)
C- Loose Fill Cellulose Fiber (R-37 per inch in attic/R-3.3 per inch in walls)

0 - Glass Fiber Duct Wrap (R-4 per inch)

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1. Floor Over Unheated Basement, Crawlspace, or Garage

2 Minimum Economical Size, Payback for 3'x5' Storm Window 3. Refers to Minimum Glass Composition of Primary Door That Makes Storm Door Economical (10 year life)

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