Low Income Weatherization Assistance Program

Energy Savings Analysis

August 16, 1996
Nebraska Energy Office

Table of Contents

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The Low Income Weatherization Assistance Program is a federally funded program for weatherizing homes to save money and energy. It is administered by the Nebraska Energy Office. The objective of the program is to increase the energy efficiency of dwellings occupied by low-income persons in order to reduce their energy consumption, thus lowering their energy bills while simultaneously increasing the comfort of their homes. The program targets vulnerable groups including the elderly, people with disabilities and families with children.

This report presents the results of an evaluation of the energy savings and cost effectiveness of the program based on a sample of homes weatherized during May-September 1994.


May, 1995: Decision was reached to perform an analysis of the Low Income Weatherization Assistance Program. Further, it was decided to select homes for the study from those weatherized in the period May 1, 1994 - September 30, 1994. Also, only the impact on heating fuel use was to be evaluated. Homes were selected from this time period so that only one request for energy consumption data covering the 12 month period prior to weatherization and the 12 month period immediately after weatherization would be made to fuel suppliers, and so all requests for data could be completed by late summer 1995. A random sample of 247 weatherized homes and 3 multi-family units was selected from the target group.

June, 1995: As part of the request for weatherization assistance, each participant signed a fuel information release form permitting access to past, present and future fuel billing information. Copies of these releases for the sampled homes were requested from the nine Weatherization Subgrantees during the second week of June and all requested releases were received by June 27, 1995.

July, 1995: A list of fuel suppliers from whom data would be requested was begun. A list of sampled homes was prepared for each identified fuel supplier. Preparation of the list of fuel suppliers was more difficult than anticipated for the following reasons:

August, 1995: The list of fuel suppliers with complete addresses was completed. A request was made to the subgrantees for a letter authorizing the Nebraska Energy Office to collect data for the analysis on behalf of the agencies. The last letter was received on September 15, 1995.

September, 1995: Letters were mailed to 57 fuel suppliers requesting data on fuel consumption of 224 sampled homes and 1 multi-family housing unit during the last week of September. Data was not requested on the remaining homes sampled, primarily because the current resident had not lived there for 12 months prior to participation in the weatherization program.

October, 1995: Data was received and reviewed for 95 homes and the multi-family housing unit. Phone conversations with the fuel suppliers for nearly 100 additional homes revealed that only 14-16 months of data were maintained on their computer systems and that it would be extremely time consuming for them to retrieve it from their archives. Since adequate useable data had been received, it was decided not to pursue this data. Replies from suppliers concerning an additional 12 homes indicated that they did not sell fuel to the specified customer(s).

November, 1995 - March, 1995: Energy data and weather data were entered in PRISM Advanced Version 1.0. PRISM is a computer program developed by Princeton University to estimate annual energy consumption, normalized for weather.

March, 1996: Weather data from the publication Climatological Data, Nebraska published by the National Oceanic and Atmospheric Administration, Asheville, North Carolina was required for the analysis. The last such weather data was received in late March.

April, 1996 - June, 1996: Data analysis and evaluation performed.

Summary Results

Homes weatherized by the Low Income Weatherization Assistance Program have reduced energy consumption, reduced energy bills and reduced emissions of greenhouse gases.

The average home weatherized during program years 1993/94 and 1994/95 saved an average of 18.7% of total consumption of the fuel used for heating. This resulted in an average reduction of $126 in annual utility bills. Due to the decrease in energy use, these homes also contributed to reducing emissions of greenhouse gases. On average, each home reduced carbon dioxide emissions by 2,297 pounds, sulfur dioxide emissions by 0.435 pound, and nitrogen oxides by 0.706 pound.

Sample and program results are presented in the following sections of this report.

Sample Results

Data for 62 homes was found suitable for input into PRISM for further analysis. For most of those found not suitable, data was only provided for 14 months because that was all the fuel supplier had readily available on the computer. An additional two homes were dropped from analysis when the estimates of annual consumption from PRISM were rated as statistically unreliable.

The 60 homes in the final analysis were grouped as follows:

In addition, the data from the one multi-family housing unit was analyzed.

Energy savings for the sample are summarized in the following table:

Group Sample Size Heating Fuel Pre-Wx Use
Post-Wx Use
% Savings
Mobile 13 natural gas (10)
propane (2)
electricity (1)
121.6 108.1 13.5 11.1
Frame - fossil fuel 37 natural gas (26)
propane (10)
heating oil (1)
109.9 84.9 25.0 22.7
Frame - electricity 10 electricity (10)
Multi-family** 1 natural gas 2,172.4 2,026.1 146.3 6.7

* site refers to Btu content at point of end-use (3,413 Btu/kWh)

* source refers to Btu content of fuel used to generate electricity (10,450 Btu/kWh)

** 1 multi-family housing facility with 17 weatherized units

Single family frame homes heated by fossil fuels realized the greatest energy savings of 22.7% of total fuel use, next was mobile homes at 11.1%, single family frame homes heated by electricity 10.5%, and multi-family housing units 6.7%.

Costs and dollar savings for the sample are summarized in the following table:

Group Costs, Total Costs, Labor and Materials Costs, Materials Average Dollars Saved Simple Payback (in years) Discounted Payback (in years)
Mobile 1,764 1,374 883 90 9 27
Frame - fossil fuel 2,105 1,715 954 141 14 20
Frame - electricity 1,108 718 399 142 7 10
Multi-family 10,318 3,688 1,963 778 13 18

The dollars saved considers only the savings due to reduced heating fuel consumption, and would be expected to be higher for all but the electrically heated homes due to additional savings on air conditioning bills during the summer months. Also, no attempt has been made to include the dollar benefits associated with the employment impact of the weatherization program, the economic benefit of reduced greenhouse gas emissions, the value of increased comfort in weatherized homes, as well as other benefits due to the program. Total costs include only those directly attributed to the weatherization work and do not include administrative costs of the Nebraska Energy Office nor the Weatherization Subgrantees.

It is assumed that work performed under the weatherization program has a useful life of 20 years. Thus, energy savings alone pays for the weatherization work in all groups when using simple payback, and for all but mobile homes when considering the discounted value of costs and benefits.

Program Results

During the 1993/94 and 1994/95 program years covered by the above sample of weatherized homes, a total of 3,721 units were weatherized. These homes were categorized into the groups above based on information maintained by the Weatherization Division of the Nebraska Energy Office, the original sample selected, and census information about the source of heat for Nebraska homes. In summary, it is assumed that the weatherized units were:

A summary of the energy savings by fuel type is presented in the following table for all homes weatherized during program years 1993/94 and 1994/95. These savings are presented in both physical units and million Btu. The million Btu savings are also provided for the 20 year life of the projects.

Fuel Type Physical Units 1st Year Savings 20 Year Savings 1st Year million Btu Savings 20 Year

million Btu Savings

Natural Gas therms 541,357 10,827,142 54,136 1,082,714
Heating Oil gallons 41,694 833,901 5,783 115,662
Propane (LPG) gallons 153,623 3,072,461 14,671 293,420
Electricity kWh ..Btu-site ..Btu-source 850,864 -- -- 17,017,580 -- -- -- 2,904 8,892 -- 58,081 177,834
Total Btu Savings site source -- -- -- -- 77,494 83,482 1,549,877 1,669,630

Total first year program savings of 77,494 million Btu represent an 18.7% reduction in site energy use, or the first year program savings of 83,482 million Btu represent an 18.0% reduction in source energy use.

Total first year energy bill dollar savings was $468,064 compared to a total weatherization cost of $6,961,053. This represents a simple payback in the 14th year for energy savings alone. In discounted dollars, payback occurs in the 20th year.

Although a discounted payback in the 20th year does not look very impressive, one should keep in mind that the following benefits have not been included in the economic analysis:

Reduction in Greenhouse Gas Emissions

In addition to reducing energy consumption and thus the energy bills, homes that are weatherized are also benefitting society because of the reduction in greenhouse emissions resulting from their reduced energy use. First year reductions by fuel type and greenhouse gas are summarized in the following table:

Fuel Source Carbon Dioxide (short tons) Sulfur Dioxide (pounds) Nitrogen Oxides (pounds)
Electricity * 466.5 1,325.5 813.9
Heating Oil 381.5 286.5 166.4
Natural Gas 2,600.0 5.2 1,013.6
Propane 836.5 2.1 633.9
Total 4,284.5 1,619.3 2,627.8
* - emissions for electricity weighted by fuels used to generate electricity in Nebraska


The following list of recommendations, are primarily predicated on the fact that there will be another evaluation of the program sometime in the future.


National Impacts of the Weatherization Assistance Program in Single-Family and Small Multifamily Dwellings, by Marilyn A. Brown, Linda G. Berry, Richard A. Balzer, and Ellen Faby. Oak Ridge National Laboratory, Oak Ridge, Tennessee (1993).

PRISM (Advanced Version 1.0), Computer program developed by Center for Energy and Environmental Studies, Princeton University, Princeton, New Jersey (1995).

BLCC4 4.3-96 and EMISS 1.0, Computer programs developed by U.S. Department of Commerce, National Institute of Standards and Technology, Washington, DC (1995).

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Nebraska Energy Office

P.O. Box 95085

Lincoln, NE 68509

Phone: (402) 471-2186 || FAX: (402) 471-3064

email: energy@nebraska.gov