This article was originally published in the May/June 1994 issue of Home Energy Magazine. Some formatting inconsistencies may be evident in older archive content.



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Home Energy Magazine Online May/June 1994

The National Energy Audit

Oak Ridge National Laboratory (ORNL) developed the National Energy Audit (NEAT) for use in the Low-Income Weatherization Assistance Program (WAP). The computerized energy audit for site-built residential and small multifamily buildings is public domain software that runs on any IBM-compatible computer.

After evaluating numerous energy audits, the Nebraska State Energy Office adopted NEAT for WAP. We selected NEAT for its ease of use, its ability to evaluate the building shell, heating system and cooling retrofit measures, and its method of selecting the most cost-effective measures. The majority of the energy algorithms used in NEATwere taken from the Computerized Instrumented Residential Audit (CIRA), which was developed at Lawrence Berkeley Laboratory in the late 1970s. (CIRA was later commercialized as EEDO, for Energy Economics of Design Options.)

NEAT evaluates energy conservation measures applicable to both hot and cold climates. It can be used to perform site-specific energy audits or to develop a list of conservation measures for homes with similar construction. The audit

  • Includes building-shell, heating-system, and cooling-system energy conservation measures.

  • Accounts for the interaction of savings between measures.

  • Can use measured infiltration rates and heating system efficiency measurements.

  • Ranks energy conservation measures by a savings-to-investment ratio (SIR).

Based on information entered by the auditor, NEAT selects the most cost-effective measures. For example, NEAT will calculate a SIR for R-11, R-19, R-30 and R-38 attic insulation and selects the level of insulation with the highest SIR. NEAT can also be adapted to any conservation program by allowing the user to select the appropriate measures for their program.

Auditors collect information with forms that describe the building's construction, using a series of menu selections. This method of collecting data does not require laborious computations to calculate building-component R-values. Through data entered by the auditor, NEAT calculates the R-values. For example, the software calculates the R-value of a wall based on the information entered by the auditor describing the type of exterior siding, level of insulation, and the type of framing. If data are not available, the auditor can use default values provided during data entry.

Databases reduce data collection requirements. A material-cost database is used to calculate project costs, eliminating the need for the auditor to calculate costs for each measure. Material-cost databases are easily modified by the user. The auditor is not required to collect weather data either, since weather data for both heating and cooling is stored in weather files which are selected by the user prior to running the audit.

NEAT does not require the auditor to collect fuel consumption data or fuel costs for each home. It computes whole-building energy consumption based on data supplied by the user. Fuel-use modeling is more accurate, since the weatherized home will most likely be occupied by different people during the years following the installation of the conservation measures. However, the auditor may choose to adjust the predicted savings by entering actual heating and cooling fuel-consumption data (natural gas and electricity).

Data input screens are similar to the data collection forms, and data entry is further simplified by the use of codes describing building characteristics. NEAT provides default values and checks for errors during data entry. If the value entered is outside the acceptable range, or if the user does not enter an acceptable menu selection, the user is notified of the error and presented with a list of acceptable values or options.

The program also evaluates the feasibility of installing some measures. For example, it evaluates the space available to install attic insulation before selecting the level of insulation to install. This ensures that NEAT will not call for the installation of R-38 attic insulation in an attic with a 6-inch clearance.

The report generated by the software details the annual predicted heating and cooling energy and dollar savings for each recommended measure. Annual savings are listed in dollars, and total energy saved (for electricity and heating fuel) in million Btu. The audit report also lists the individual and cumulative costs of installing the recommended measures, as well as the individual and cumulative SIR for each recommended measure computed over the measure's lifetime. To assist in selecting measures and determining when to stop, the audit report ranks measures three ways: individually, by cumulative SIR, and by total project cost. An auditor can stop when a predetermined SIR or project cost is reached. The audit also generates a work order listing the material type and quantity to be installed.

--Kent Harner

Kent Harner is with the Nebraska State Energy Office in Lincoln.


Recipe for a DOE-Approved Computer Energy Audit

  • Energy savings calculations must take into account local heating or cooling degree days, or audit algorithms may use binned or hourly weather data in energy savings calculations.

  • The audit must use reasonable methods and assumptions.

  • The figures used for the lifetime of the materials and their costs and installation must be generally accepted in the relevant trade.

  • Audit procedures must consider the rate of energy use.

  • Where cooling needs are significant (over 2,000 cooling degree-days per year), the audit must consider cooling measures.

  • Audits must make provisions for the use of advanced diagnostic and assessment techniques (such as blower doors, infrared cameras, various furnace testing procedures, health and safety testing, duct leakage testing, and so on), consistent with sound engineering practices.

  • The audit must determine energy use from actual energy bills or by generally accepted engineering calculations.

  • The audit must determine that each weatherization material is cost-effective by ensuring that the discounted savings-to-investment ratio (SIR) is greater than or equal to one. The SIR must account for costs of material, labor, and on-site supervisory personnel.

  • The audit procedures must assign priorities among materials in descending order of SIR and must account for interaction between architectural and mechanical measures. After adjusting the estimated fuel cost savings for interaction between measures, the audit must eliminate any measure whose interaction-adjusted SIR is less than one.

  • The audit must ensure the overall SIR for the entire package is greater than or equal to one.

  • Dwellings must be treated as a whole system by examining the heating and cooling system, the air-exchange system, and occupant habits and needs, and making necessary adjustments to the priority of weatherization materials in response to these examinations.

  • The audit must provide for use of an annually adjusted discount rate.

  • Priority lists, if used, must be developed by conducting site-specific energy audits of a representative sample of typical dwelling units for each major dwelling type covered by the state's weatherization program. Priority lists must be reevaluted every five years.

  • Lists of presumptively cost-effective general heat waste (GHW) reduction weatherization materials are subject to DOE approval and must state the circumstance under which such materials may be presumed cost-effective.

    Source: Weatherization Program Notice 93-8, March 26, 1993, U.S. Department of Energy.



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Computerized Energy Audits (Penn)
Confessions of an 'Addicted' Auditor (Padian)
Measuring the Performance of the National Energy Audit (Sharp)
New York's 'Targeted Investment Protocol System' (Gerardi and Sweeney)
Selecting an Infrared Imaging System (Snell)
Training Guide for 'Total Comfort' Professionals
Using Fuel Bills for a Targeted Investment (Padian)
The Wisconsin Audit System (O'Leary)

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