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
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 is with the Nebraska State Energy Office in Lincoln.
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