Weatherization Assistant Features
The Weatherization Assistant is a family of easy-to-use but advanced computer audit software programs that select energy-efficiency retrofit measures for homes to be weatherized. The Weatherization Assistant is designed to assist states and local weatherization agencies implement the U.S. Department of Energy (DOE) Weatherization Assistance Program. It serves as the umbrella program for the National Energy Audit Tool (NEAT) and the Manufactured Home Energy Audit (MHEA).
The Weatherization Assistant features a Windows graphical user interface. Data input is provided to the program through Microsoft Access® forms which can be used in either “form” view (data are displayed on forms which are filled in) or “datasheet” view (as would be seen in a spreadsheet application). All input and output data are stored in a relational database, enabling interaction with other management or financial database tools. Context-sensitive help is available for all input fields.
In addition to serving as the umbrella program for NEAT and MHEA, the Weatherization Assistant (Version 8) provides many optional features that are useful in implementing and administering weatherization programs. These optional features include:
- Extensive contact information for agency personnel, clients, contractors, and material suppliers;
- Expanded client application information;
- Recording of health and safety issues, with automatic generation of health and safety retrofit measures if desired;
- Recording of space-heating system, water heater, and blower door diagnostic measurements;
- Detailed work orders which can be generated either automatically from NEAT or MHEA recommendations or from user-defined listings of measures;
- Status tracking of clients, applications, audits, work orders, inspections, and contractor payments;
- Tracking of payments and balances in multiple funding sources;
- An inventory of materials and supplies automatically updated by completed work orders;
- Report generation;
- A Geographic Information System (GIS) which allows mapping of each individual dwelling or any group of dwellings; and
- Ability to attach digital photos to each client, audit, or work order.
NEAT and MHEA
NEAT is specifically designed for site-built single-family houses while MHEA is designed specifically for mobile homes. The unique construction characteristics of mobile homes require evaluating and installing measures specifically for such homes in order to obtain effective weatherization with high energy and dollar savings. NEAT and MHEA evaluate each home individually after taking into account local weather conditions, retrofit measure costs, fuel costs, and specific construction details of the home. After describing envelope components, heating and cooling systems, and base load equipment (e.g., refrigerators, water heaters, lighting), NEAT and MHEA produce a prioritized list of cost-effective weatherization measures customized for the dwelling being evaluated. The output includes estimates of the dollar value for the projected energy savings, savings-to-investment ratios (SIRs), installation costs, a list of the quantities of the major materials necessary to perform the recommended weatherization retrofits, and design heating and cooling loads needed to size any replacement equipment.
NEAT was developed by the Oak Ridge National Laboratory. NEAT was formally introduced in the summer of 1993 and was already being used by local weatherization agencies throughout 20 states by 1994. During 1995, NEAT was used by approximately 500 local weatherization agencies in 30 states to make retrofit decisions for more than 80,000 low-income dwellings. Based on field tests in Wisconsin, New York, and North Carolina, NEAT has helped energy auditors improve average space-heating energy savings by 18 to 25% over standard measure selection methods.
MHEA was originally developed by the National Renewable Energy Laboratory. Modifications and conversion to a Windows-based program were performed by the Oak Ridge National Laboratory, which now maintains and supports the software. MHEA stands apart from other building energy analysis tools in many ways. Input and calculations incorporated into the software address constructions unique to mobile homes such as bellied floors and bowstring roofs. The retrofit measures evaluated by MHEA are all applicable to mobile homes. Help messages describe common weatherization practices for mobile homes and provide hints on how to install retrofit measures.
NEAT and MHEA Implementation
NEAT and MHEA follow eight steps to select the energy efficiency measures for a particular home that meet a user-defined level of cost effectiveness (i.e., measures that have an SIR greater than a value selected by the user):
1. NEAT and MHEA guide the user through the process of entering data on the home that describe the characteristics of the home, its mechanical systems, and other energy-related information. NEAT and MHEA also allow health and safety deficiencies and repair items to be noted. Both programs use blower door measurements, duct leakage measurements, and steady-state efficiency measurements of space-heating equipment if available. Data may be collected in the field using data input forms and transferred to NEAT or MHEA later in the office, or data may be entered directly into NEAT or MHEA using a portable computer while auditing the home.
2. NEAT and MHEA use engineering calculations and weather data from one of 216 weather cities in the U.S. to compute the annual heat loss and heat gain of the home, and the annual space-heating and space-cooling energy consumption required to keep the home at a specific thermostatic set point. Both programs calculate heat loss and heat gain on a monthly basis using a variable-base degree-day method and ten-year average weather data for the selected city. They also consider the amount of solar energy absorbed by a home and the typical amount of heat generated inside a home by people and their refrigerators, water heater, other appliances, and lights. NEAT and MHEA use ASHRAE Draft Standard 152P algorithms for estimating the heat gain and loss due to duct leakage if specified. NEAT and MHEA assume a home is maintained at average conditions regardless of specific occupants because efficiency measures typically remain after occupants move, and this follows the intent of the Weatherization Assistance Program that finances energy efficiency measures that generate savings for up to 20 years.
3. NEAT and MHEA compute the energy consumption of selected baseload uses (water heating, refrigerators, and lighting in need of retrofit) if desired. Refrigerator and water heater descriptions use an extensive database of manufacturers and models which eliminate the need to input detailed equipment descriptions by the user.
4. NEAT checks the applicability of 34 building envelope, space-heating and space-cooling system, and baseload energy efficiency measures to the specific home being audited, while MHEA checks the applicability of 31 measures. These measures include air and duct leakage reduction, envelope insulation, window replacements and other treatments, space-heating and space-cooling equipment replacement and tune-up, replacement refrigerators, water heater tank and pipe insulation, replacement lighting, and more. Both programs then calculate an energy savings and discounted SIR for each applicable measure applied individually to the home. User-defined energy efficiency measures can also be entered and evaluated. The SIRs are calculated using fuel costs and installation costs representative of the home and agency as input by the user, as well as measure lifetimes appropriate for each measure.
5. NEAT and MHEA evaluate the interaction between efficiency measures (e.g., since insulation reduces the amount of energy needed for space heating, it also reduces the energy savings from a space-heating system replacement). Beginning with the measure with the highest SIR, NEAT and MHEA apply each energy efficiency measure to the home and then compute a new SIR for the remaining measures, taking into account savings gained by preceding measures.
6. NEAT and MHEA identify a final list of recommended energy efficiency measures by selecting those with an SIR greater than the cut-off value selected by the user once interactions between measures have been accounted for.
7. NEAT and MHEA generate a report of recommended energy efficiency measures that identifies—both individually and cumulatively—the energy savings, installation cost, and SIR of the recommended measures. The report also identifies those health, safety, and repair items selected by the user that need to be performed. In addition, an essential materials list is developed, and design heating and cooling loads needed to size replacement equipment are provided.
8. NEAT and MHEA can adjust their estimated energy savings based on actual utility consumption data and develop a second list of recommend energy efficiency measures if the user desires.