Note: A concise summary of the initial version of the tool (version 2012) is provided in this paper.
The Scoring Tool is a key component of the U.S. Department of Energy's residential building energy label initiative to support the American Recovery and Reinvestment Act of 2009 (Recovery Act) funded Recovery Through Retrofit plan. The Home Energy Score Program will be the first national asset rating method that allows all USA regions to opt into a simplified and standardized energy assessment process that complements existing advanced home energy audit methods.
The Home Energy Score is designed to provide a rapid low-cost opportunity assessment of a home's fixed energy systems (also known as an "asset rating") and provide the home owner with general feedback on the systems that potentially need more detailed attention from certified home performance diagnostics and weatherization professionals (such as those engaged with RESNET, Building Performance Institute, and the Affordable Comfort Institute).
A set of background research projects and publications informed development of the tool:
A draft report by Newport Partners summarizes findings from 12 consumer focus groups conducted in summer 2010 concerning home energy labeling (here).
A report summarizing feedback from homeowners during the pilot projects conducted in 2011 (here)
A report summarizing feedback from professional Qualified Assessors during the pilot projects conducted in 2011 (here)
The Scoring Tool's accuracy has been documented in detail by the National Renewable Energy Laboratory (here).
The Scoring Tool has been designed to support the existing marketplace for energy analysis tools and services by providing a substantially lower-cost "entry level" assessment (but not a formal work scope or cost estimate), which can help the service provider establish the potential for energy savings and the value of a more comprehensive investigation and retrofit recommendation report. For a typical home, an experienced assessor can complete a Scoring Tool analysis in under an hour, while a comprehensive follow-up assessment could take several times that long.
Also developed within the Scoring Tool are Application Programming Interface ("APIs") services, which third-party energy software developers can use to embed the Home Energy Score methodology into their products and business processes
To ensure that users proactively define asset characteristics, no input values are defaulted and all questions must be answered. For those systems not considered fixed assets, attributes are not adjustable by the user and are set consistent with those used in the Home Energy Saver software suite (documented elsewhere in this Wiki).The Scoring Tool provides an asset calculation and thus has limited application for informing home occupants how to optimally operate their home. For that reason any Scoring Tool session input may be automatically imported into Home Energy Saver (hes.lbl.gov) or Home Energy Saver Pro (hespro.lbl.gov) -- feature coming soon. These tools allow the homeowner or contracted energy professional to consider the operational/behavioral aspects of the home as well as evaluate ancillary energy-using devices (such as pools, wells, second refrigerators) that are not included in the standardized asset score.
To most fully reflect the value of asset-based upgrades, scores are computed based on the energy use associated with those features (essentially heating, cooling, and water-heating).
The Department took into account many different factors as well as available sources of data in an effort to develop a scoring system that could fairly compare the energy performance of existing homes. The Department sought to develop a simple system that allows consumers to understand how a home compares to other homes regardless of location and weather patterns. The current methodology is applicable to single-family homes and townhouses in the continental US and Hawaii.
The tool scores a home on a 10-point scale, where a 10 corresponds to greatest efficiency (minimal energy use). Each point on the scale corresponds to a specific source BTU level. National average source energy factors were used to calculate a total energy value for electricity, natural gas, liquified propane gas and distillate fuel oil energy sources delivered to the home. The source energy factors are from the Energy Star Portfolio Manager Technical Reference (US EPA, 2013).
Also in keeping with the asset-based methodology, a consistent set of upgrade recommendations must be considered for each home (variations in which are recommended as a function of home characteristics, cost-effectiveness, etc.). Upgrades considered in the Scoring Tool include improvements to the home envelope and major equipment (the "assets"), but not to upgrades of lighting and appliances or usage changes. Unlike the other Home Energy Saver tools, the Scoring Tool applies a fixed, standardized retrofit cost (from the NREL National Residential Efficiency Measures Database) and generates recommendations providing the highest performance level with a payback time of 10 years or less. Energy savings are those achieved by moving between the baseline home and the level of the deemed efficiency level of the upgrade. General information on "non-asset" upgrades is provided in a "Tips" sheet, attached to the Home Energy Score Label.
The following two categories and specific upgrades are currently provided by
Type 1 - Improvements recommended now - These upgrades can help you save energy right away
Type 2 - Recommendations for when you need to replace equipment – These recommendations will help you save energy when its time to replace or upgrade.
It is important to note that the sum of the savings from the individual measures of the recommendations report may not equal the total savings for the package of selected upgrades (the number shown on the label). This difference is due to interactive effects of individual energy improvements. When improvements reduce energy consumption within the same end-use (e.g., a window upgrade plus an air conditioner upgrade), the resulting dollar savings is less than the sum of the savings shown for the individual improvements.