Building Energy Asset Score Program Overview and Technical Protocol

PNNL-22045 Rev. 1.2 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Building Energy Asset Score Program Overview and Technical Protocol (Version 1.2) N Wang S Goel V Srivastava A Makhmalbaf September 2015 PNNL-22045 Rev. 1.2 Building Energy Asset Score Program Overview and Technical Protocol (Version 1.2) N Wang S Goel V Srivastava A Makhmalbaf September 2015 Prepared for the U.S. Department of Energy under Contract DE-AC05-76RL01830 Pacific Northwest National Laboratory Richland, Washington 99352 Summary The U.S. Department of Energy (DOE) is developing a voluntary national scoring system for commercial and multi-family residential buildings to help building owners and managers assess a building’s energy-related systems independent of operations. The goal of the score is to encourage cost- effective investment in energy efficiency improvements for these types of buildings. The system, known as the Building Energy Asset Score, will allow building owners and managers to compare their building infrastructure against peers and track energy efficiency impacts of building upgrades over time. The system will also help other building stakeholders (e.g., building investors, tenants, financiers, and appraisers) understand the relative efficiency of different buildings in a way that is independent from operations and occupancy. Prior to developing the Asset Score, DOE performed a market study1 to ensure that the effort would help address market needs and fill identified gaps. In 2012, DOE began initial pilot testing of the Asset Score. In 2013, DOE continued to assess the Asset Score through additional pilot testing and a variety of technical evaluations and performance analyses. Those efforts improved the tool, training materials, and other aspects of the program. Over 200 buildings were scored and analyzed, as of the end of the 2013 pilot. Results from these efforts were released through a public webinar.2 This report outlines the technical protocol used to generate the Asset Score, explains the scoring methodology, and provides additional details regarding the Asset Scoring Tool. This report will be updated periodically to reflect changes to the scoring methodology, the Asset Scoring Tool, and other aspects of the program. The alternative methods that were considered prior to developing the current approach are described in the Program Overview and Technical Protocol Version 1.03 and Version 1.1.4 Asset Score The Asset Score enables building owners and managers to evaluate the as-built physical characteristics of buildings contributing to their overall energy efficiency, independent of occupancy and operational choices. The physical characteristics evaluated include the building envelope, the mechanical and electrical systems, and other major energy-using equipment, such as commercial refrigeration. The Asset Score is generated by simulating building performance under a standard set of typical operating and occupancy conditions. By focusing only on buildings’ physical characteristics and removing occupancy and operational variations, the system allows “apples-to-apples” comparisons between differently operated buildings (see Table S.1). 1 McCabe MJ and N Wang. 2012. Commercial Building Energy Asset Rating Program – Market Research. PNNL- 12310, Pacific Northwest National Laboratory, Richland, WA. 2 http://energy.gov/eere/buildings/commercial-building-energy-asset-score-2013-pilot 3 Wang N and WJ Gorrissen. 2012. Commercial Building Energy Asset Score System: Program Overview and Technical Protocol (Version 1.0). PNNL-22045, Pacific Northwest National Laboratory, Richland, WA. 4 Wang N, S Goel, and A Makhmalbaf. 2013. Commercial Building Energy Asset Score System: Program Overview and Technical Protocol (Version 1.1). PNNL-22045, Pacific Northwest National Laboratory, Richland, WA. iii Table S.1. Scope of Asset Score. Included in Asset Score Does NOT Affect Asset Score General Building geometry and orientation Building surroundings (such as shading from trees or other buildings) Window orientation, window-to-wall ratio External shading devices (overhangs, vertical fins) Internal shading devices such as curtains, blinds Thermal performance of building envelope (walls, windows, roof, and floor) Main heating, ventilating, and air-conditioning Back-up systems, efficiency degradation related to age (HVAC) systems (types and efficiencies) and maintenance, system oversize Service hot water system (type and efficiency) Lighting systems (types and numbers) Percentage of lighting controlled by sensors (occupancy Settings of sensors and controls sensors and daylighting controllers) Specific (example only) Refrigeration in grocery stores (types, number Refrigerators in office buildings efficiencies) Commercial kitchen appliances and ventilation systems Kitchen appliances in office buildings in restaurants (types, number, efficiencies) Computer servers in data centers (IT equipment power) Small server closet in office buildings Operating Assumptions Typical operating hours for each building type Actual operating hours Standard indoor air thermostat settings Actual indoor air thermostat settings Typical occupancy density for each building type Actual number of occupants Typical plug loads for each building type Actual plug loads The Asset Score uses modeled source energy use intensity (EUI) as the primary metric to generate the Asset Score, for the following reasons: • A source energy metric reduces the likelihood that one energy fuel type will be unintentionally penalized or favored over another. • Source energy more accurately gauges the global impact of energy consumption, taking into account the impact of the energy supply chain rather than only looking at what occurs at the building level. • Source energy is more closely correlated with energy cost, and so is more likely to drive investment decisions. • A source energy metric is aligned with the ENERGY STAR Portfolio Manager. As complementary information, site energy is also calculated and shown as part of the Asset Score Report. The modeled source EUI is used to generate a building’s Asset Score. Each building type has an associated 10-point technical scale (not a statistical scale). The calculated EUI is placed on a fixed scale for each building type and no baseline building is needed for the score calculation. The energy asset scoring scale is intended to reflect the current variability within the commercial and multi-family residential building stock and allows for energy efficiency improvements to all buildings from inefficient to high-performance. The scale development and scoring methodology are discussed in detail in this protocol report. iv Asset Scoring Tool The Asset Scoring Tool is a web-based evaluation tool. The tool is built on a centralized modeling engine to reduce the implementation cost for the users and increase standardization compared with an approach that requires users to build their own energy models. A centralized modeling approach lessens the user’s ability to tailor a model to a unique design feature because the levels of the input details are limited to accommodate the most common building types and characteristics. With this tool, users can enter building information online to obtain a standard Asset Score Report and feedback on areas and options for energy efficiency improvements. The Asset Scoring Tool integrates a simplified data collection method with full-scale energy modeling through an input generator, which estimates building parameters not entered by users. Given this approach, the tool reduces the time and expertise required to model a building accurately while supporting variable and complex commercial and multi-family residential buildings. The approach is designed to provide preliminary analysis, directing further effort and investment to where it can be most effectively applied. The protocol documented in this report describes the energy modeling and tool development methodologies. To generate an Asset Score, the user must provide a minimum number of necessary data inputs. Users are encouraged to provide additional building characteristics if available. To minimize data requirements, the Asset Scoring Tool applies inferred values to any unrequired building fields not specified by the user. Along with the building’s current Asset Score, the Asset Scoring Tool identifies areas for building improvement and estimates their potential for improving the Asset Score. Users who do not have access to the minimum required data can use a Preview version of the tool that relies on a much greater number of defaults to generate a model. This version provides a limited assessment of the building but does not provide an Asset Score. The Asset Scoring Tool is not intended to replace a more comprehensive energy audit or engineering analysis needed to properly identify and design building system upgrades; rather, it is meant to provide building owners and operators with a quick, low-cost, standardized way to rate building energy assets through a consistent, national program. DOE expects that all scores—whether simple or advanced— would be considered preliminary until validated by a qualified professional. Real estate transactions would likely require the validated advanced score. Requirements for validation have not yet been developed. Asset Score Report The Asset Scoring Tool produces a standard Asset Score Report that includes four sections: • Asset Score. The report provides a building’s current score and potential score based on

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