Energy Asset Score Frequently Asked Questions
The U.S. Department of Energy (DOE) has received a set of questions in response to the request for information (RFI) published on August 8, 2011, and a series of stakeholder outreach activities including webinars, a workshop, and focus group meetings. These queries from participating building owners and operators, realtors, municipalities, and others focused on the scope of the asset score program, target audiences, scoring methodology, quality assurance, and the potential for additional supported options.
Frequently asked questions regarding the commercial building energy asset score program are available below and are listed by the following categories:
- Program Overview
- Basic Metrics
- Target Audience and Building Types
- Scoring Methods
- Scoring Scales
- Identified Opportunities for Energy Efficiency Improvements
- Potential for Additional Supported Options
Q: What is the commercial building energy asset scoring system envisioned by DOE?
A: DOE is establishing a national standard for a voluntary energy asset score system, which includes a tool that can help building owners evaluate their buildings with respect to this standard. Based on the centralized energy-modeling tool, the asset score program evaluates the physical characteristics of the building "as built" and its overall energy efficiency independent of its occupancy and operational choices. The model takes into account the building envelope, the mechanical and electrical systems, and other major energy-using equipment that are actually built into the building. The asset score system identifies potential opportunities for efficiency improvements and note what impact those opportunities might have on the potential asset score of a building.
Q: What is DOE's objective in creating an energy asset score?
A: DOE's goal in undertaking a national building asset score is to facilitate cost-effective investment and energy efficiency in commercial buildings by providing a tool that allows building owners to benchmark their buildings against peers and other market players to understand the relative efficiency of different buildings in a way that is distinct from building operations and occupancy. The asset score system provides a centralized modeling tool that both reduces the implementation cost and increases the standardization compared with an approach that requires users to build their own energy models. In other words, building owners do not need to hire an expert energy modeler to perform a preliminary energy analysis and obtain an asset score. The asset score tool will provide value in the first step of assessing a building by identifying some possible upgrade opportunities. The asset score system is not intended to be a replacement for a full energy audit of a building.
Q: Do you anticipate the Asset Score becoming mandatory?
A: The asset score program is being developed by DOE as a voluntary program.
Q: Was there enough time to adequately consider and address all stakeholder comments?
A: DOE published a Request for Information (RFI) on August 08, 2011 and conducted a series of webinars, interviews, and focus group studies to collect market feedback. A workshop was held in Washington, D.C., on December 8 and 9, 2011, to further engage stakeholders in the program design. The asset score program has defined reasonable goals and criteria to evaluate the quality of the product in each development phase. All project documents are publicly available. DOE launched the first pilot project in spring 2012 and further tested the asset score system and tool with a diversity of commercial buildings. DOE will continue the pilot project in 2013. The second RFI will also be published in fall 2012.
Q: How is the asset score program different from ENERGY STAR® Portfolio Manager?
A: Although both ENERGY STAR® Portfolio Manager and the DOE asset score program provide building energy efficiency scores, the focuses are different. Portfolio Manager reflects the overall building performance resulting from the building efficiency and its operation and maintenance. The purpose of an asset score is to break out the infrastructure piece so that building stakeholders can consider the as-built efficiency and operational practices separately. The asset score takes into account only the physical assets of the building and enables building owners and operators to separate out the operational aspects. This allows the comparison of building assets on an equal footing by eliminating the wide variation due to differences in operation and maintenance, plug loads, and occupant behavior. Building stakeholders can then determine whether a building is performing well because it is a high-efficiency building or because it is well managed. The asset score tool provides more granular information, enabling building owners to target limited resources toward those areas that will produce the most efficiency improvements.
Q: How does DOE envision the commercial building energy asset score working with ENERGY STAR Portfolio Manager?
A: The asset score program is intended to be complementary to Portfolio Manager. Portfolio Manager compares an existing building to its peers through an analysis of that building's energy bills and operational characteristics. In any given building, a number of factors influence energy use and the outcomes measured by the energy bill. The asset score will help segregate some of these factors—those related to the physical infrastructure of the building. The ability to see these factors in isolation enables building stakeholders to better determine whether higher-than-expected energy use is due to inefficient physical infrastructure and specific building systems or to occupancy, operations, or other factors.
Q: What's the target cost for an owner to get scored?
A: The asset score tool is free for users. The only cost for a building owner will be verified data collection and input. DOE is evaluating existing credential programs that can support asset score data verification. During the pilot project, cost information will be gathered.
Q: What metrics is used to determine the score?
A: Source energy use intensity (EUI) is the primary metric with which to generate the asset scores. Other metrics, such as site energy use, are separated out by fuel types, energy cost, and system-level performance indicators are included in the asset score report to provide additional ways to evaluate building efficiency.
Q: Is greenhouse gas emission reflected on the score?
A: Greenhouse gas is not used as the main metric to score the building. It may be included as optional content in the future.
Q: Is cost information provided? If so, what cost metric is used?
A: Estimated annual building energy costs and savings, based on average regional utility rates, are provided in the asset score report. However, cost is not used as the main metric to score the building. The estimate of energy costs and savings cannot be compared directly with the utility bills for a building because they are based on the assumptions that the building is fully occupied, operated for a certain number of hours per week (typical operating hours for the building type), and has standard miscellaneous loads—for example, numbers of computers and numbers of vending machines. The estimated annual energy costs based on standard conditions provide an apples-to-apples comparison between buildings.
Q: Does the score system compute the asset score with or without on-site renewable energy systems?
A: Currently, the asset score tool does not include the on-site renewable energy generation in the EUI calculation because energy efficiency is the focus of this program. DOE is evaluating different means to address on-site renewable energy generation and will include it in the asset score tool in the future.
Q: Does the asset score include information on water use or other green building features?
A: Energy is the current focus of the DOE asset score. Water use is not included.
Target Audience and Building Types
Q: Is the asset score tool free and accessible to the public?
A: Yes, DOE provides the asset score tool, a Web-based application, free of charge. Any user can set up an account, enter the building information, and obtain a report of preliminary analysis. However, to obtain a verified asset score, a qualified professional is needed to validate the information entered into the asset score tool. The credential of a qualified professional is still under development.
Q: What building types are covered by this scoring scheme?
A: The rollout of the program has been organized in a phased approach, focusing first on building types that are simplest to understand and about which we have more information to establish a scoring system. Phase I, which will be included in the initial rollout, includes office, educational, retail, and unrefrigerated warehouse buildings. Phase II includes lodging, food service, food sales, public safety, religious worship, and mixed-use types of buildings that incorporate Phase I and II uses. Phase III buildings are either those with more complex systems or those for which we currently have a limited body of information, such as data centers, laboratories, refrigerated warehouses, health-care facilities, public assemblies, and so on. DOE is also rolling out a residential asset score system, and it remains to be determined what type of multi-family residential buildings will be included in the residential asset score system or in the commercial building energy asset score system. Both new construction and existing space are supported by the commercial building energy asset score system.
Q: Will the model be expanded to include other building types as it progresses?
A: Yes, the asset score system is intended to include most types of commercial buildings. Additional building types will be added as the program develops.
Q: Is there a need to separate building types into so many phases? Won't most buildings essentially have the same types of assets?
A: To ensure a fair scoring and comparison, it is necessary to evaluate buildings by use type. A main reason is that the assumed standard operations are different. For example, schools have operating schedules and miscellaneous plug loads that are very different from those of retail establishments.
Q: Are there plans for including more detailed space subtypes? There are many different kinds of office space (for example, regular office, trading floors).
A: Not at this time, although if sufficient data exist to make detailed calculations about internal loads and operation patterns, then space subtypes could be addressed in the future.
Q: Is there a minimum size threshold for buildings that can be scored?
A: No. The goal is to make the building energy asset score system equally applicable to small and large commercial buildings.
Q: Does asset score apply to both new and existing buildings?
A: Asset score is equally applicable to both new and existing buildings. For new buildings, a design team could upload the inputs from their design parameters into the tool and receive both a score and recommendations to make the design more energy-efficient. The process would be the same for an existing building, except that the installed systems should be used instead of the designed systems.
Q: What information will be available for the public and what will be kept confidential?
A: A user of the asset score tool may choose to make the results available to third parties. DOE has no intention at this time of disclosing to a third party any information entered into the asset score tool that can be used to identify a building and its design features without the consent of the owner of that information. DOE may use statistical information about large numbers of buildings in a way that does not allow third parties to identify individual buildings.
Q: Are there varied levels of data user access?
A: The asset score tool has two levels of user access. Any user can obtain a preliminary asset score report. A qualified assessor can generate a verified report for official purposes. The tool can potentially provide different levels of data access.
Q: What components are included in the score?
A: The asset score includes physical characteristics of the building as built and its overall energy efficiency, independent of occupancy and operational choices. The physical characteristics include the building envelope, the mechanical and electrical systems, and other major energy-using equipment (for example, commercial refrigerators). Miscellaneous loads (for example, office equipment and appliances) vary with building occupancy and are therefore standardized in the asset score by building type. Installed controls such as daylighting controls and occupancy sensors, variable-frequency drives, and variable air volume terminal units are included in the asset score. However, the control schemes of these systems are not specifically modeled because they are based on building operational choices.
Q: Is there an added distinction in the model to ensure a fair scoring for new construction and existing buildings? What about historic buildings?
A: All buildings are scored using the same method. However, different reference points are provided for buildings of different vintages in different climate zones. For example, the reference point for a 50-year old medium-size office building in Chicago is the average energy use of medium-size office building built prior to 1980 in a cold and humid climate. In addition, the model calculates a potential score that incorporates the cost-effective upgrade package and considers the limitations of different construction methods. A historic building with limited potential due to its preservation requirements can be properly addressed this way. In other words, a historic building with a specific envelope type will have limited envelope upgrade options and therefore may have a lower potential score.
Q: Are new and old buildings scored differently?
A: To ensure accuracy and consistency, buildings constructed in different years are scored in the same way.
Q: Does the asset score tool account for the year that equipment is installed and for performance degradation?
A: The asset score tool accounts for the year that equipment is installed when estimating the equipment efficiency. The performance degradation is not considered because it is affected by maintenance and many other factors.
Q: Does the asset score tool account for different occupancies, building additions, and renovations?
A: The occupancy is standard (fully occupied with normal operating hours); building additions and renovations are included in the score.
Q: Does the asset score tool use a standard set of operating conditions? What are those standard operating conditions?
A: Yes, the scored building is modeled using a standard set of operating conditions. DOE uses recognized standards such as those defined by Commercial Energy Services Network (COMNET) and American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).
Q: How is building location assessed? Does the energy model normalize weather?
A: A building falls into a specific weather location. The model uses normal weather conditions in modeling a building's projected energy use. The scoring system normalizes a building's score to account for climatic differences.
Q: What is the basis of the software that is being used to model the building? What simulation guidelines and procedures might be proposed for the asset score program?
A: The asset score tool uses EnergyPlus as the centralized energy modeling engine; however, tool users do not need to interact directly with EnergyPlus. Users enter a limited set of building data into an intuitive user interface and obtain the asset score report through the Web-based tool. Therefore, no specific modeling guidance is necessary. Data collection guidance will be provided, and documentation of modeling methodology will be publicly available.
Q: Does the Web-based asset score tool perform building simulations in real time, or does it look up pre-simulated values?
A: The Web-based asset score tool runs real-time simulations.
Q: What is the minimum building level data necessary for the asset score tool to be sufficiently robust?
A: DOE is currently evaluating the level of data necessary to provide meaningful results that is cost-effective from both a modeling standpoint for the scoring system and an information-gathering data input perspective for building owners. There are two levels of data input, simple and verified. Simple level data collection requires minimum data input and relies on an inference engine to generate the energy model and provide preliminary analysis. Verified level data collection requires more data, with which users can receive a more accurate analysis and official asset score and report.
Q: Has DOE developed a detailed list of what building data need to be collected and what inputs are provided in the Web-based tool?
A: A preliminary data collection list has been developed. DOE is still finalizing the list to ensure the information collected enables a robust analysis while maintaining a reasonable level of data collection. DOE is using a pilot test of the program to evaluate the data collection protocol.
Q: What scale is DOE using?
A: After evaluating various ways to construct a scale on which to place the score, DOE has chosen to use a technical scale that directly converts kBtu/ft2 into 1 to 100 points, and that is not population-weighted as is a statistical scale.
Q: What are the two extremes of the 100-point scale?
A: Zero energy is used as one extreme (100 point) of the scale to develop a fixed goal. The other extreme (1 point) of the scale varies by building types. It corresponds to the performance of low-efficiency buildings based on the energy use of the current commercial building stock.
Q: Is there a reference point such as a baseline building?
A: No baseline building is needed to calculate the asset score because a candidate building is evaluated using a pre-defined fixed scale. The average energy use of a specific building type in a specific location is provided as a reference point to help stakeholders understand how a building is compared with similar buildings in the region. However, this reference point does not affect the candidate building's score.
Q: Is the Commercial Buildings Energy Consumption Survey (CBECS) used as a baseline for the scoring scale?
A: Asset scoring is independent of the CBECS data because it evaluates a building on its own merits rather than against a population of other buildings. DOE uses CBECS and other building databases only to ensure that the developed scoring scale can truly reflect the efficiency distribution of current building stock. Both high-efficiency and low-efficiency buildings should be effectively evaluated.
Q: Will the scoring adjust over time or with technological advances?
A: DOE intends to use a scoring system that allows a building to maintain its score for at least 10 years if the building is maintained and does not undergo significant infrastructure changes. A building score will be changed only if an energy efficiency upgrade is implemented.
Q: How does the model deal with mixed-use properties? For example, server rooms or trading floors as part of an overall office building?
A: Mixed-use types of buildings that incorporate Phase I and Phase II use types will be included in the Phase II rollout. Those with either more complex systems or those for which we currently have a limited body of information (such as data centers, laboratories, refrigerated warehouses, and health-care facilities) will be included in the Phase III rollout. The different uses are divided on the basis of square footage, and a weighted average EUI for the entire building is generated and scored.
Q: Is there a method to provide a system-level scoring?
A: The asset rating tool provides both a whole-building score and system-level evaluations for lighting, cooling, heating systems, building envelope, and service hot water systems.
Q: Can the EUI (kBtu/ft2) value provided by the asset score tool be directly compared to the EUI number derived from ENERGY STAR Portfolio Manager?
A: The EUI provided by the asset score tool is modeled energy use under a standard operating condition; the EUI derived from Portfolio Manager is measured energy use under a specific operating condition. Therefore, these energy use intensity values are not directly comparable. DOE is working with EPA to develop means to help building stakeholders effectively use the information from the asset score tool and Portfolio Manager and make meaningful and consistent comparisons.
Identified Opportunities for Energy Efficiency Improvements
Q: How are the recommendations determined for energy efficiency measures (EEMs)?
A: Potential EEMs are considered iteratively—alone and in combination—to develop a cost-effective package of potential measures. Interactive effects between measures are considered. Only those EEMs found to be life-cycle cost-effective as defined in the government standard building life-cycle cost approach will be suggested to a user.
Q: How does the asset score tool ensure the recommendations provide useful guidance and keep up with technological advances?
A: The asset score tool considers the limitations of the existing building construction, accounts for the system performance depreciation over time, and performs life-cycle cost analysis. All these capabilities help ensure that the identified opportunities are practical. The modeling tool and EEM library will be maintained to keep up with the technological advances. The update of the EEM library may affect the results of the EEM recommendations, but does not change a building's asset score.
Q: What information is included in the asset score report?
A: The following information is included in the asset score report:
- Basic building information, including property address, year built, climate zone, building type, year score report issued
- Source energy use intensity and the corresponding score
- The potential source energy use and score that could be achieved if the building makes identified upgrades
- The energy savings associated with that upgrade and potentially cost savings based on average energy cost
- Reference points to help users understand how their building score compares to current codes or another chosen reference point on a scale
- Energy use breakdown by system category
- System-level evaluations
- Identified improvement opportunities
- A list of building asset characteristics that are used in the energy asset tool.
Q: Is there an offset for passive design elements?
A: Passive design elements are considered on their own merit rather than specifically as a "passive element." For example, window shading is a passive feature. When analyzed in the tool, if the shading reduces the total energy consumption of a building, it will be reflected in a better building asset score. Some more complicated building geometry elements used in passive design may not be available in the first iteration of the tool.
Q: How does DOE maintain quality control for the asset score tool?
A: First, the energy modeling approach is a centralized real-time simulation. Although users will gather and enter the data to the website, the modeling itself will be standardized. Second, the asset score tool uses an established and standardized methodology for data collection to ensure consistency with other systems. The user interface includes automated checks and provides a warning if entered data appears incorrect or incomplete. Third, the asset score program will include a full range of technical support. All of the documentation for the asset score tool will be available online, allowing for transparency, and will include a complete user manual, data input checklist, and set of frequently asked questions.
Q: How to ensure accuracy and consistency of input and output?
A: DOE is considering different approaches to quality assurance, which include requiring submissions from a qualified professional in order to receive a verified score. The output is generated through a centralized modeling tool, which ensures the consistency and replicability of the results.
Q: How detailed are the input requirements?
A: The level of detail is a tradeoff between cost and accuracy. A low number of inputs minimizes the effort required to collect data. However, using a larger number of inputs can increase accuracy. DOE's objective is to find the level of detail that provides a reasonable balance between accuracy and data collection cost. The tool will contain clear and consistent definitions of the data requirements and basis of measurement. Ultimately, the asset score tool is not intended to be a replacement for a full energy audit of a building, which would entail detailed calibration, complex analysis, and onsite visits.
Q: What type of training or credentials will be required of the qualified professionals? Will third-party verification be used to issue an asset score?
A: DOE is still evaluating different credential programs. The key validation for asset score is on the data collection and input because the score is created through a centralized modeling tool. In this case, an independent third party may or may not be needed. DOE does not intend to create an entirely new credential program for asset score but will develop selecting criteria and training materials.
Potential for Additional Supported Options
Q: Will there be an ability to link the asset score tool with third-party applications?
A: Yes. The intent is for third-party applications to link with the asset score tool. DOE envisions the potential for an application programming interface (API) or other means to enable third parties to build applications that will exchange data with the asset score tool.
Q: Will users be able to upload data that has already been collected by ENERGY STAR Portfolio Manager?
A: Yes. DOE's objective is for a building owner to be able to export relevant information from one to the other.
Q: How will the asset score system respond to localized requirements and opportunities? Will there be features of the system to allow for state/local flexibility?
A: DOE recognizes that some users may wish to compare buildings to a locally-specific population of peers or to incorporate the asset score into other programs. DOE is interested in understanding these customization needs and will consider working with interested stakeholders on a case-by-case basis.
Q: Will the asset score tool allow for comparisons to local code or other user-defined reference points?
A: The asset score tool is being designed to allow for third-party applications to interface with the system. Third party applications could be developed to provide users of the tool with comparisons to local codes or other user-defined reference points.
Q: Will education and training be incorporated as part of the rollout?
A: Yes, DOE will provide education and training materials for data collection, using the asset score tool, and interpreting the asset score report.