Step 3: Identify Data Needs

Standard Data Sets Developed by BPI WG-5

When exporting or importing data with third-party data systems, it is important to develop a concise set of data requirements. As stated above, the BPI data standards are capable of describing and transferring a large universe of data, only a portion of which is needed for any one use case. To facilitate efficiencies between programs, BPI is in the process of developing standard data sets, each of which is associated with a specific use case. Use cases (defined here as a set of interactions designed to achieve a specific function within an energy efficiency program) that BPI WG-5 has identified as particularly important for energy-efficiency programs include:

1. Reporting on the baseline conditions of a home and proposed improvements
2. Reporting on the improvements to the home compared to baseline conditions
3. Reporting on health and safety testing
4. Reviewing a contractor’s work as part of a QA process
5. Reporting a home’s energy efficiency assets to the parties in real estate transactions
6. Reporting data on program activity to DOE and other agencies

The standard audit and upgrade data sets are data collection and transfer requirements that were created by existing HPXML adopters to facilitate the transfer of project data from third-party energy modeling tools to a program management database. As a collaboration between Home Performance with ENERGY STAR programs in Arizona, California, New York, Vermont, and Virginia, the standard use cases are well suited for a wide range of program types, climate zones, and implementation models.

Although these standards are being developed for Home Performance with ENERGY STAR or whole house programs, they can be used by other types of programs as well, such as weatherization of single measure programs.

Even if implementation is not for a whole home program, these use cases are still a great place to start, as several software vendors are already able to transfer the data required in these use cases. Any subset of data within these use cases will be easy to implement for existing HPXML-compliant tools.

Standard use cases also represent the required fields that implementation partners have agreed to transfer to date. These data points have been identified by the BPI WG-5 as sufficient and achievable as data collection requirements for third-party energy modeling tools. The BPI data standards support the collection and transfer of additional data points beyond these use cases. However, additional data may require software vendors to make substantive changes to their software. Program administrators should recognize the financial impacts of custom data collection requests and consider providing financial assistance to software vendors to meet any customization requests, as appropriate.

Before reviewing the standard use cases, there are several best practices to consider.

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Data Selection Best Practices

Be Transparent with Stakeholders

Transparency with your contractors and software vendors throughout the process will help guide programmatic decisions and prevent challenges down the road. This is particularly true for the data selection process as stakeholders can bring attention to potential challenges that need resolution. For example, a program may request a specific data point that is not typically collected by most software products. If vendors can identify this need early on, a resolution can be reached in the planning phase and not delay the project later on.

Be Sensitive to Data Collection Burden

When selecting data requirements, programs should collect just enough data for program compliance and measurement and verification of results. As a guiding principle, Home Performance with ENERGY STAR recommends that programs employ administrative procedures that minimize the burden of participation for contractors and homeowners. When choosing what data points are mandatory for your programs, it is important to recognize that every data point collected has a cost to contractors to collect. Collaborate with evaluators, contractors and software vendors to explore solutions that meet the need of the program as cost efficiently as possible.

Leverage data choices made by other Program Administrators

HPXML is easily extensible and therefore can be customized to the specific needs of a program. That said, program administrator should look at the data sets being implemented by other programs around the country as many software company are already exporting and importing these standard data sets. When a program is using unique data requirements, the associated customization can push significant development costs for that specific program onto other parties, like software tool vendors and service providers. To streamline implementation and best leverage efforts from other programs it is encouraged to coordinate with other program administrators to minimize the number of program-specific data fields required in your jurisdiction. This guide provides a HPXML data selection tool below to easily facilitate this coordination.

Schedule Updates to Data Requirements

Software developers tend to work in phases to control releases of their software. To avoid additional costs or confusion, try scheduling regular updates once or twice a year and communicate future changes as early as possible. This will help with version control and create more manageable process for software vendors and your implementation team.

Adopting these best practices will assist in establishing a streamlined data selection process.

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HPXML Data Selection Tool

To assist program administrators in reviewing the standard use cases that are being implemented by other programs, a data selection tool is available to help identify what data points are currently required in these use cases and helps programs select and communicate the requirements for the program. The HPXML Data Selection Tool is a “living document”, so if a programs identifies data points that are not in the use cases, WG-5 can assist in added them to the tool and thus meet the program’s needs.

• Download: HPXML Data Selection Tool (EXCEL, 838 KB)

The attached instructional video will provide a walkthrough of the HPXML data selection tool. Using the tool programs can quickly select the data required for HPXML program implementation. Programs can then forward the tool to the implementation team, trade allies and software providers, giving them clear guidance on the requirements for HPXML Implementation with your program.

Additional details about the data structure and standard data sets are provided in the sections below.

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Understanding the HPXML Data Structure

In the reviewing tool, notice the following descriptors for each data point:

• Data Category
• A general description of the information at the building characteristic or contact information level. Note: Insulation has several data categories, depending on the insulating plane. For example, referencing insulation installed on the attic floor “Attic Floor Insulation” or on the bottom of the roof deck “Attic Roof Insulation.”
• Data Element
• A specific data point or descriptor within that data category. For example, insulation material type or R-value.
• Data Type
• How the data should be provided. For example, as a number, text, enumeration, etc.
• Definition
• A written description of the data point and what it means. As the name of the data point is not always clear, this provides a narrative explanation of what each data point describes.

In most cases, there are several data points needed to describe any one building characteristic. For example, if you require blower door testing in your program, you will require “Air Infiltration” information. In this case, there are three data points that are required to describe an air leakage measurement, such as 2000 CFM₅₀:

“Building Air Leakage” = 2000

“Building Air Leakage Unit” = CFM

“House Pressure” = 50

This also provides flexibility to receive the same data in multiple formats. For example, air leakage could be represented in CFM50, ACH or ACH50.

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Setting the Program’s Data Requirement Level

The program administrator’s main task in this step is to determine the data element “requirement level.” This sets the minimum requirements for software tools to participate in your program. In each of the use cases, there are two requirement levels:

• Required
• All software must collect this data point and transfer it any time it exists in a home. This usually is driven by rebate qualifications or quality assurance requirements.
• Optional
• Not required.

The HPXML Data Selection Tool will allow you to see the minimum required fields that have been agreed upon by BPI WG-5 for audit and retrofit use cases. In addition, you can use the Home Energy Score and BPI — 2101 requirement toggles. By activating these toggles, you can see which fields would be required if you wanted to complete a Home Energy Score or to fill out a BPI-2101 Home Performance Certificate of Completion.

The grayed out fields are optional and represent fields that are relevant in many programs, but not required in the standard use cases. You can choose to make optional fields required in your program. However, not all software products on the market collect every possible data point. Making some of these data points “required” may restrict which products are eligible to participate, or may require you to pay software vendors to code their software for this requirement. Communication with potential software vendors is key and consider their feedback on which fields you require for your program before determining your final data requirements. BPI WG-5 can help facilitate that conversation in a constructive environment.

Some programs with a large number of measure-specific rebates are choosing to identify data points as “optional” to allow flexibility in implementation. Your program can use a minimum data collection standard that is required for every home. However, if the contractor or software vendor wants to participate in the full spectrum of rebates, they can choose to send “optional” fields that trigger a rebate payment. This allows a diverse set of software products and contractor business models to participate, without mandating that every software and contractor support the full spectrum of rebates your program portfolio may offer. If you want to choose this path, it will be important to provide clear specifications on which “optional” fields will trigger which rebate payments.

Defining Use Cases

The standard use cases provided as a part of this guide are the primary use cases that have been developed to date. Each use case only uses a fraction of the data points that the HPXML standard can support. Over time, more use cases will be developed to meet market needs.

Audit Use Case

The audit use case is designed for Home Performance with ENERGY STAR or whole house programs that require energy assessments. This use case allows auditors to submit their audit results and proposed scope of work for an eligibility review from the program. Required fields are established to help identify the home’s existing characteristics, health and safety needs, recommended improvements, and associated savings predictions.

An example of an audit use case HPXML file can be found on the HPXML GitHub repository and more technical description of the audit and upgrade use case can be found in the software developer guide at Audit-Upgrade.

Upgrade Use Case

The upgrade use case is designed to facilitate the transfer of completed whole house upgrade projects, such as Home Performance with ENERGY STAR or Weatherization programs. This includes the pre-upgrade condition of the home and a description of the installed measures, as well as associated predicted savings. Required fields are established to complete a full quality assurance review of all installed measures and determine rebate or financing eligibility. The minimum requirements reflect those most common between all of the HPXML-compliant programs so far. Programs that offer more diverse rebates may need to consider changing “optional” fields to “required” in order to meet program needs.

The upgrade use case HPXML file is very similar to the audit use case. The differences are detailed in Audit-Upgrade.

Home Energy Score Use Case

The Home Energy Score use case defines the minimum data set required by the DOE’s Home Energy Score tool, in order to properly generate the 1 to 10 score. These data point are clearly identified in the data selection tool. Programs interested in generating a Home Energy Score, will need to make sure that their HPXML software tool are collecting this minimum dataset.

In order to generate the score, your program software team will also need to integrate with the DOE’s Home Energy Score API. HPXML can be transferred through the API and generate a Home Energy Score in real time. For more information on integration with the Home Energy Score API, see Home Energy Score in the software developer guide.

A full list of HPXML data elements that can currently be incorporated into use cases is available in the online schema documentation.

BPI — 2101 Certificate of Completion Use Case

The Certificate of Completion use case is designed to ensure that the value of energy efficiency improvements is visible in the real estate transaction. Studies suggest that buyers will pay higher prices for efficient homes — but only if they know that the homes are efficient. Programs have traditionally had difficulty in getting information about energy efficiency improvements into the real estate transaction. The Certificate of Completion use case provides a standardized framework for programs to collect and assemble data about a home that features energy efficiency improvements ranging from a single installation to a whole-house upgrade. The standard data set in this use case is aligned with both the Appraisal Institute’s Green and Energy Efficient Addendum and the Real Estate Transaction Standard, allowing data from a trusted third party (a Home Performance with ENERGY STAR or other efficiency program) to flow seamlessly to appraisers and real estate (MLS) databases.

Note: The BPI — 2101 Certificate of Completion Use Case is designed to be highly flexible and inclusive of a wide range of technologies. When implementing this use case, most contractors and software vendors will not support the full spectrum of technology to import to your program. However being able to capture the full spectrum of data point and export to other third parties, will give your program the widest range of options for interacting with the real estate industry.

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How to Add Data Elements

When reviewing the data sets that are required for your implementation, it is possible to identify a data point you require that is not in one of the pre-defined use cases or the HPXML standards. If this is the case, BPI WG-5 can assist in adding the new data element and in identifying how to incorporate it into the standard. In some cases this might include adding new elements to the standard to account for data points that could be applicable across many programs. However, if the data point is truly unique to your program, WG-5 has also introduced “measure codes” that allow a code to be assigned for a specific measure in a specific program. This creates added flexibility without needing to modify the standards in all cases.

To submit a new data element for consideration, you can use the WG-5 GitHub account. This way all members can see your recommendations and address them immediately. Follow the steps below to submit additional requests if needed:

1. Sign up for a user account on GitHub.
2. Go to the HPXML GitHub issues page.
3. Click “New Issue”
4. Fill out the form to ask a question or make a request. No need to assign a person, milestone, or label.
5. Click “Submit New Issue”.

Once you have defined the use case needed for your program and have identified all required fields, you are ready to proceed to the next step. Remember, this can be an iterative process. It is good to do due diligence in the planning process. However, even the best implementation plans may need to be modified as the program goes to market and a large number of homes start running through it.

Note: Schedule opportunities later in your implementation to check in on data requirements and adjust as needed.

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