Streamlining Multifamily Energy Upgrades

August 31, 2013
September/October 2013
A version of this article appears in the September/October 2013 issue of Home Energy Magazine.
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Multifamily buildings represent a huge untapped potential in the U.S. residential energy upgrade market. With more than 31.5 million units of existing housing across the nation, the multifamily building stock has tremendous potential for both energy and cost savings.

DOE's Weatherization Assistance Program (WAP) reduces utility bills for low-income Americans by improving the energy efficiency of their homes while ensuring their health and safety. Historically, the WAP has focused primarily on performing whole-house energy upgrades of single-family homes. However, 35% of WAP-eligible households (that is, households with an income of 200% or less of the poverty level) and 24% of all U.S. households live in multifamily housing. Given this, the WAP capitalized on the opportunity presented by the American Recovery and Reinvestment Act (ARRA) to invest significant resources in multifamily housing. The weatherization of multifamily buildings now represents well over a quarter of total WAP implementation, with over 270,000 units weatherized since 2010. Responding to requests from practitioners in the field for additional technical resources, and aligned with the WAP's legacy of innovation in home performance, a suite of technical resources are under development to facilitate multifamily energy efficiency upgrade work.

Jennifer Somers

The WAP defines multifamily housing as any dwelling that contains five or more living units that share one or more building systems. The 2009 Regional Energy Consumption Survey (RECS) data state that nationally 70–80% of all multifamily properties (five or more units) are in small buildings. The Midwest, South, and West have 87%, 84%, and 85%, respectively, of low-rise buildings as a percentage of total dwelling units, with the Northeast being the outlier at 47%. These data support what the program discovered while performing activities under ARRA. The areas of the country that had exponential growth in multifamily weatherization included the unexpected WAP grantees like Kansas, Colorado, and Nevada that support a multifamily building stock of small low-rise and garden-style apartments. Increased weatherization activities also occurred in states generally believed to have a lot of high-rise multifamily housing, including New York and other parts of the Northeast. These regional variations can affect the complexity of multifamily building systems. Recognizing the diversity of the housing stock, the WAP is developing tools and resources that address the varied systems found in both small and large multifamily buildings.

The resources developed by and used in the WAP provide a step-by-step road map to performing multifamily whole-building energy upgrades. The WAP network often describes a multifamily energy upgrade process as akin to a snake digesting a large meal. Split incentives, utility data collection, owner contributions, and funding are among a long list of potential twists and turns. It is often challenging to know how long it is going to take various bites of the meal to move through the snake's system. The WAP suite of multifamily technical resources is intended to provide practitioners with consistent and nationally supported tools to assist in moving properties through the entire process. These resources are useful to any organization seeking to perform energy efficiency upgrades in multifamily housing, irrespective of the income of the population receiving the retrofit.


Figure 1. This S-curve shows the multifamily retrofit process from site selection to postretrofit inspection.

The Multifamily Energy Upgrade Process

The multifamily energy upgrade process is complicated. Over time, the WAP has developed a multifamily retrofit process that moves a project from building selection all the way through to postretrofit inspection. Figure 1 shows the S-curve progression that the process takes. The process is long but it can be broken down into manageable steps.

The WAP benefits from the vast technical resource that is contained in the WAP network of people. Trainers, program managers, and technical and field staff provide a constant feedback loop on what's working well in the program and what needs to be improved. The insights provided through this feedback loop have led to the current comprehensive multifamily energy upgrade process implemented by the program. Nationally, the WAP's training and technical assistance focuses on standardizing the methods, tools, and approaches used in various steps of the process. Having a nationally consistent approach to completing the projects allows the entire WAP network to provide insight and innovation that can assist anyone doing the work anywhere in the country.

Data Collection and Site Assessment

When we examined the S-curve diagram shown in Figure 1, the WAP staff recognized the need for a systematic approach to gathering the data and designing the methodology needed to perform energy audits. This approach must be designed from a technical perspective. While many training resources, curricula, guidebooks, and standards currently exist that address various parts of the multifamily energy audit process, there is no nationally consistent methodology for multifamily data gathering and energy auditing. A number of standards address various elements of a multifamily energy audit, but there is currently no multifamily energy audit "standard." To help fill these gaps, the WAP is developing its "Technical Guidelines for Multifamily Building Energy Audits" The guidelines will provide both an audit procedure and technical guidance to perform the audit. The guidelines will also include pre-analysis data collection, energy benchmarking, site assessments and building systems, energy and performance modeling, ASHRAE Standard 62, and energy audit methods and policies, as well as work scope generation.

To successfully perform an energy audit and energy retrofit, it is essential to have solid, consistent data gathering and accurate building site assessments. The importance of this first step should not be underestimated. This step includes analyzing the history of the building, its construction and maintenance, its systems design, its energy use, and how the whole building operates as a system of interrelated parts. It includes preparing for a site visit, assessing the site, computer modeling, and conducting an energy audit and a postweatherization site visit analysis. These various activities ensure that the work scope is comprehensive and appropriate for the needs of the individual property.

The "Technical Guidelines for Multifamily Energy Audits" tell the energy auditor what the data-gathering and energy-auditing process should entail. However, the guidelines are not intended for the energy auditor alone. The objectives of the guidelines are to

  • provide technical guidance on site assessment activities, computer modeling, and postweatherization site visit analysis;
  • provide guidance on the development of a comprehensive work scope that meets the program's objectives;
  • provide a technical summary of current knowledge on multifamily energy audit methods and energy measures; and
  • identify current standards, research, best practices, and guidance resources important to advancing the capabilities and quality of multifamily energy audits.

The guidelines, therefore, are intended for a wide variety of audiences. These include program administrators, trainers (to integrate the guidelines into training curricula), policy developers, standards developers, and anyone working on the development of audit methods. The ultimate purpose of the guidelines are to facilitate uniformity in multifamily energy audit methods, and lead to more accurate predictions of energy and cost savings.

While the WAP has a mandate to provide cost-effective energy upgrades to clients, there has been no consistent national yardstick against which to measure performance after installation.

Data Analysis, Modeling, and Work Scope Development

With this goal in mind, practitioners in the field developed a long list of desired energy audit improvements. These included effective domestic hot water (DHW) modeling, modeling buildings with multiple heating systems, and disaggregation of end-use energy from utility bill analysis. To further define the needs of auditors in the field, energy audit methods experts as well as audit users from around the country participated in a series of feedback sessions. Based on these conversations, the WAP decided to develop the Multifamily Tool for Energy Audits (MulTEA). This investment-grade audit tool is targeted at the unique needs of multifamily buildings and includes many features not available in current tools. National experts indicated a need for better modeling of DHW systems as well as modeling of both DHW and heating/cooling distribution systems. Another identified challenge is developing standards for ventilation and indoor air quality that appropriately address the multifamily housing stock.

In addition to the improvements in modeling, the MulTEA tool has been designed to incorporate many of the tools of the trade that an experienced energy auditor possesses. Multifamily energy auditing can be as much art as science when auditors are forced to be creative in addressing certain measures. Many measures are not easily modeled using existing energy simulation methods. Over the years, auditors have developed rules-based methods for calculating energy savings that are standard formulas or calculations developed and verified through testing in the field. For example, if a building has multiple heating systems, practitioners currently need to develop ways to "trick" an energy audit tool into analyzing the building as if there were only one system in order to obtain results. These types of expert rules-based methods are incorporated into MulTEA, and it provides extended simulation capabilities to handle multiple heating or cooling systems. The issue of properly locating sensors and controls while monitoring was also identified in the needs assessment, and it is another example of the importance of rules-based savings calculation methods.

Due to the many variations in multifamily building types, as well as the challenge of incorporating different zone configurations, it is difficult to model energy use accurately. A dynamic macro structure has been developed in MulTEA using DOE 2.1E modeling that allows users to quickly create complex building shapes and unit types. Compact, box-shaped buildings with double-loaded corridors, apartments with a breezeway or open veranda, and garden-style apartments are just a few of the possible configurations. The model provides the structure to activate and deactivate floors or surfaces based on key inputs entered into the model about the building: the number of units, the number of floors, types of space, and so forth.

MulTEA is being developed in two phases to accommodate varied building systems types and complexities. The first version of the tool is for the 70–80% of users who work on less-complex buildings of four stories or less. Version 2.0 will include high-rise buildings, more-complex building systems, central plant heating and cooling systems, and more-complex weatherization measures. A major innovation planned for the tool is to allow for building energy use to be calibrated against historical weather data that prevailed during that utility billing period. The actual weather year data will be used in the true-up of the building energy simulations, which will eliminate the need to perform weather normalization of utility bills to compare them to the model results.

In summary, the MulTEA tool will

  • produce an investment-grade audit to provide auditors with an improved energy simulation and measure selection tool for multifamily buildings;
  • expand and enhance multifamily energy auditors' capabilities;
  • provide a DOE-sponsored multifamily energy audit instrument to complement the single-family and mobile-home energy audit tools already supported by the WAP and managed by Oak Ridge National Laboratory;
  • help improve the quality of multifamily energy upgrades and provide a foundation for quality assurance;
  • provide access to third-party software developers to the application programming interface or API—the calculation engine powering the tool managed by Lawrence Berkeley National Laboratory;
  • assist training providers to develop improved training materials; and
  • build confidence in energy efficiency improvements among consumers, building owners, and the energy efficiency finance community.

MulTEA will produce a recommended scope of work for a multifamily project based on a savings-investment ratio (SIR) or cost-effectiveness test. Since an audit is not complete until a scope of work is developed, the goal is to ensure that energy efficiency measures are installed that meet an SIR in rank order. The SIR is calculated using life cycle costing of the installed retrofit measures and is expressed in terms of the net present value of the retail cost of the building's fuel. The development of a final scope of work may require an iterative process (remember our S-curve) that includes educating the building owner on WAP program requirements while acknowledging available funding and the owner's areas of interest and priorities. From the final scope of work, the project will move into the actual installation of energy efficiency measures.

The SWS bring together 30 years of building science expertise from within the WAP and the greater home performance industry.

Measure Installation: The Standard Work Specifications for Multifamily Energy Upgrades

Achieving the predicted energy and cost savings from our multifamily energy modeling requires that the measures be installed as intended. While the WAP has a mandate to provide cost-effective energy upgrade services to its clients, historically, there has been no consistent national yardstick against which to measure the measure's performance following installation. The Standard Work Specifications (SWS) for Multifamily Energy Upgrades define the minimum requirements to ensure that the work performed during energy upgrades is effective, durable, and safe. The SWS define what a properly installed energy efficiency measure looks like.

A multifamily energy upgrade is, at its core, a collection of individual measures, such as replacing a boiler or air sealing the building envelope. The SWS identify the desired outcomes of specific tasks undertaken by a weatherization or home energy upgrade professional. The SWS define the outcomes, stated as objectives, and list the minimum specifications necessary for properly installed energy efficiency improvements to achieve those outcomes. The goal of the SWS is to help ensure that energy efficiency measures are installed correctly and as intended.

The SWS are a part of the "Guidelines for Home Energy Professionals" project, a collaborative effort to engage the home performance industry in developing a suite of resources that include work quality specifications, training program accreditation, and job task analyses for workers. The WAP, together with the National Renewable Energy Laboratory (NREL) and the Association for Energy Affordability (AEA), convened weatherization technical staff, trainers, and program managers, together with other home performance, worker, and health and safety experts, to develop the Multifamily SWS. This national reach, diversity of subject matter experts, and laying of the groundwork from the technical expertise in the WAP helps to ensure that the SWS are meeting a benchmark for quality that has been vetted by field practitioners.

The SWS are intended to provide a foundation for the home energy upgrade industry that will be expanded and updated as technologies and practices change. A customizable online tool has been developed to help make the SWS easy to use by the industry. An application program interface (API), or universal translator, is available to allow organizations to fine-tune the content of the SWS to their particular needs. The SWS online tool can be used to create customized work orders, training manuals, or inspection checklists. The multifamily categories covered in the SWS include:

  • Health and Safety
  • Air Sealing
  • Insulation
  • Heating and Cooling
  • Ventilation
  • Base Load

For example, the online tool gives contractors working strictly on hydronic heating the opportunity to use content from the SWS to populate their recommended measures list. The SWS online tool has a variety of uses, from development of contract documents to measure installation, all with the ultimate objective of helping the user to install energy efficiency measures to the highest quality standard.

The SWS bring together more than 30 years of building science expertise from within the WAP and the greater home performance industry. The SWS provide a common yardstick against which consumers, financiers, and policy makers can measure the installation success of the energy efficiency measures.

Quality Assurance: Multifamily Job Task Analyses

The SWS define what a top-quality installation of an energy efficiency measure looks like. Once we know what the work is, we can figure out what the worker needs to know in order to do a job right. The Job Task Analysis (JTA) helps us to do so.

The goal of the "Guidelines for Home Energy Professionals" project is to provide an objective measure of the quality of the work and the quality of the training, and a mechanism to ensure that workers know what is expected of them to perform a high-quality job. The JTA is a formal way to analyze and document what workers need to know and to be able to perform as part of a given occupation. The JTAs being developed as part of the Guidelines project follow the DACUM (Develop a Curriculum) process—an occupational analysis method that can be applied to the development of training curricula, job descriptions, and credentialing of workers, among other things. The development of JTAs is overseen by a psychometrician, a professional who specializes in ensuring the validity of products related to testing and evaluation. The psychometrician leads a group of subject matter experts in determining what knowledge, skills, and abilities a worker needs to possess in order to do his or her job right.

At the start of the Guidelines project, it was WAP's objective to create JTAs for the four most common weatherization and home energy upgrade jobs that affect the single-family program. As the WAP's multifamily efforts have evolved, it has become apparent that there is a need to define the knowledge and skills required of the professionals engaged in this important and growing component of the program. After examining existing products, including the DOE's commercial JTAs, an NREL study determined a need to develop four separate JTAs specific to the multifamily building sector.

learn more

Download the "Technical Guidelines for Multifamily Energy Audits," which will be available in fall 2013.

Learn about the MulTEA Weatherization Assistant user interface.

See the licensing portal for the MulTEA calculation engine.

The SWS for Multifamily Energy Upgrades online tool.

Download the Four Multifamily-Specific JTAs, which will be available in November 2013.

The four Multifamily-Specific JTAs are:

  • Building Operator
  • Retrofit Project Manager
  • Energy Auditor
  • Quality Control Inspector

Multifamily buildings are often difficult to classify. They can exist in an undefined space between single-family and commercial structures. This has resulted in a long list of technical issues, ad hoc policies, and procedures for working on multifamily buildings, and has created a lot of confusion in the industry. The JTAs will help define the multifamily buildings as an independent building type, and will give structure to the expectations of the professionals who work on them.

Well-defined multifamily JTAs will help lay the foundation for the development of multifamily building standards, training programs, and the credentialing of workers. The JTAs define what a multifamily professional needs to know in order to do the work right and will ensure that multifamily energy upgrades are completed to the highest standards.

When Can I Start?

The WAP-developed multifamily resources are open source and are available to anyone wishing to perform a multifamily energy upgrade. By design, these resources are intended to help practitioners through the process, using consistent and nationally supported tools. Performing a multifamily energy upgrade is a long and complicated process, as we have seen. The WAP suite of technical resources will help streamline the multifamily energy upgrade process, from data gathering all the way through to postretrofit inspection.

Jennifer Somers is the team lead for training and technical assistance and a senior policy advisor for DOE's Weatherization Assistance Program (WAP).

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