Building Electrification Expansion

Moving the Residential Building Sector to Expand Electrification

Christie Amero is an Associate at Cadmus specializing in building electrification. We took a few minutes to talk to Christie about her team's current project-a one of the first of its kind to analyze the actual heating season utilization, grid impacts, and performance of cold climate air source heat pump (ccASHP) systems designed for whole-home heating in the Northeast-and what drives her to look for new insights and opportunities through that work.

Christie, why is building electrification such an interesting focus for your work right now?

Building electrification of the residential sector in particular is really critical to decarbonizing our economy and reducing our greenhouse gas emissions and there's a huge opportunity to move the majority of that sector to be fully electric. In the United States, the areas of the Northeast, Midwest, and Northwest may struggle during the coldest periods of the year to use currently available ccASHP systems to meet their full heating needs, but heat pump technology and performance is constantly improving and this study will provide valuable insights to improve understanding and increase adoption in the market.

What really drives me in this work is the prospect of shifting away from fossil fuel-based sources like gas, propane, and oil to electricity which can eventually be powered by renewable sources like wind and solar. As an engineer, I love numbers and data and this current ccASHP study we're working on is very data based. It's been great to see how these systems are performing and being utilized in the field (in a real New England winter) collecting that performance data, and then analyzing it and coming up with conclusions. We're also starting to explore other related research areas, such as the impact of high global warming potential refrigerants that are used in many of the ccASHP systems and potential alternatives.

How do you respond to skepticism about residential building electrification and a major market transformation?

Yes, there is a lot of skepticism and for good reason. While there is a lot of opportunity for building electrification in the residential sector, two key challenges to widespread market adoption continue to be education around selecting the right type of heat pump system for a home and improving the cost-effectiveness of replacing existing natural gas boilers or furnaces.

There are many different heat pump system types available and a lot more work needs to be done to train contractors and customers to better understand how the systems are intended to work, what systems are best suited to particular homes, and how the customer actually plans to use the system. In some cases for this current study, we were under the impression from the contractor's information that these systems were designed to be the primary source of heating for the home. But when we spoke to the customers, they only planned to use their ccASHP system when it was above 20°F and then switch over to their traditional heating system. In that situation, the ccASHP system can end up being oversized for the customer's load and they likely won't get optimal performance.

Regarding the cost-effectiveness, until we put a carbon tax on natural gas systems it's going to be really difficult to ask homeowners with gas heat to switch to heat pumps without any sort of incentive from a local utility. Another challenge is that a lot of homes, especially in the Northeast, are more than 100 years old and while they may have had upgrades over the years, heat pump systems really work best in homes that are well insulated. So, when we're thinking about home building electrification, we need to consider programs that couple a heat pump installation or retrofit with energy efficiency upgrades such as weatherization and improved insulation.

Will the current policy environment facilitate more opportunities to overcome those challenges?

Recently the Biden Administration increased funding for the Department of Energy to do more R&D on ccASHPs, so we're expecting to see more utilities offering programs focused on heating electrification using heat pumps. However, there is still a lot of concern over customers not using the systems as intended. In our research, we've received some anecdotal feedback from utilities that have tried to offer these programs, but then have found the systems are only used for cooling, which is still pretty common especially in the Northeast.

We also heard from some customers that the contractor had told them that they should switch from the ccASHP to their backup heating system at a certain temperature. So even the contractor had doubts about its performance at low temperatures. The increased attention and funding from the current Administration is great, but if utilities are going to pursue more whole-home electrification programs, we really need a combination of contractor and customer education about the different types of systems and how to use them.

Can you tell us more about your current project and how you are drawing insights from the data you've collected?

Our team did a very intensive whole-home ccASHP metering study of 43 homes across MA and NY over the past heating season. One of the challenges to analyzing the performance of heat pump systems has been the lack of really detailed data on how different systems have performed under a variety of real-world conditions. To address this, we worked with Cadmus' Data Analytics team to design a flexible data framework that we could use to aggregate the different data sources needed to do an effective analysis. Although this is a small sample size, we can apply calculations across sites and system types to pull out more high-level conclusions and trends that can be applicable to future efforts.

What's really unique about this study is that we looked at more than just ccASHP system power and were able to calculate the heating load and performance on a granular level. Because we collected metered data for an entire heating season, and not just a couple of weeks like a typical evaluation study, we could see actual utilization for multiple system types. We also compared the measured heating loads to expected loads to better understand whether heat pump systems are being properly sized for various home types.

Another interesting element of the study is that a lot of people who participated had onsite solar. For homes that receive the vast majority of their electricity from onsite solar, they are barely paying anything for heating in a New England winter, which is pretty amazing. If we're able to start coupling ccASHP installations with sites that have onsite solar or incentivizing them in conjunction that can dramatically improve cost effectiveness of the installations.

Where do you go from here? Is there an opportunity to broaden the dataset? 

Yes, going forward there seem to be numerous opportunities to expand our data set and understanding of heat pump performance. We are looking to include data from other existing studies that may have been done in the Midwest or Northwest and use additional primary data collection to fill in some of the gaps for the rest of the country. Right now, we're focused on residential homes in the northern section of the country. We already know heat pumps perform well at 30°F or 40°F for the southern portion of the country, but we need more insight into these extreme cold periods, especially the -10°F and -20°F temperatures they get in the Midwest. Taken together, all these insights will help drive utilization of ccASHP technology in the marketplace and greatly improve our understanding of how to accelerate market adoption of this exciting technology.

Christie, can you tell us a little about yourself and what brought you to Cadmus?

I studied mechanical engineering at Northeastern and was able to work at a couple of different companies through their co-op program. One of my rotations was a gasification company where they were designing a system that would take waste materials and use them in a combined heat and power plant to generate energy. That's when things really clicked for me and I realized that I wanted to use my degree to do good things in the world. I was really interested in thinking about how we could reduce our impact on the planet. I worked in the Boston area in energy efficiency for several years before moving out to Boulder, CO, and starting my career at Cadmus. I have a strong connection to nature and I love being able to say that my career is having a positive impact on the planet and the places that I enjoy every day.

Is the Northeast Ready for Residential Electrification?

Winter is coming...

Christie Amero, a senior associate on the Cadmus' DER team, presented at the 2022 ACEEE Summer Study on residential electrification in the northeast.

Achieving decarbonization goals requires significant reduction or elimination of fossil fuel heating systems in buildings, and strategic heating electrification has been identified as a primary pathway for decarbonizing residential buildings. To date, most market development programs have focused on installations of supplemental cold climate air source heat pumps (ccASHP), which typically serve less than 70% of a home's total heating load. However, achieving decarbonization targets in the Northeast will require widespread deployment of wholehome or primary with backup ccASHPs; that is, systems that serve 70% or more of the load. To design successful residential electrification programs, policymakers need to assess ccASHP customer satisfaction, technical performance, and electric grid impacts to ensure that customer experience and in-field performance achieve expected performance standards and determine the scale of necessary grid infrastructure upgrades.

In collaboration with E4TheFuture, Massachusetts Clean Energy Center (MassCEC), New York State Energy Research & Development (NYSERDA), and U.S. Department of Energy, the Cadmus team conducted the Residential ccASHP Building Electrification Study. Key research included assessing customer satisfaction and collecting and analyzing detailed heating and cooling season metered data to compare utilization, delivered heating capacity, performance, and grid impacts of ccASHP systems. The team metered outdoor, supply, and return air temperatures and total system, supply fan, and backup electric resistance power for 73 ccASHP systems in 43 homes, calculating an average overall heating season performance of 2.34 sCOP.

This paper explains the data collection and analysis methodology, describes study findings on five key objectives, and presents conclusions and program recommendations to address winter peak demand impacts and encourage greater adoption of whole-home ccASHPs

Click here to read the paper.

Authors: Christie Amero, Conner Geery, Nathan Hinkle, and Neil Veilleux

Applying Advanced Data Analytics to Assess Building Electrification Deployment

Understanding in-field performance is the key to spurring market transformation in home electrification.

Space and water heating account for about 30% of the total emissions in the Northeast. Achieving energy and climate priorities in the Northeast-and across the U.S.- requires utilities and energy agencies to transform the way the built environment is heated and cooled, transitioning buildings away from fossil fuel combustion and to renewably powered heat pumps. To facilitate this transition, policymakers require detailed datasets assessing whole home heat pump performance, that is heat pumps serving 90% or more of home heating load, to inform program design-an analysis that is especially important as states deploy the billions of dollars in IRA funding to spur market transformation in home electrification.

Today, most building thermal loads are served by fossil fuels, including oil, gas, or propane. While the use of cold climate electric heat pumps for both space and water heating has increased over the last decade, the technology has primarily been used for supplemental heating loads (e.g., serving 60% or less of the heating load). Decarbonization of the buildings will require massive deployment of whole home heat pumps, defined as heat pump systems that serve 90% or more of the heating load; however, policymakers have lacked robust datasets on actual, in-field performance and customer satisfaction of whole home heat pumps, resulting in uncertainty about technology performance.

To address these concerns-and drive forward action on building decarbonization-Christie Amero and her team took a deep dive into the performance of whole home heat pump systems, assessing customer satisfaction, utilization, and metered, in-field performance during a typical Northeast winter.

Amero selected over 40 homes across Massachusetts and New York that use their heat pump systems as the primary heating source for in-field metered data collection. In contrast to typical evaluation studies, she focused not only on energy consumption and peak demand, but also assessed what the actual average heating performance was for these systems during a typical heating season and if any backup heating systems were used at these homes. To measure delivered heating load and estimate performance, Amero and her team installed interior supply and return temperature sensors and recorded the indoor heat pump fan power. Then, in combination with the total system demand that was measured at the outdoor unit, she was able to estimate the actual heating performance of the system.

Amero recorded data for each of these points at two-minute intervals for three to seven months, depending on the site. This resulted in millions of data points that her team analyzed in Cadmus' SQL- based data warehouse. Here she used the data warehouse to stores and analyzes the data, all in one place. She was then able to create an interactive dashboard using Power BI (Business Intelligence) to visualize the results and summarize key objectives (see Figures X and Y). The dashboard gives project stakeholders the opportunity to interact directly with the data. Christie explained her excitement for the Power BI dashboard, "Being able to visualize huge amounts of data in Power BI is exciting and brings out my inner nerd because I love being able to manipulate and work with the data to pull out trends. Our clients loved the accessibility and ease of data visualization." Working with a compiled dataset for multiple homes and systems allowed our team to extract heating and cooling load, performance, and electric demand impact conclusions over a range of parameters, including outdoor air temperature, home weatherization level, system type, and capacity.

When asked about what is next for heat pump data collection, Christie responded, "I would like to expand this project across the Northeast and the country to collect broader datasets in multiple climate zones and be able to provide statistically significant results. This data will be critical to inform next generation policy and program design, especially as states and the federal government invest billions of dollars in home electrification."

Click here to read the paper.

Sonoma Clean Power Identifies a Path to Electrification for Two School Bus Operators in California

Tangible Paths for Implementing an All-Electric School Bus Deployment

In 2020, Sonoma Clean Power (SCP) selected the Cadmus Group to conduct its school bus electrification study for the Mendocino Unified School District (MUSD) and the West County Transportation Agency (WCTA).

Challenge

SCP recognized that the switch to all-electric buses for MUSD and WCTA's school bus fleets was a daunting task without the guidance and support of a roadmap. Cadmus was asked to develop short- and long-term recommendations for achieving fleet electrification.

Solution

Cadmus met with the two school bus agencies to assess their existing fleets, discuss route operation requirements, and to identify their current electrical infrastructure capacity and potential upgrades. By identifying the best routes to deploy electric school buses, Cadmus was able to recommend specific bus makes and models, charging equipment, and charging protocols to maximize utilization and minimize costs. The study also included a solar potential analysis and provided guidance on available funding and financing programs.

Cadmus modeled bus and route suitability using an Excel-based, 24-hour model with 15-minute increments with weather data for the coldest winter and warmest summer days using actual 2019 meteorological weather data. We incorporated bus model and charger parameters-including bus weight, battery capacity, maximum charger power rating, HVAC system ratings, and bus performance (in electric energy consumption per mile)-collected from original equipment manufacturers and published specification sheets. For each bus and route combination, we modeled the battery state of charge for each hour of the day and an energy breakdown of each subsystem, as illustrated in the figures below.

In addition to our fleet modeling services, we provided guidance on integrating onsite solar energy systems to offset the added electric cost of electric bus charging and recommended applying for various statewide and national grants.

Results

The Cadmus team developed tangible paths to implement an all-electric school bus deployment for the two fleet operators: West County Transportation Agency and Mendocino Unified School District. Each agency was given a report by Cadmus outlining short- and long-term recommendations for achieving fleet electrification. SCP has shared some of the findings of this report as described below.

For the West County Transportation Agency:

• The existing electric grid infrastructure for WCTA's main bus yard may already be capable of supporting over 80 battery electric bus (BEB) EB chargers; WCTA's new parking area appears to have the capacity for at least five BEB chargers.
• There is at least one commercially available Type A BEB model currently on the market that can meet WCTA's energy needs for four out of the six bus routes selected for analysis.
• The two WCTA bus routes that cannot be served by Type A BEBs currently on the market operate over 140 miles per day. However, the BEB market is constantly evolving and WCTA can and should discuss their route requirements and interest in higher range with manufacturers.
• WCTA's main bus yard and new parking area have sufficient room for a total solar photovoltaic (PV) capacity that could offset the annual energy consumption of nine BEBs.

For the Mendocino Unified School District:

• There are commercially available high-range BEB models on the market today that can meet MUSD's energy needs for all five routes.
• While adding a BEB to MUSD's fleet would increase the average monthly electricity bill by approximately $480 per vehicle, MUSD could save approximately $270 per route per month in net fuel costs.
• MUSD could install up to 65 kW-DC of solar photovoltaic energy at their bus barn, which could offset the annual energy consumption of at least two (2) BEBs.

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