Field Notes Research Update — November 2015
Center for Energy and Environment conducts technology and market assessments to identify tomorrow’s best clean energy strategies. Our research staff produces studies on building science, mechanical system performance, and program and policy design.
This blog post is taken from our Field Notes newsletter which features updates on CEE's research projects. Sign up for Field Notes to get this information in your inbox!
Fall 2015 Research Updates:
Enhancing commercial energy code compliance
Commercial energy codes specify design requirements that achieve a minimum level of energy efficiency in new buildings, additions, and renovations. This project provides tools and technical assistance to design, development, and code enforcement professionals to help improve compliance with the most commonly neglected and highest-impact energy code requirements. The first steps for this research were to determine the types of buildings and code line items that would have the biggest impact on energy savings by answering the question, “What are the most cost-effective, impactful energy savings items that are being missed with current code compliance?”
The team started by completing a detailed review of Minnesota commercial energy code changes and looking at information on past code compliance. To gain a better sense of the compliance challenges, staff then conducted interviews with 13 Minnesota professionals and 16 officials from states already using the code now required in Minnesota. Based on the information gathered, the project team developed a list of key energy code items to be included in a small buildings pilot program and compiled a quick reference guide summarizing the items. Project staff are now recruiting buildings to participate in the pilot program. Participating buildings will receive the energy code reference sheet, as well as preliminary plan review services to support design teams in meeting energy codes and to help industry professionals achieve higher savings through better energy code compliance. At least 30 projects will receive these support services over the next two years.
Cold climate air source heat pump field assessment
Air source heat pumps (ASHPs) have the potential to improve space heating efficiency and reduce energy costs for houses in cold climates where natural gas is unavailable. This study assesses the efficiency and reliability of new generation ASHPs in Minnesota’s cold climate homes to determine how to best integrate this technology into utility efficiency programs. The project team has completed the assessment phase, which included identifying the equipment presently available and determining how ASHPs currently are included in utility rebate programs. The process also revealed issues with contractors’ lack of familiarity with newer cold-climate ASHPs, specifically around integration with existing systems and adjusting control settings so that ASHPs continue to operate at the colder temperatures specified by manufacturers.
The project team selected five houses that cover a range of installers, locations, and equipment. All installations should be completed by early December, with performance monitoring lasting 10 to 12 months. While the goal is to integrate the ASHPs with existing equipment, many sites have required an update to new equipment. In these instances, field staff will use modeling to show how the ASHPs would have performed with the existing systems. Staff will use information and data gathered during the assessment and field monitoring to determine the types of houses that would most benefit from ASHPs and where targeted incentive programs would be most effective.
Using an aerosol sealant to reduce multi-unit dwelling envelope air leakage
While tight exterior envelopes have become standard for single-family homes, these construction practices are just starting to be applied to the multifamily sector. This research is designed to determine whether the aerosol sealant method developed by project partner UC Davis Western Cooling Efficiency Center (WCEC) is a cost-effective way to reduce envelope air leakage in Minnesota multifamily buildings. The project team has completed air sealing work on 18 units in three new construction buildings. Results show that the sealing process typically required 60 to 90 minutes of injection and resulted in envelope leakage reductions of 70% to 95%. The envelope leakage ranged from 0.2 to 1.4 ACH50 with more than half of the units achieving a leakage more than 80% below the code requirement of 3.0 ACH50. EnergyPlus models for three different ventilation strategies in new and existing buildings showed HVAC energy savings of 6% to 26%.
Existing buildings have presented additional challenges to the sealing process, as they have been two to five times leakier than new construction. This can cause problems with fan capacity and lead to an increase in sealing times, which in turn impacts how sealant settles on horizontal surfaces. In addition, researchers found airflow in older buildings (with enclosed floor plans) to be very different than in newly constructed buildings (with open floor plans), requiring staff to adjust their sealing strategies in the field. However, the air sealing achieved relative leakage reductions of 45% to 80% and greater reductions in absolute leakage and energy use.
Given the successful sealing results, WCEC is working with the company Aeroseal to develop equipment that is commercially available to contractors. Research principals from Aeroseal will travel to Minnesota later this month to observe the sealing processes in the final buildings and familiarize with the technology.
Field study of a moisture and heat transfer furnace retrofit device
Single-family space heating is among the largest end uses of energy in Minnesota and, as few furnaces are rarely replaced before failure, there is immense potential for savings through furnace retrofits. New transport membrane humidifier (TMH) technology can retrofit older, mid-efficiency furnaces to significantly increase their energy efficiency. TMH technology is not yet available commercially, so researchers needed to complete some additional background research and pursue additional considerations before moving forward. Most of the challenge revolves around how the TMH technology impacts indoor air quality in a variety of single-family environments. One key detail of the project is to understand how the increased furnace efficiency is distributed between the increased thermal efficiency and the humidification benefit.
The next step is to install and monitor TMH technology at five houses that were selected to represent the range of moisture generation and air infiltration conditions in Minnesota homes. The project team has installed the technology at the first house and alternating mode tests have begun. The team is working on installs for the remaining sites. As TMH is new technology and in-house moisture is a complicated issue, the data collected in this project will be extremely helpful in fully understanding the impact of the technology, in terms of both energy savings and humidification.
Quality installation and retrocommissioning of condensing boilers *
While high-efficiency condensing boilers have been available in the residential market for many years, consumer acceptance and market penetration is low. One contributing factor is the concern that many installed boilers are not achieving their listed efficiency. As a result, some utilities have eliminated rebates and most HVAC contractors are not recommending condensing boilers to their customers. This project is developing new approaches to increase the efficiency of condensing residential boilers through both retrocommissioning and improved installation methods. CEE is handling the field work for this study, while project lead the Neighborhood Energy Connection completes interviews with contractors, homeowners, and utility staff to get a better sense of the issues and perceptions around condensing boilers.
The first phase of the field work is already under way — the project team has installed monitoring equipment at seven sites to characterize existing boilers, and then determine practical and cost-effective steps to improve performance. Next year, the second phase will include installing and characterizing new boilers, as well as fixing existing boilers to improve their efficiency.
Commercial building plug load energy reduction strategies *
Plug load energy use in commercial buildings is the fastest growing end use in U.S. commercial buildings, in stark contrast to decreases in other end uses such as cooling and lighting. This project characterizes commercial building plug load and evaluates various reduction strategies. In partnership with project lead Seventhwave, CEE is primarily responsible for measurement and verification. Architecture firm LHB is also a partner. The first step for CEE’s project team was to select and fully understand the monitoring equipment that would be used, ensuring that it would serve the project’s purpose and collect the appropriate data. Monitoring has been completed at two sites, and is currently ongoing at an additional two sites with two more sites confirmed. At each site, the project team installs monitoring equipment and completes an inventory of the office. Initial monitoring lasts one month, after which the project team returns to install new treatments aimed at reducing plug load, such as occupancy sensors and foot pedals to easily turn off power strips. The project is also looking at other strategies like computer power management and behavior management strategies.
A research program of the U.S. Department of Energy, Building America is designed to promote the development of innovative, cost-effective solutions to reduce energy use in buildings. CEE recently completed three projects for Building America. The final report for the combustion safety project is now available and the reports for the other two projects will be published in the next few months:
Simple retrofit high-efficiency natural gas water heater field test
Most condensing high-efficiency gas water heaters are not cost effective to install, and tankless water heaters can cause problems with performance and temperature. This project assessed the performance of hybrid water heaters to determine whether they are a good alternative to other high-efficiency models. Monitoring completed at four houses found they eliminated almost all performance concerns and greatly reduced installation cost. Although overall paybacks are longer than 10 years, hybrid water heaters do provide a more cost-effective solution over other high-efficiency water heaters.
Combined space and water heating: Measure guidelines, installation and optimization
This measure guideline offers a practical guide to navigate the complexities of combined space and water heaters. The guideline includes information on contractor training and an overview of the savings potential, as well as instructions on how to get existing equipment to work properly and verify that system changes are completed correctly.
Combustion safety simplified test protocol field study **
This project developed and evaluated a simplified combustion safety test procedure that could quickly identify the potential for water heaters, furnaces, and boilers to have significant spillage issues during normal operation. Project staff selected and monitored houses (10 in Minnesota and 1 in Wisconsin) to identify how often and under what conditions combustion spillage occurred, and to verify whether the simplified protocol properly identified water heaters with significant spillage issues.
These projects are supported in part by a grant from the Minnesota Department of Commerce, Division of Energy Resources through the Conservation Applied Research and Development (CARD) program. And with co-funding by CEE in support of its nonprofit mission to advance research, knowledge dissemination, and program design in the field of energy efficiency.
* CEE is subcontractor on these projects.
** This project was conducted in partnership with the University of Minnesota, University of Illinois, Gas Technology Institute, and Seventhwave.