7 reports summarized

Energy efficiency research delivers useful results

Conservation Applied Research & Development (CARD)

Studying Energy Savings


This article offers summaries of seven energy efficiency reports funded by Minnesota’s Conservation Applied Research & Development (CARD) Program that contain valuable information for commercial properties and homeowners looking to cut down on their energy expenses.

The CARD Program, administered by the Minnesota Department of Commerce, provides funding for projects that identify new technologies or strategies that have the potential to maximize energy savings for commercial, industrial, or residential buildings, improve the efficiency of existing energy conservation programs, and/or measure their success at reducing carbon dioxide emissions.


Impacts of Office Plug Load Reduction Strategies: Quantifying plug load usage, the potential for reduction, and the impact on users

The objective of this study was to identify and quantify strategies for reducing plug load in commercial buildings. The authors conducted field research in a sampling size of eight commercial buildings in Minnesota. They recorded device type and measured baseline energy usage in these buildings, and then sought to identify cost and operational issues with energy reduction strategies and attitudes of occupants towards these measures. They implemented and measured four such energy reduction strategies at workstations in all eight buildings: Advanced Power Strips (APS)/occupancy sensors, computer power management (CPM), an APS/foot pedal, and a APS/foot pedal combined with a behavior campaign.


Key Takeaways:

  • Computer power management saved the most at almost every site, with an average reduction of 29% in workstation energy. The two APS measures saved 19% and 22%, respectively. Total savings depended on the equipment used, and ranged from 5 to 28% across all 8 sites.
  • When HVAC energy is factored into the overall energy savings, those savings increase by about 3%.
  • Providing incentives and assistance can go a long way to increase the adoption of computer management practices.
  • Developing a strong relationship with company IT departments can help facilitate the successful introduction of these measures at the office level.
  • Carefully calibrate company messaging for the user to ensure maximum cooperation with the new measures.

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Field Study of Tier 2 Advanced Power Strips

If you have studied anything about energy efficiency in building management, you have probably heard about plug loads. Plug loads are the energy used by products powered by an AC plug, and they represent a significant source of potential energy savings for commercial buildings. The authors of this study selected 3 buildings for further field data collection. After gathering data on baseline energy usage, they implemented two separate varieties of Tier 2 Advanced Power Strips (T2 APS): the Embertec 8PC+ and the Tricklestar PC Advanced PowerStrip+. 


Key Takeaways:

  • Embertec 8PC+ saved an average of 28% of each workstation’s energy. Tricklestar PC Advanced Powerstrip+, by contrast, saved an average of only 8% of each workstation’s energy.
  • It would take 7.6 and 14.2 years, respectively, for the energy savings from the Embertec and Tricklestar power strips to recoup the initial investment. Focus on computer power management and identifying the specific technologies best suited to your building’s situation.
  • Providing incentives and technical support to users in order to facilitate adoption can assist in the successful integration of energy-saving measures.
  • Behavior is a critical aspect of computer power management and successful usage of Tier 2 Advanced Power Strips.

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Commercial Rooftop Units in Minnesota: Characteristics and Energy Performance

Packaged roof-top units (RTUs) are incredibly common on commercial buildings throughout the United States due to their relatively low cost, reliability, and extensive distribution network. This study was conducted in order to determine the veracity—or lack thereof—of the claim that these systems often operate inefficiently.


Key Takeaways:

  • While high-efficiency RTU units exist, none were found on the selected building sites. The authors suggested that this new and growing technology could be a target for intervention by energy-saving programs.
  • Properly insulating the RTU casing reduces heating and cooling loads to the building.
  • Adding a control panel in order to precisely orchestrate RTU operation and proactively identify potential faults in the unit is another potential way for building operators to get their money’s worth. 

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Small Embedded Data Center Program Pilot

Small embedded data centers (SEDCs) are the server closets and server rooms typically found onsite in many commercial buildings. This study was conducted to determine the state of SEDCs in Minnesota, analyze energy use at selected sites, and determine potential savings for energy conservation measures. The study’s authors received 134 responses from around the state of Minnesota from buildings with SEDCs of variable size, from less than 200 square feet to a staggering 15,000 square feet in size.


Key Takeaways:

  • IT staff are already equipped with the necessary tools to reduce SEDC energy use for the building, but often lack the necessary awareness and training. Successful messaging and education on the part of utility programs can rectify this knowledge gap and facilitate energy conservation measures. 
  • Institutional purchasing policies should incorporate a requirement to purchase ENERGY STAR-certified equipment, as these can go a long way to increasing the energy efficiency of SEDCs. 
  • Conducting services in the cloud as opposed to storing data on a desktop generally increases power utilization effectiveness; any services that can be migrated to the cloud at commercial buildings should be encouraged by management.

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Improving Installation and Maintenance Practices for Minnesota Residential Furnaces, Air Conditioners, and Heat Pumps

This study focused on the energy savings potential and successful implementation strategies associated with the installation and maintenance of residential central air conditioners, air-source heat pumps, and natural gas furnaces in Minnesota homes. The study’s authors gathered their data by conducting a telephone survey of over 700 homeowners, field tests on more than 100 residential systems, and monitoring of approximately 60 central heating and cooling systems over the course of one year.The authors’ priority was to generate actionable recommendations for the utilities involved in the installation and maintenance of these systems, but there are also a number of findings that homeowners might find useful as they make decisions about their heating and cooling systems during the hot summer days and cold winter so common in Minnesota.


Key Takeaways:

  • 9 out of 10 air conditioners and heat pumps have an installation or maintenance issue that, if addressed, would improve its overall operating efficiency.
  • 1 in 6 of these underperforming systems have a potential performance improvement of 25% or more.
  • Relatively simple routine maintenance activities like replacing filters and cleaning coils account for about 20% of potential savings.
  • Air conditioners in new homes generally run about 50% more hours and use nearly 70% more energy than air conditioners in older homes, potentially because new homes are often larger and less likely to have the benefit of large trees providing shade.
  • There is limited savings potential related to the installation and maintenance of natural gas furnaces, as most new units are high efficiency and have little for professionals to adjust.


Study Videos:


Retrofitting 80% Residential Furnaces for High Efficiency: Transport Membrane Humidifier (TMH) Technology Evaluation

This study focused on the efficiency of the Transport Membrane Humidifier (TMH), an upgrade to residential standard efficiency furnaces with a name right out of a science-fiction novel. The TMH saves energy by increasing the efficiency of induced draft furnaces from the current 76-82% to an average of 90% efficiency. The purpose of this study was to explore the potential energy savings and comfort benefits of this technology while also identifying potential risks associated both with retrofitting already-existing heating equipment and the TMH’s tendency to increase humidity levels. 


Key Takeaways:

  • Real natural gas savings vary from $46-$189 per year for heating savings and $83-$342 for heating and humidification savings across several scenarios.
  • The payback of units are in the range of $1,400 to $1,900, or approximately 60% less expensive than replacing the furnace with a high efficiency unit.
  • The study’s authors projected that the TMH would be cost effective over its lifetime, with payback periods ranging from 7-10 years in total.
  • TMH technology tends to improve furnace efficiency while also beneficially elevating indoor humidity levels during Minnesota-typical bouts of cold, dry weather.
  • Payback periods tend to vary wildly (anywhere from 2.8 to 53 years), and are generally dependent on space heating load, inclusion of humidification savings, and potential upgrade incentives.

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Energy Efficiency Opportunities for Homes with High Usage

Homes with high energy usage—either in terms of electricity or natural gas—have a greater potential to reap a financial reward from implementing energy efficiency measures than homes that consume less energy. The goal of this study was to identify the factors that contribute most to high energy use in Minnesota homes and identify conservation measures that would have the greatest savings potential for homeowners seeking to save money on their utility bills. The study’s authors selected a sampling size of 100 Minnesota homes with high energy use and conducted remote and in-person assessments of the premises.


Key Takeaways:

  • Areas of highest savings potential:
    • Wherever possible, eliminate the use of portable electric space heaters, which consume up to 2,000 kWh per year
    • Install a ductless mini-split heat pump system, which can offset the energy consumed by electric heating systems
    • Continuous furnace-fan operation can represent a significant source of energy consumption—get rid of this where possible 
    • Upgrade interior lighting to something more efficient (LEDs are ideal—and a smart investment financially) wherever applicable
    • Replace your electric water heater with a heat pump water heater
  • Common barriers to efficiency:
    • Erroneous ideas about electric space heater energy use
    • Efficiency not a priority
    • Preference for familiar appliances and systems
    • Homeowners reluctant to replace inefficient equipment that is otherwise functioning well
    • Limited household budget
    • Concern that efficiency investments might not result in energy savings

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We fund projects to identify new technologies or strategies to maximize energy savings, improve the effectiveness of energy conservation programs, or document the carbon dioxide reductions from energy conservation projects.

Mary Sue Lobenstein, CIP R&D Program Administrator, Minnesota Department of Commerce
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