Metrics for Energy Efficient Buildings: How Do We Measure Efficiency?

September 27th, 2016
efficiency level conceptual meter indicates 100 percent, isolated on white background

When it comes to an entire house or building, or comparing homes or buildings, what should the measurement be?

Some measurements are very direct like the height cleared by the Olympic high jumping gold medalist this summer. Efficiency has a number of nuances, though, that make measuring it difficult in terms that allow consumers to make informed decisions. When it comes to an entire house or building, or comparing homes or buildings, what should the measurement be? And how should you compare energy use on-site versus off-site? How do you determine what is efficient about the building versus the operations of the building? And how should renewable energy use or the time of energy use, and time-dependent cost of energy use factor in? Should the emissions of the source of the energy used be factored? To learn more, read the paper written by FSEC’s Deputy Director Philip Fairey and Natural Resources Defense Council’s David Goldstein.

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Metrics for Energy Efficient Buildings: How Do We Measure Efficiency?*


*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA in August  2016.

Can a Water Heater Help Cool Your House?

September 27th, 2016
Heat pump water heater inside laundry room of house, photo.

Heat pump water heaters were tested in the lab and in the field.

Most electric water heaters use an electric resistant rod in the tank. But there is another option for electric water heaters – one that is familiar to most Floridians, and that is a dedicated heat pump for heating hot water. Just like a regular heat pump for heating the air in your house, the heat pump water heater has a small compressor unit on top that uses vapor compression to heat the water. Prior FSEC research on heat pump water heaters (HPWH) in Florida showed that they saved approximately 66% of the energy needed to heat water with an electric resistance system. HPWHs also create a quantity of cooled, dehumidified air from the compressor section of the unit as a by-product of their operation. FSEC researchers found out that a HPWH coupled to the conditioned living space can reduce space-conditioning energy in a cooling-dominated climate, but with qualifications a lab test was undertaken to investigate the effect of coupling a garage located HPWH to the conditioned space with ductwork. With the HPWH ducted to and from the interior, cooling energy dropped by 4% or 0.8 kWh/day. Effect on space heating energy for this configuration could not be determined. Experiments also investigated using an outdoor air source for the HPWH, to supplement ventilation. During the cooling season, the HPWH tempered the outdoor air with only a minimal impact on cooling energy. Space heating energy increased by 18% or 1.4 kWh/d. The space coupling of the HPWH had a minimal impact on water heating efficiency.

In later field evaluation, eight occupied homes were retrofitted with a HPWH coupled to the conditioned space. Results were more pronounced than the lab evaluation: cooling energy savings averaged 8% (1.1 kWh/day). Space heating energy use increased by 24%, although with considerable variation and little application in Florida’s mild climate. The evaluation suggested the coupling eroded some of the HPWH water heating energy use savings, reducing it by 0.4 kWh/day or 11%. If not located in the house, you often end up with a slightly cooler garage.

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Measured Performance of Ducted and Space-Coupled Heat Pump Water Heaters in a Cooling Dominated Climate*


*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.

Getting to a Near-Zero Energy Existing Home

September 27th, 2016
Rear view of house with screened in back porch and solar electric array with 36 panels on roof

Near-zero energy use home after deep energy retrofits.

Monitoring results over a four-year period document a phased retrofit applied to a central Florida home with very high electricity consumption, eventually ending in a home with near-zero energy use. The retrofit included simple pass-through measures, such as the installation of efficient lighting and low-flow shower heads, as well as deeper measures which included a high-efficiency space heating and space cooling controlled by a smart thermostat, a heat pump water heater, and ENERGY STAR® appliances. The average household electricity use was reduced through a combination of these efficiency measures and photovoltaic power generation by 82%. Results from the case study, and nine other deep retrofits suggest how an effective zero-energy home (ZEH) program can be implemented in otherwise poorly performing existing homes.

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From Energy Guzzler to Near-Zero Energy Home: Lessons from the Phased Deep Retrofit Project

*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.

A More Efficient Way to Dry Clothes?

September 27th, 2016
Clothes and towels inside the dryer, photo.

Clothes dryers with heat pump technology were installed in eight project field homes.

Electric clothes dryers represent 5% (790 kWh) of annual energy use in Florida homes. Clothes dryers with heat pump (HPCD) technology, which use substantially less energy than standard resistance dryers, are relatively new to the domestic market. In eight FSEC project field homes, electric resistance clothes dryers were replaced with a new unvented HPCD. The estimated median energy savings are 34% (264 kWh/year or 0.72 kWh/day), and average annual savings are 36% (308 kWh/year or 0.9 kWh/day).

Dryer energy use graph, site 25, January 2014 to December 2015

Energy use showed saving more than 30 percent.

Although HPCDs use less electricity than standard resistance dryers, they still release a significant amount of heat from their operation. The unvented units that were located inside the home led to very high utility room temperatures and increases in space-cooling energy that may compromise identified savings; this is an issue the manufacturer is addressing. Given the heat issues, these unvented appliances are appropriate in Florida only if they will be installed outside of the conditioned space—typically in the garage. We further speculate, based on observed findings, that another technology—vented heat pump clothes dryer—may be the most appropriate dryer system type for Florida conditions.

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Measured Performance of Heat Pump Clothes Dryers*


*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.

Does Purchasing a Supplemental High-Efficiency Mini-Split Heat Pump Make Sense?

September 27th, 2016
Mini split air conditioning fan above interior house door near stairway, photo.

Ductless mini-split heat pumps were installed in the main living area of 10 Central Florida homes.

In Florida, space heating and space cooling is customarily accomplished by central systems with unavoidable air distribution losses as ducts – often leaky – pass through unconditioned space. High-efficiency 1-ton, supplemental, inverter-driven ductless mini-split heat pumps with a 25.5 seasonal energy efficiency ratio (SEER), and 12 heating seasonal performance factor (HSPF), were installed in the main living area of 10 central Florida homes with the goal of reducing space heating and cooling energy by decreasing runtime of these less efficient systems. The SEER rating is 1.8 times as efficient as the new federal minimum level for conventional central systems and even more efficient than the older systems in these homes

Installed as a supplement, the mini-split installations showed median energy savings of 33% (6.7 kWh/day) for space cooling and 59% (6.5 kWh/day) for heating in the existing homes where they were added. An added consumer benefit is a redundant heating and cooling system, creating tolerable interior conditions during main system failures.

Two additional homes received high-efficiency, ductless heat pumps as complete central system replacements – a single ducted unit and a multi-split design. These homes exhibited cooling energy use savings of 37% (7.8 kWh/day) and 29% (3.5 kWh/day), respectively. While significant cooling savings were measured, the multi-split installation suffered comfort issues. The mini-split replacement, however, showed superior interior moisture control and maintained the space 1oF lower on average.

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Evaluation of Mini-Split Heat Pumps as Supplemental and Full System Retrofits in a Hot Humid Climate*


*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.

Can Smart Thermostats Save Energy?

September 27th, 2016
NEST thermostat reading 76 degrees installed on wall

“Smart” thermostats were installed in over 30 research homes.

Thermostats are the central switch that controls operation of heating and cooling systems—commonly the largest energy end use in homes. That energy setup/setback has potential for energy savings has been demonstrated repeatedly in well-controlled evaluations. Thus understanding how the occupants and thermostat interact is key to controlling energy use. Programmable thermostats have often been bypassed by occupants. Newer “smart” thermostats get around these problems by self-programming depending on heuristic or machine learning evaluation of user control habits as well as sensed occupancy. These modern devices use a combination of data on occupancy, weather, and thermostat-setting preference to help consumers with automated setback/setup schedules.

Researchers at FSEC installed smart thermostats, primarily the Nest Learning Thermostat, in more than 30 research homes. A full year of sub-metered hourly temperature and heating and cooling system operation data were available prior to the installation of the smart thermostat allowing detailed evaluation of temperature-related changes. Overall measured heating and cooling energy savings averaged 9.5% with some significant variation among homeowners.

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Evaluation of the Space Heating and Cooling Energy Savings of Smart Thermostats in a Hot-Humid Climate using Long-term Data*


*This paper was presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings in Pacific Grove, CA on August 22 -26, 2016.

EV Transportation and Technology Summit 2016

September 22nd, 2016

What are the latest developments in electric vehicle technology, policy and planning? Find out at the EV Transportation and Technology Summit on October 17-20, 2016.

EV Summit 2016 logo

The EV Transportation & Technology Summit 2016 will focus on transportation planning and infrastructure.

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USDA Subsidized Energy Audits for Florida Ag Producers and Rural Small Businesses

September 22nd, 2016

By Janet McIlvaine

The University of Central Florida’s FSEC conducts energy audits, renewable energy assessments, and technical assistance for the USDA Rural Energy for America Program (REAP) grant and loan program which is specifically for renewable energy systems and energy efficiency improvements. Any Florida agriculture operation or rural small business is eligible for FSEC support. The USDA subsidizes 75% of FSEC’s audit cost.

Two FSEC employees review solar access maps with business owner.

Solar access maps are produced and reviewed with business owners as part of FSEC’s technical assistance.

The audit includes an on-site visit to inventory energy use, utility bill analysis, evaluation of efficiency improvement options, projected annual energy savings, all summarized in a REAP-required Technical Report, and assistance with completing the technical portions of the application. Grants are eligible for up to 25% of eligible project costs and range from $2,500-$500,000 for renewable energy systems and $1,500-$250,000 for energy efficiency improvements.

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Join Us Online! Electric Vehicles: At the Intersection of Transportation and Energy

September 20th, 2016

This month’s UCF Energy Connections Seminar, “Electric Vehicles: At the Intersection of Transportation and Energy,” is now being offered online.

On Wednesday, Sept. 20, 2016 at 11 a.m., please join the seminar from your computer, tablet or smartphone.

You can also dial in using your phone. United States +1 (646) 749-3131
Access Code: 570-064-253

First GoToMeeting? Try a test session:

UCF Energy Connections Seminar Series

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UCF Energy Connections Seminar Series – September 2016

September 19th, 2016

Electric Vehicles: At the Intersection of Transportation and Energy

Presented by: Dr. Paul Brooker

When: September 21, 2016 @ 11 a.m.
Location: FSEC, 1679 Clearlake Rd., Cocoa, FL 32922. Auditorium

Since the introduction of the automobile in the early 1900’s, there has traditionally been a separation between transportation energy and residential/commercial/industrial energy. With electric vehicles on the rise, however, energy will need to flow freely between vehicles and the grid.

UCF Energy Connections Seminar Series

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As we move towards this intersection, we will begin to encounter conflicts between the needs of the vehicle owner and the desires of the grid/building energy operator. For example, the electric vehicle owner is concerned about getting home every day, and ensuring that the battery’s lifetime is not adversely impacted. The grid operator is concerned with maintaining high power quality and reducing the risk of outages as renewable energy sources are increasingly added to the mix. Understanding distinctive needs of each user will lead to better management of energy flows that can benefit transportation, the grid, and society as a whole. This presentation will explore how the needs of the vehicle may be met, while also providing added value to the grid.

Dr. Paul Brooker Biographical Sketch

Dr. Brooker received his B.S. in Chemical Engineering from Brigham Young University in 2004 and his Ph.D. from the University of Connecticut in 2009. After graduating, Dr. Brooker came to UCF’s FSEC, where he has participated in research ranging from fuel cells to electric vehicles to solar photovoltaics.

Within the DOE-sponsored Fuel Cell High Temperature Membrane Working Group at FSEC, Dr. Brooker’s role was to apply electrodes onto novel membranes, and to investigate the performance in an operating fuel cell environment. In addition, Dr. Brooker investigated the use of heteropolyacids (HPAs) for reducing membrane degradation during accelerated stress testing. As part of the Electric Vehicle Transportation Center (EVTC), Dr. Brooker has modeled the use of fuel cells in electric vehicles, as well as electric vehicle infrastructure needs. His research is investigating the potential for fuel cell vehicles to contribute to energy needs beyond transportation, such as grid ancillary services, back-up power, and distributed energy resource management. Dr. Brooker is a project leader within the Photovoltaic Manufacturing Consortium, where he is directing research on diamond wire slicing of silicon ingots. This research is investigating methods to understand diamond wire wear and its effect on the surface of the cut wafer. This understanding could lead to improved control of wafer surfaces, reduced consumption of diamond wire, and increased wafer throughput, all by optimizing the slicing parameters.