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At least 91 records · Page 5

Building America Case Study: Performance of a Hot-Dry Climate Whole House Retrofit, Stockton, California (Fact Sheet)

The Stockton house retrofit is a two-story tudor style single family deep retrofit in the hot-dry climate of Stockton, CA. The home is representative of a deep retrofit option of the scaled home energy upgrade packages offered to targeted neighborhoods under the pilot Large-Scale Retrofit Program (LSRP) administered by the Alliance for Residential Building Innovation (ARBI). Deep retrofit packages expand on the standard package by adding HVAC, water heater and window upgrades to the ducting, attic and floor insulation, domestic hot water insulation, envelope sealing, lighting and ventilation upgrades. Site energy savings with the deep retrofit were 23% compared to the pre-retrofit case, and 15% higher than the savings estimated for the standard retrofit package. Energy savings were largely a result of the water heater upgrade, and a combination of the envelope sealing, insulation and HVAC upgrade. The HVAC system was of higher efficiency than the building code standard. Overall the financed retrofit would have been more cost effective had a less expensive HVAC system been selected and barriers to wall insulation remedied. The homeowner experienced improved comfort throughout the monitored period and was satisfied with the resulting utility bill savings.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Performance and Costs of Ductless Heat Pumps in Marine Climate High-Performance Homes: Habitat for Humanity -- The Woods, Tacoma, Washington

The Woods is a Habitat for Humanity (HFH) community of ENERGY STAR Homes (c) Northwest (ESHNW)-certified homes located in the marine climate of Tacoma/Pierce County, Washington. This research report builds on an earlier preliminary draft 2014 BA report, and includes significant billing analysis and cost effectiveness research from a collaborative, ongoing Ductless Heat Pump (DHP) research effort for Tacoma Public Utilities (TPU) and Bonneville Power Administration (BPA). This report focuses on the results of field testing, modeling, and monitoring of ductless mini-split heat pump hybrid heating systems in seven homes built and first occupied at various times between September 2013 and October 2014. The report also provides WSU documentation of high-performance home observations, lessons learned, and stakeholder recommendations for builders of affordable high-performance housing such as HFH.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Northwest Energy Efficient Manufactured Housing Program High-Performance Test Homes; Whole-House Solutions for New Homes, Energy Efficiency & Renewable Energy (EERE)

?This project represents the third phase of a multi-year effort to develop and bring to market a High Performance Manufactured Home (HPMH). The scope of this project involved building four HPMH prototypes, resulting in what is expected to be a 30% savings relative to the Building America Benchmark. (The actual % savings varies depending on choice of heating equipment and climate zone). The HPMH home is intended to make significant progress toward performing as zero-net-energy ready. Previous phases of this project created a HPMH specification and prototyped individual measures from the package to obtain engineering approvals and develop preliminary factory construction processes. This report describes the project team's work during 2014 to build prototype homes to the HPMH specifications and to monitor the homes for energy performance and durability during 2014. Monitoring is expected to continue into 2016. home is intended to make significant progress toward performing as zero-net-energy ready. Previous phases of this project created a HPMH specification and prototyped individual measures from the package to obtain engineering approvals and develop preliminary factory construction processes. This report describes the project team's work during 2014 to build prototype homes to the HPMH specifications and to monitor the homes for energy performance and durability during 2014. Monitoring is expected to continue into 2016.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Predicting Envelope Leakage in Attached Dwellings (Fact Sheet)

'The cost for blower testing is high, because it is labor intensive, and it may disrupt occupants in multiple units. This high cost and disruption deters program participants, and dissuades them from pursuing energy improvements that would trigger air leakage testing, such as improvements to the building envelope.' This statement found in a 2012 report by Heschong Mahone Group emphasizes the importance of reducing the cost and complexity of blower testing in multifamily buildings. Energy efficiency opportunities are being bypassed. The cost of single blower testing is on the order of $300. The cost for guarded blower door testing, the more appropriate test for assessing energy savings opportunities, could easily be six times that and that's only if you have the equipment and simultaneous access to multiple apartments. Thus, the proper test is simply not performed. The objective of the 2013 research project was to develop the model for predicting fully guarded test results (FGT), using unguarded test data and specific building features of apartment units. The model developed has a coefficient of determination R2 value of 0.53 with a root mean square error (RMSE) of 0.13. Both statistical metrics indicate that the model is relatively strong. When tested against data that was not included in the development of the model, prediction accuracy was within 19%, which is reasonable given that seasonal differences in blower door measurements can vary by as much as 25%.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Evaluation of the Performance of Houses With and Without Supplemental Dehumidification in a Hot-Humid Climate, New Orleans, Louisiana (Fact Sheet)

This report, Evaluation of the Performance of Houses with and without Supplemental Dehumidification in a Hot-Humid Climate, describes a research study that that was conducted by the Building Science Corporation (BSC) Building America Research Team. BSC seeks to research and report on the field monitoring of the performance of in-situ supplemental dehumidification systems in low energy, high performance, homes in a Hot-Humid climate. The purpose of this research project was to observe and compare the humidity control performance of new, single family, low energy, and high performance, homes. Specifically, the study sought to compare the interior conditions and mechanical systems operation between two distinct groups of houses, homes with a supplemental dehumidifier installed in addition to HVAC system, and homes without any supplemental dehumidification. The subjects of the study were ten single-family new construction homes in New Orleans, LA. Data logging equipment was installed at each home in 2012. Interior conditions and various end-use loads were monitored for one year. In terms of averages, the homes with dehumidifiers are limiting elevated levels of humidity in the living space. However, there was significant variation in humidity control between individual houses. An analysis of the equipment operation did not show a clear correlation between energy use and humidity levels. In general, no single explanatory variable appears to provide a consistent understanding of the humidity control in each house. Indoor humidity is likely due to all of the factors we have examined, and the specifics of how they are used by each occupant.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Low-Cost Evaluation of Energy Savings at the Community Scale, Fresno, California (Fact Sheet)

A new construction pilot community was constructed by builder-partner Wathen-Castanos Hybrid Homes (WCHH) based on a single occupied test house that was designed to achieve greater than 30% energy savings with respect to the House Simulation Protocols (Hendron, Robert; Engebrecht, Cheryn (2010). Building America House Simulation Protocols. Golden, CO: National Renewable Energy Laboratory.). Builders face several key problems when implementing a whole-house systems integrated measures package (SIMP) from a single test house into multiple houses. Although a technical solution already may have been evaluated and validated in an individual test house, the potential exists for constructability failures at the community scale. This report addresses factors of implementation and scalability at the community scale and proposes methodologies by which community-scale energy evaluations can be performed based on results at the occupied test house level. Research focused on the builder and trade implementation of a SIMP and the actual utility usage in the houses at the community scale of production. Five occupants participated in this community-scale research by providing utility bills and information on occupancy and miscellaneous gas and electric appliance use for their houses. IBACOS used these utility data and background information to analyze the actual energy performance of the houses. Verification with measured data is an important component in predictive energy modeling. The actual utility bill readings were compared to projected energy consumption using BEopt with actual weather and thermostat set points for normalization.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Sealed Crawl Spaces with Integrated Whole-House Ventilation in a Cold Climate, Ithaca, New York

"9One method of code-compliance for crawlspaces is to seal and insulate the crawlspace, rather than venting to the outdoors. However, codes require mechanical ventilation; either via conditioned supply air from the HVAC system, or a continuous exhaust ventilation strategy. As the CARB's building partner, Ithaca Neighborhood Housing Services, intended to use the unvented crawlspace in a recent development, CARB was interested in investigating a hybrid ventilation method that includes the exhaust air from the crawlspace as a portion of an ASHRAE 62.2 compliant whole-house ventilation strategy. This hybrid ventilation method was evaluated through a series of long-term monitoring tests that observed temperature, humidity, and pressure conditions through the home and crawlspace. Additionally, CARB worked with NREL to perform multi-point tracer gas testing on six separate ventilation strategies - varying portions of 62.2 required flow supplied by the crawlspace fan and an upstairs bathroom fan. The intent of the tracer gas testing was to identify effective Reciprocal Age of Air (RAoA), which is equivalent to the air change rate in well-mixed zones, for each strategy while characterizing localized infiltration rates in several areas of the home.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Conway Street Apartments, Greenfield, Massachusetts (Fact Sheet)

While single-family, detached homes account for 63% of households (EIA 2009); multi-family homes account for a very large portion of that remaining housing stock, and this fraction is growing. Through recent research efforts, CARB has been evaluating strategies and technologies that can make dramatic improvements in energy performance in multi-family buildings

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Multifamily Central Heat Pump Water Heaters, Davis, California

Although heat pump water heaters (HPWHs) have gained significant attention in recent years as a high efficiency electric water heating solution for single family homes, central HPWHs for commercial or multi-family applications are not as well documented in terms of measured performance and cost effectiveness. To evaluate this technology, the Alliance for Residential Building Innovation team monitored the performance of a 10.5 ton central HPWH installed on a student apartment building at the West Village Zero Net Energy Community in Davis, California. Monitoring data collected over a 16-month period were then used to validate a TRNSYS simulation model. The TRNSYS model was then used to project performance in different climates using local electric rates. Results of the study indicate that after some initial commissioning issues, the HPWH operated reliably with an annual average efficiency of 2.12 (Coefficient of Performance). The observed efficiency was lower than the unit's rated efficiency, primarily due to the fact that the system rarely operated under steady-state conditions. Changes in the system configuration, storage tank sizing, and control settings would likely improve the observed field efficiency. Modeling results suggest significant energy savings relative to electric storage water heating systems (typical annual efficiencies around 0.90) providing for typical simple paybacks of six to ten years without any incentives. The economics versus gas water heating are currently much more challenging given the current low natural gas prices in much of the country. Increased market size for this technology would benefit cost effectiveness and spur greater technology innovation.

30 DIRECT ENERGY CONVERSION↗

Building America Case Study: Multifamily Central Heat Pump Water Heaters, Davis, California

Although heat pump water heaters (HPWHs) have gained significant attention in recent years as a high efficiency electric water heating solution for single family homes, central HPWHs for commercial or multi-family applications are not as well documented in terms of measured performance and cost effectiveness. To evaluate this technology, the Alliance for Residential Building Innovation team monitored the performance of a 10.5 ton central HPWH installed on a student apartment building at the West Village Zero Net Energy Community in Davis, California. Monitoring data collected over a 16-month period were then used to validate a TRNSYS simulation model. The TRNSYS model was then used to project performance in different climates using local electric rates. Results of the study indicate that after some initial commissioning issues, the HPWH operated reliably with an annual average efficiency of 2.12 (Coefficient of Performance). The observed efficiency was lower than the unit's rated efficiency, primarily due to the fact that the system rarely operated under steady-state conditions. Changes in the system configuration, storage tank sizing, and control settings would likely improve the observed field efficiency. Modeling results suggest significant energy savings relative to electric storage water heating systems (typical annual efficiencies around 0.90) providing for typical simple paybacks of six to ten years without any incentives. The economics versus gas water heating are currently much more challenging given the current low natural gas prices in much of the country. Increased market size for this technology would benefit cost effectiveness and spur greater technology innovation.

ARBI↗

Building America Case Study: Standard- Versus High-Velocity Air Distribution in High-Performance Townhomes, Denver, Colorado

IBACOS investigated the performance of a small-diameter high velocity heat pump system compared to a conventional system in a new construction triplex townhouse. A ductless heat pump system also was installed for comparison, but the homebuyer backed out because of aesthetic concerns about that system. In total, two buildings, having identical solar orientation and comprised of six townhomes, were monitored for comfort and energy performance. Results show that the small-diameter system provides more uniform temperatures from floor to floor in the three-story townhome. No clear energy consumption benefit was observed from either system. The builder is continuing to explore the small-diameter system as its new standard system to provide better comfort and indoor air quality. The homebuilder also explored the possibility of shifting its townhome product to meet the U.S. Department of Energy Challenge Home National Program Requirements. Ultimately, the builder decided that adoption of these practices would be too disruptive midstream in the construction cycle. However, the townhomes met the ENERGY STAR Version 3.0 program requirements.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

Building America Case Study: Cost Analysis of Roof-Only Air Sealing and Insulation Strategies on 1-1/2 Story Homes in Cold Climates, Minneapolis, MN (Fact Sheet)

The External Thermal and Moisture Management System (ETMMS), typically seen in deep energy retrofits, is a valuable approach for the roof-only portions of existing homes, particularly the 1 1/2-story home. It is effective in reducing energy loss through the building envelope, improving building durability, reducing ice dams, and providing opportunities to improve occupant comfort and health.

1 1/2-STORY HOUSE↗

Building America Case Study: Standard- Versus High-Velocity Air Distribution in High-Performance Townhomes, Denver, Colorado

IBACOS investigated the performance of a small-diameter high-velocity heat pump system compared to a conventional system in a new construction triplex townhouse. A ductless heat pump system also was installed for comparison, but the homebuyer backed out because of aesthetic concerns about that system. In total, two buildings, having identical solar orientation and comprised of six townhomes, were monitored for comfort and energy performance.

air distribution↗