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Validation of a Hot Water Distribution Model Using Laboratory and Field Data

Description: Characterizing the performance of hot water distribution systems is a critical step in developing best practice guidelines for the design and installation of high performance hot water systems. Developing and validating simulation models is critical to this effort, as well as collecting accurate input data to drive the models. In this project, the ARBI team validated the newly developed TRNSYS Type 604 pipe model against both detailed laboratory and field distribution system performance data. Validation efforts indicate that the model performs very well in handling different pipe materials, insulation cases, and varying hot water load conditions. Limitations of the model include the complexity of setting up the input file and long simulation run times. In addition to completing validation activities, this project looked at recent field hot water studies to better understand use patterns and potential behavioral changes as homeowners convert from conventional storage water heaters to gas tankless units. Based on these datasets, we conclude that the current Energy Factor test procedure overestimates typical use and underestimates the number of hot water draws. This has implications for both equipment and distribution system performance. Gas tankless water heaters were found to impact how people use hot water, but the data does not necessarily suggest an increase in usage. Further study in hot water usage and patterns is needed to better define these characteristics in different climates and home vintages.
Date: July 1, 2013
Creator: Backman, C. & Hoeschele, M.
Partner: UNT Libraries Government Documents Department

Air-to-Water Heat Pumps With Radiant Delivery in Low-Load Homes

Description: Space conditioning represents nearly 50% of average residential household energy consumption, highlighting the need to identify alternative cost-effective, energy-efficient cooling and heating strategies. As homes are better built, there is an increasing need for strategies that are particularly well suited for high performance, low load homes. ARBI researchers worked with two test homes in hot-dry climates to evaluate the in-situ performance of air-to-water heat pump (AWHP) systems, an energy efficient space conditioning solution designed to cost-effectively provide comfort in homes with efficient, safe, and durable operation. Two monitoring projects of test houses in hot-dry climates were initiated in 2010 to test this system. Both systems were fully instrumented and have been monitored over one year to capture complete performance data over the cooling and heating seasons. Results are used to quantify energy savings, cost-effectiveness, and system performance using different operating modes and strategies. A calibrated TRNSYS model was developed and used to evaluate performance in various climate regions. This strategy is most effective in tight, insulated homes with high levels of thermal mass (i.e. exposed slab floors).
Date: December 1, 2013
Creator: Backman, C.; German, A.; Dakin, B. & Springer, D.
Partner: UNT Libraries Government Documents Department

Sonoma House: Monitoring of the First U.S. Passive House Retrofit

Description: The Sonoma Deep Retrofit is a single-story deep retrofit project in the marine climate of Sonoma, California. The design was guided by Passive House principles which promote the use of very high levels of wall, ceiling, and floor insulation along with tight envelope construction to maintain a comfortable indoor environment with little or no need for conventional heating or cooling.
Date: December 1, 2012
Creator: German, A.; Weitzel, B.; Backman, C.; Hoeschele, M. & Dakin, B.
Partner: UNT Libraries Government Documents Department

Super Energy Efficiency Design (S.E.E.D.) Home Evaluation

Description: This report describes the results of evaluation by the Alliance for Residential Building Innovation (ARBI) Building America team of the 'Super Energy Efficient Design' (S.E.E.D) home, a 1,935 sq. ft., single-story spec home located in Tucson, AZ. This prototype design was developed with the goal of providing an exceptionally energy efficient yet affordable home and includes numerous aggressive energy features intended to significantly reduce heating and cooling loads such as structural insulated panel (SIP) walls and roof, high performance windows, an ERV, an air-to-water heat pump with mixed-mode radiant and forced air delivery, solar water heating, and rooftop PV. Source energy savings are estimated at 45% over the Building America B10 Benchmark. System commissioning, short term testing, long term monitoring and detailed analysis of results was conducted to identify the performance attributes and cost effectiveness of the whole house measure package.
Date: December 1, 2012
Creator: German, A.; Dakin, B.; Backman, C.; Weitzel, E. & Springer, D.
Partner: UNT Libraries Government Documents Department

Feasibility Study: Ductless Hydronic Distribution Systems with Fan Coil Delivery

Description: The primary objectives of this study are to estimate potential energy savings relative to conventional ducted air distribution, and to identify equipment requirements, costs, and barriers with a focus on ductless hydronic delivery systems that utilize water-to-air terminal units in each zone. Results indicate that annual heating and cooling energy use can be reduced by up to 27% assuming replacement of the conventional 13 SEER heat pump and coil with a similarly rated air-to-water heat pump.
Date: July 1, 2012
Creator: Springer, D.; Dakin, B. & Backman, C.
Partner: UNT Libraries Government Documents Department

West Village Community: Quality Management Processes and Preliminary Heat Pump Water Heater Performance

Description: West Village, a multi-use project underway at the University of California Davis, represents a ground-breaking sustainable community incorporating energy efficiency measures and on-site renewable generation to achieve community-level Zero Net Energy (ZNE) goals. The project when complete will provide housing for students, faculty, and staff with a vision to minimize the community's impact on energy use by reducing building energy use, providing on-site generation, and encouraging alternative forms of transportation. This focus of this research is on the 192 student apartments that were completed in 2011 under Phase I of the West Village multi-year project. The numerous aggressive energy efficiency measures implemented result in estimated source energy savings of 37% over the B10 Benchmark. There are two primary objectives of this research. The first is to evaluate performance and efficiency of the central heat pump water heaters as a strategy to provide efficient electric water heating for net-zero all-electric buildings and where natural gas is not available on site. In addition, effectiveness of the quality assurance and quality control processes implemented to ensure proper system commissioning and to meet program participation requirements is evaluated. Recommendations for improvements that could improve successful implementation for large-scale, high performance communities are identified.
Date: November 1, 2012
Creator: Dakin, B.; Backman, C.; Hoeschele, M. & German, A.
Partner: UNT Libraries Government Documents Department