Van D Baxter

Nearly-zero energy buildings

It is more than well-established that heating, cooling, and ventilation of buildings together represent one of the most dominant shares of the world’s total energy use. Building codes and/or private or government incentive programs in many countries already require or promote reduced energy use in current and future buildings. With their very high energy performance, nearly-zero energy buildings (nZEB) are setting new standards for building design and operation. These, over time, may be instrumental in minimizing buildings energy use and carbon footprint. nZEBs are characterized, first, by their very efficient thermal envelopes which result in a very low energy requirement for space heating and cooling. Second, a significant extent of their energy needs can be offset by renewable energy resources, including that produced on-site or nearby. This special issue presents 15 articles that have been broadly classified into four categories, all focused on exploring issues related with nZEB: indoor environment and occupant behavior, design and renovation, measurement and simulation of the performance of nZEB and their systems, and legislation and standardization.

Ground Source Integrated Heat Pump (GS-IHP) Development

Between October 2008 and May 2013 ORNL and ClimateMaster, Inc. (CM) engaged in a Cooperative Research and Development Agreement (CRADA) to develop a groundsource integrated heat pump (GS-IHP) system for the US residential market. A initial prototype was designed and fabricated, lab-tested, and modeled in TRNSYS (SOLAR Energy Laboratory, et al, 2010) to predict annual performance relative to 1) a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of air-source heat pump (ASHP) and resistance water heater) and 2) a state-of-the-art (SOA) two-capacity ground-source heat pump with desuperheater water heater (WH) option (GSHPwDS). Predicted total annual energy savings, while providing space conditioning and water heating for a 2600 ft{sup 2} (242 m{sup 2}) house at 5 U.S. locations, ranged from 52 to 59%, averaging 55%, relative to the minimum efficiency suite. Predicted energy use for water heating was reduced 68 to 78% relative to resistance WH. Predicted total annual savings for the GSHPwDS relative to the same baseline averaged 22.6% with water heating energy use reduced by 10 to 30% from desuperheater contributions. The 1st generation (or alpha) prototype design for the GS-IHP was finalized in 2010 and field test samples were fabricated for testing by CM and by ORNL. Two of the alpha units were installed in 3700 ft{sup 2} (345 m{sup 2}) houses at the ZEBRAlliance site in Oak Ridge and field tested during 2011. Based on the steady-state performance demonstrated by the GS-IHPs it was projected that it would achieve >52% energy savings relative to the minimum efficiency suite at this specific site. A number of operational issues with the alpha units were identified indicating design changes needed to the system before market introduction could be accomplished. These were communicated to CM throughout the field test period. Based on the alpha unit test results and the diagnostic information coming from the field test experience, CM developed a 2nd generation (or beta) prototype in 2012. Field test verification units were fabricated and installed at the ZEBRAlliance site in Oak Ridge in May 2012 and at several sites near CM headquarters in Oklahoma. Field testing of the units continued through February 2013. Annual performance analyses of the beta unit (prototype 2) with vertical well ground heat exchangers (GHX) in 5 U.S. locations predict annual energy savings of 57% to 61%, averaging 59% relative to the minimum efficiency suite and 38% to 56%, averaging 46% relative to the SOA GSHPwDS. Based on the steady-state performance demonstrated by the test units it was projected that the 2nd generation units would achieve ~58% energy savings relative to the minimum efficiency suite at the Zebra Alliance site with horizontal GHX. A new product based on the beta unit design was announced by CM in 2012 – the Trilogy 40® Q-mode™ (http://cmdealernet.com/trilogy_40.html). The unit was formally introduced in a March 2012 press release (see Appendix A) and was available for order beginning in December 2012.

Research and Development Roadmap for Water Heating Technologies

Although water heating is an important energy end-use in residential and commercial buildings, efficiency improvements in recent years have been relatively modest. However, significant advancements related to higher efficiency equipment, as well as improved distribution systems, are now viable. DOE support for water heating research, development and demonstration (RD&D) could provide the impetus for commercialization of these advancements.

Commercial Integrated Heat Pump with Thermal Storage --Demonstrate Greater than 50% Average Annual Energy Savings, Compared with Baseline Heat Pump and Water Heater (Go/No-Go) FY16 4th Quarter Milestone Report

For this study, we authored a new air source integrated heat pump (AS-IHP) model in EnergyPlus, and conducted building energy simulations to demonstrate greater than 50% average energy savings, in comparison to a baseline heat pump with electric water heater, over 10 US cities, based on the EnergyPlus quick-service restaurant template building. We also assessed water heating energy saving potentials using ASIHP versus gas heating, and pointed out climate zones where AS-IHPs are promising.

IEA HPP Annex 41 Cold Climate Heat Pumps: Task 1 Report Literature and Technology Review United States - ORNL/TM-2013/472

During the mid-1970s, following the first oil embargo, heat pumps became of great interest to northern U. S. electric power companies, particularly for those experiencing large peak demands during the heating season, as shortages of natural gas and oil led to increased usage of direct electric heating. Air-source heat pumps (ASHP), given their wider market presence relative to other heat pump types, almost universal applicability, and inherent efficiency and capacity issues at cold outdoor temperatures were of primary interest as an electrical heating system alternative at that time. ASHPs based on the simple vapor compression cycle suffer both heating capacity (output) and efficiency (coefficient of performance or COP) degradation as the outdoor ambient temperature drops. At the same time, building heat demand is increasing so ASHPs require a supplemental heating source – usually direct electric resistance heating elements to bridge the gap between the building heat demand and the ASHP heating output. This feature causes lower seasonal performance and limits peak electric demand reduction potential leading to limited acceptance of ASHPs in areas that experience large numbers of hours at cold temperatures (loosely defined as ≤-7°C for purposes of Annex 41). A primary criterion for ASHPs to achieve good seasonal performance in cold areas is achieving high heating output at low ambient temperatures so as to minimize reliance on supplemental heat sources and maximize the overall system heating seasonal performance factor (HSPF or SPFh).

Analysis of highly-efficient electric residential HPWHs

A scoping level analysis was conducted to identify electric HPWH concepts that have the potential to achieve or exceed 30% source energy savings compared to a gas tankless water heater (GTWH) representative of the type represented in version 0.9.5.2 beta of the BEopt software developed by the National Renewable Energy Laboratory. The analysis was limited to evaluation of options to improve the energy efficiency of electric HPWH product designs currently on the market in the US. The report first defines the baseline GTWH system and determines its efficiency (source-energy-based adjusted or derated EF of ~0.71). High efficiency components (compressors, pumps, fans, heat exchangers, etc.) were identified and applied to current US HPWH products and analyzed to determine the viability of reaching the target EF. The target site-based energy factor (EF) required for an electric HPWH necessary to provide 30% source energy savings compared to the GTWH baseline unit is then determined to be ~3.19.

Integrated Heat Pump (IHP) System Development - Air-Source IHP Control Strategy and Specifications and Ground-Source IHP Conceptual Design

The integrated heat pump (IHP), as one appliance, can provide space cooling, heating, ventilation, and dehumidification while maintaining comfort and meeting domestic water heating needs in near-zero-energy home (NZEH) applications. In FY 2006 Oak Ridge National Laboratory (ORNL) completed development of a control strategy and system specification for an air-source IHP. The conceptual design of a ground-source IHP was also completed. Testing and analysis confirm the potential of both IHP concepts to meet NZEH energy services needs while consuming 50% less energy than a suite of equipment that meets current minimum efficiency requirements. This report is in fulfillment of an FY06 DOE Building Technologies (BT) Joule Milestone.

Heat Pump Technology: Responding to New Opportunities

This paper provides an update on advanced heat pump research and development activities in the United States and Canada. Under the general area of vapor compression technology a major need toward which these research programs are directed is the development of viable alternatives to HCFC-22 for heat pump and air-conditioning applications. The HCFC phaseout provides an opportunity to develop advanced refrigeration equipment for the new refrigerants which has higher energy efficiency than current heat pump systems. Programs are underway in both industry and government laboratories and are characterized by close collaboration between major manufacturers and government agencies to plan and execute the research. Under the general area of thermally activated heat pump technology, there are several cooperative early-commercialization activities being conducted on gas-fired heat pumps and chillers by government, HVAC industry, and gas utility organizations.

Vapor compression heat pump system field tests at the tech complex

The Tennessee Energy Conservation In Housing (TECH) complex has been utilized since 1977 as a field test site for several novel and conventional heat pump systems for space conditioning and water heating. Systems tested include the Annual Cycle Energy System (ACES), solar assisted heat pumps (SAHP) both parallel and series, two conventional air‐to‐air heat pumps, an air‐to‐air heat pump with desuperheater water heater, and horizontal coil and multiple shallow vertical coil ground‐coupled heat pumps (GCHP). A direct comparison of the measured annual performance of the test systems was not possible. However, a cursory examination revealed that the ACES had the best performance, however, its high cost makes it unlikely that it will achieve wide‐spread use. Costs for the SAHP systems are similar to those of the ACES but their performance is not as good. Integration of water heating and space conditioning functions with a desuperheater yielded significant efficiency improvement at modest cost. The GCHP systems...