skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems

Abstract

Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperature modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7% after implementing the demand control technique, 2% after implementing temperature modulation, and 15% after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating andmore » cooling interactions included, the estimated annual cost savings were 8%, 1%, and 14% for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.« less

Authors:
 [1];  [1];  [1];  [1]
  1. The Levy Partnership, Inc., New York, NY (United States). Advanced Residential Integrated Energy Solutions
Publication Date:
Research Org.:
The Levy Partnership, Inc., New York, NY (United States). Advanced Residential Integrated Energy Solutions
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Building Technologies Office (EE-5B)
OSTI Identifier:
1263778
Report Number(s):
DOE/GO-102016-4703
7429
DOE Contract Number:
AC36-08GO28308
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; residential; Residential Buildings; ARIES; Building America; DHW; domestic hot water; multifamily; recirculating pump controls; demand control; temperature modulation; central domestic hot water systems

Citation Formats

Dentz, Jordan, Ansanelli, Eric, Henderson, Hugh, and Varshney, Kapil. Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems. United States: N. p., 2016. Web. doi:10.2172/1263778.
Dentz, Jordan, Ansanelli, Eric, Henderson, Hugh, & Varshney, Kapil. Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems. United States. doi:10.2172/1263778.
Dentz, Jordan, Ansanelli, Eric, Henderson, Hugh, and Varshney, Kapil. 2016. "Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems". United States. doi:10.2172/1263778. https://www.osti.gov/servlets/purl/1263778.
@article{osti_1263778,
title = {Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems},
author = {Dentz, Jordan and Ansanelli, Eric and Henderson, Hugh and Varshney, Kapil},
abstractNote = {Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperature modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7% after implementing the demand control technique, 2% after implementing temperature modulation, and 15% after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating and cooling interactions included, the estimated annual cost savings were 8%, 1%, and 14% for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.},
doi = {10.2172/1263778},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 6
}

Technical Report:

Save / Share:
  • Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperaturemore » modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7% after implementing the demand control technique, 2% after implementing temperature modulation, and 15% after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating and cooling interactions included, the estimated annual cost savings were 8%, 1%, and 14% for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.« less
  • This report reviews the research conducted in connection with a project to apply psychological theory and procedures to the problems of encouraging residential energy conservation. A major part of the project involved surveys of residents' energy-related attitudes. The best (and only consistent) attitudinal predictor of residents' actual energy consumption was their attitude about thermal comfort. A number of other attitudes that could conceivably have been related to consumption, such as attitudes about the reality of the crisis, were not found to be related to consumption. Another major focus of the project was on the effectiveness of feedback (that is, givingmore » residents information about their energy use) as an aid to residents' conservation efforts. A series of experiments demonstrated that frequent, credible energy-consumption feedback, coupled with encouragement to adopt a reasonable but difficult energy-conservation goal, could facilitate conservation. However, these studies also demonstrated that residents could not be given just any kind of information about their energy use as feedback and that even proper feedback would not lead to conservation in all households. Conditions that are crucial for the success of feedback as a conservation aid are discussed. Other studies conducted by the project looked at the effect on energy consumption of (1) a device to reduce air-conditioning waste by signalling when it is cool outside, (2) an automatic multi-setback thermostat, and (3) utility companies' average payment plans. A survey of residents' knowledge of their energy use also was conducted. 23 references.« less
  • The Long Island Lighting Company (LILCO) serves Long Island and a small section of Queens, New York, with electricity and gas. The company has under construction one nuclear-powered, 830-MW electric generating plant, the Shoreham, scheduled to come on-line late in 1978; in addition, LILCO has made application to construct two new nuclear plants in the town of Riverhead in Suffolk County, Long Island; Jamesport I and Jamesport II, each with a capacity of 1150 MW are planned to come on-line in 1982 and 1984, respectively. LILCO's justification for these two new plants is based on the system required to meetmore » the loads which, according to their forecasts, will occur during the period 1975-1995. The projection of the peak electric demand and the yearly consumption of electricity and the method of forecasting (exponential smoothing analysis) by LILCO are analyzed. An intensive energy conservation program coupled with a modest solar energy system for domestic hot water and space heating and cooling is shown to have the potential of reducing the normal loads to the extent that not only could the Jamesport I and II plants be cancelled, but also that the completion of the Shoreham plant could be delayed. The potential of the wind energy available over Long Island is shown to exceed all of its energy requirements for the next twenty years. On-site total energy systems and the use of solid waste for fuel are cited as two additional measures to further reduce the need for raw source energy (fossil fuel or nuclear), for central electric generating plants. (MCW)« less