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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. Thu . "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 = {Thu Jun 23 00:00:00 EDT 2016},
month = {Thu Jun 23 00:00:00 EDT 2016}
}

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