Domestic Hot Water Event Schedule Generator

Technology Marketing SummaryResidential hot water use in the United States accounts for 14-25% of all the energy consumed in a home. With the rise of more advanced water heating systems, more advanced monitoring and testing of hot water applications is crucial to ensure energy efficiency. Previous technologies make simplifying assumptions about hot water usage that neglect to take into account complex occupant behavior. This can lead hot water system designers to overestimate their energy savings by up to 20%. National Renewable Energy Laboratory (NREL) scientists have designed the Domestic Hot Water Event Scheduler, which generates sophisticated hot water use profiles to realistically model the behavior of various types of building occupants, thereby more accurately predicting the energy savings resulting from hot water system improvements. DescriptionThe Domestic Hot Water Event Scheduler is a novel, realistic simulation of hot water usage in residential buildings. This software creates comprehensive hot water event schedules based on sporadic and unpredictable occupant behavior. These probabilistic schedules are then combined with hot water system models or standard test protocols to analyze the energy savings of previous generation systems and new technologies.

The amount of energy savings for advanced residential hot water systems is greatly dependent on the occupant use patterns. This software generates and allows users to customize hot water profiles which take into account vacation periods, weekday/weekend effects, geographic locations, seasonality, and individual water fixture use. Additionally, the software generates data on hot water use start times, duration, flow rates, event clusters, and variability in order to build more robust water use profiles to more precisely determine energy savings.

The application has been successfully incorporated into at least five major projects which have proven the Domestic Hot Water Event Scheduler to be a useful tool, eliminating errors of up to 20% in previous energy usage models. Benefits

• Provides a more accurate estimation of energy savings based on realistic profiles of hot water usage
• Allows users to specify number of bedrooms, geographic location, hot or mixed water, and time steps
• Takes into account vacation periods, weekday/weekend effects, geographic locations, seasonality, individual water fixture use, start times, durations, flow rates, event clusters, and daily variability of hot water usage

Applications and Industries

• Energy efficiency planning and testing for builders, plumbers, contractors, retrofitters, sustainability consultants, or researchers
• Testing, standardizing, rating, and certifying legacy and new hot water distribution systems

Technology Status

Technology ID	Development Stage	Availability	Published	Last Updated
Copyright © 2010 Alliance for Sustainable Energy, LLC. All rights reserved.	Development - Algorithm development, coding, and initial user interface are complete. Ongoing improvements include additional user inputs and options, and program speed enhancements.	Available - Currently this software is available for non-commercial use on the U.S. Department of Energy’s Building America website, http://www1.eere.energy.gov/buildings/building_america/perf_analysis.html. Please contact the NREL Commercialization and Technology Transfer Office for information concerning a commercial license to use the software.	06/24/2010	07/28/2010