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Title: Potential Energy Savings Due to Phase Change Material in a Building Wall Assembly: An Examination of Two Climates

Potential Energy Savings Due to Phase Change Material in a Building Wall Assembly: An Examination of Two Climates Phase change material (PCM), placed in an exterior wall, alters the temperature profile within the wall and thus influences the heat transport through the wall. This may reduce the net energy transport through the wall via interactions with diurnal temperature swings in the external environment or reduce the electricity needed to meet the net load through the wall by shifting the time of the peak load to a time when the cooling system operates more efficiently. This study covers a broad range of parameters that can influence the effectiveness of such a merged thermal storage-thermal insulation system. These parameters included climate, PCM location within the wall, amount of PCM, midpoint of the PCM melting and freezing range relative to the indoor setpoint temperature, temperature range over which phase change occurs, and the wall orientation. Two climates are investigated using finite difference and optimization analyses: Phoenix and Baltimore, with two utility rate schedules. Although potential savings for a PCM with optimized properties were greater when the PCM was concentrated near the inside wall surface, other considerations described here lead to a recommendation for a full-thickness application. An examination of the temperature distribution within the walls also revealed the potential for this more » system to reduce the amount of energy transported through the wall framing. Finally, economic benefits can exceed energy savings when time-of-day utility rates are in effect, reflecting the value of peak load reductions for the utility grid. « less
Authors: ;
Publication Date:
OSTI Identifier:OSTI ID: 1038077
Report Number(s):ORNL/TM-2012/6
BT0304020; CEBT314; TRN: US201208%%543
DOE Contract Number:DE-AC05-00OR22725
Resource Type:Technical Report
Research Org:Oak Ridge National Laboratory (ORNL); Building Technologies Research and Integration Center
Sponsoring Org:EE USDOE - Office of Energy Efficiency and Renewable Energy (EE)
Country of Publication:United States
Language:English
Subject: 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 29 ENERGY PLANNING, POLICY AND ECONOMY; 36 MATERIALS SCIENCE; CLIMATES; COOLING SYSTEMS; ECONOMICS; ELECTRICITY; FREEZING; INDOORS; MELTING; NET ENERGY; OPTIMIZATION; ORIENTATION; PEAK LOAD; PHASE CHANGE MATERIALS; POTENTIAL ENERGY; RECOMMENDATIONS; SCHEDULES; TEMPERATURE DISTRIBUTION; TRANSPORT