Phase Change Material Subdues Hot/Cold Calls

At an outpatient facility, trial implementation of phase change material showcases latent heat storage that improves occupant comfort.

By Richie Stever, LEED AP, CHFM
From the February 2020 Issue

The University of Maryland Marlene and Stewart Greenebaum Comprehensive Cancer Center provides outpatient care for cancer patients in a 25,000-square-foot, state-of-the-art facility named the Roslyn and Leonard Stoler Pavilion (Outpatient Cancer Care, 2019)¹. The infusion/chemotherapy treatment portion of the Stoler Pavilion is a 7,500 square foot extension of the main lobby of the University of Maryland Medical Center (UMMC). This area features large floor to ceiling storefront windows, 10-foot ceilings, and a metal pan deck that is 10 feet above the uninsulated drop ceiling. The heating and air conditioning consisted of digitally controlled variable air volume (VAV) boxes with reheat coils and baseboard heat.

Phase Change Material
The phase change material was installed above ceiling tiles over the outpatient facility space. Each sheet of the product weighs approximately eight pounds. The UMMC facilities team installed the materials. (Photos: Richie Stever of UMMC)

For years the facilities staff here received hot calls in the summer and cold calls in the winter. The facilities staff would adjust the discharge temperature of the central air handlers to push colder air to the space; they would adjust the setpoints of the space; and they even closed dampers elsewhere on the floor to push more volume to the space. No matter what adjustments they made to the heating and air conditioning system, the patients, staff, and visitors were never at a comfortable temperature. The patients in the infusion area wear thin gowns and sit next to the perimeter windows for 8-10 hours a day and some receive treatment multiple times a week.

In the summer of 2018, as director of operations and maintenance for UMMC, I learned about phase change material (PCM) heat storage at the U.S. Department of Energy’s Better Buildings Summit in Cleveland, OH. According to Coleman-Sanders (2015)² there are two main types of thermal energy storage—sensible heat storage (SHS) and latent heat storage (LHS). Sensible heat storage is the most common method for storing heat, which heats the material such as water, rock, soil, etc. to the stored temperature. Latent heat storage however, stores energy through the phase transition from liquid-solid and/or solid-solid using water/ice, salt hydrates, paraffin, or polyalcohol. PCM uses latent heat storage, and it essentially absorbs (melts) or releases (freezes) large amounts of latent heat when it changes physical state at a given temperature.

After learning about PCMs, UMMC decided to try Insolcorp’s PCM product to address the temperature swings experienced in the Stoler Pavilion. This material was chosen because it was non-toxic, class A plenum fire rated, and stored 100 BTUs per square foot. After discussing the application with the Insolcorp staff, the appropriate material was 2’x4′ sheets of 71°F material that would simply be laid on top of the ceiling tiles over approximately 70% of the space. One hundred percent coverage was not possible given the number of sprinkler heads, speakers, lights, and diffusers already in the ceiling. The direction was to install the PCM mats ensuring that the ceiling mains and tees and not just the ceiling tile supported it. After all, each sheet of PCM weighs approximately eight pounds.

The temperature above and below the ceiling in two separate locations of the Stoler Pavilion were recorded for two weeks prior to the installation in order to prove the efficacy of the material. In October 2018, there were 10 UMMC facilities team members installing the material, and this took 2.5 hours. Prior to the installation, the UMMC facilities team was receiving an average of 2.58 hot/cold calls per month from the Stoler Pavilion. Since the installation, the hot/cold calls have been reduced to zero.

This phase change installation was focused on patient and staff satisfaction, so energy consumption was not recorded, but if the 7,000 square feet of material holds 100btu/sf, then UMMC is avoiding significant electricity expenses per month.


¹ Outpatient Cancer Care. (2019). Providing one-stop cancer care. University of Maryland Medical System.
² Coleman-Sanders, M. (2015). Green Building and Phase Change Materials: Characteristics, Energy Implications and Environmental Impacts. New York: Nova Science Publishers, Inc. ISBN: 978-1-63482-702-7

University of Maryland Medical Center (UMMC)Stever is director of operations and maintenance for the University of Maryland Medical Center (UMMC) downtown and midtown campuses, which include 3.5 million square feet. He is a LEED accredited professional, a Certified Healthcare Facility Manager, and a Certified Life Safety Specialist for Healthcare. Stever is an active member in the American College of Healthcare Executives, the National Fire Protection Association, the American Society for Healthcare Engineering, the Chesapeake Area Society of Healthcare Engineering, and is the former co-chair of the Healthcare Steering Committee of the Better Buildings Alliance.

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