Phase Change Materials – The “New Old” Thermal Mass Solution

turko with hat

by Turko Semmes

In the past, I have written before about Passive Solar Solutions for buildings. And still they are an important way to reduce energy costs and increase comfort levels. There are four components that must be considered when applying passive solar solutions to a project. They are Orientation, Ventilation, Insulation, and Mass (OVIM). Each part of the solution is used in different ways depending on the climate where the building is being built as well as certain site, budget and human factors. But by applying these applications appropriately, the building’s energy use can be greatly reduced. The comfort levels can be raised even in severe climate zones, sometimes at little extra cost.

Today, I want to talk about Mass, sometimes known as Thermal Mass. In particular, let’s discuss Phase Change Materials (PCM’s). The Thermal Mass role is to act as a battery to moderate the temperature of the home through the daily and seasonal cycle changes.

There are two applications of mass. One is direct gain where the sun strikes the material directly – think Trombe Wall systems.

The other and more common application is indirect gain. This is where the temperature of the mass is affected by the room temperature – think all surfaces in the building. We try to incorporate standard high mass materials into buildings to achieve this, but it is not always practical. Some of these materials are concrete in the floor, walls and counters. Also used are extra layers of drywall, fireplace facings, etc.

But for years, we in the industry have thought it would be super to have a material that can store more heat than its actual weight or volume. Now that material is here and it’s called Phase Change Materials (PCM). PCM’s can store 5 to 14 times more heat per unit volume than conventional storage materials such as water, masonry or rock. They do this by changing from a liquid to a solid (much like Freon does in heat pump/air conditioning systems). The trick has been to find a way to incorporate them into buildings in a format that can be standard for all buildings.

Now, the National Gypsum Company in partnership with BASF has ThermalCORE PCMmanufactured a drywall that has small capsules – beads of phase change material within the board. The drywall is installed and finished in the same ordinary way. The only extra cost is the material itself. But, don’t jump up and run down to Home Depot or Lowes. This material is in the economic and marketing development stages. However, I do have some samples, and they are performing quite well, as specified.

Soon, this material will give your energy analyst another tool to help design your building to be more energy efficient and comfortable. All without adding additional systems, complications or maintenance. Since drywall is used on most buildings, one can place it strategically to achieve the comfort and energy savings desired. This is just one more reason Passive Solar Solutions should be applied to their maximum potential before any active or complicated systems are considered.

Phase Change Materials for
Building Applications