What Are Phase Change Materials, and how do they Work?
As we mentioned in the introduction, phase change materials are elements that can change from solid to liquid and liquid to solid. For home construction purposes, certain substances with carefully selected melting points are used to store and release heat to affect and control the temperature within a home.
Without getting too scientific, the necessary process behind how phase change materials work goes as follows:
- The absorption of heat melts a given material or element at a given temperature.
- During the melting process, the material will absorb heat from the environment, thus causing the interior space to become cooler.
- As the temperature drops, the material then re-solidifies, releases heat, and allows the space to become warmer.
- Materials with a phase change temperature similar to comfortable household temperatures could be stored in what builders call "insulated buffers." The heat or cold released during phase change could remain available for use later - when temperature fluctuations would usually have homeowners turn up or down the thermostat.
Many people don't realize that phase change materials will not change during the process of change. The most commonly cited example is that when ice is melting, the temperature will stay steady at 32 degrees Fahrenheit while ice is still present. The possible use of phase change materials for homes hinges on the opportunity to store that generated but latent heat for release later.
Potential Benefits of Phase Change Building Materials for Sustainable Homes
As we have stated above, whenever a material melts or solidifies, it will absorb or release energy. Materials that will melt or solidify at room temperatures can potentially contribute to the regulation of home temperature. The most common phase change materials studied for sustainable home products are paraffin waxes and certain fatty acids.
In essence, a paraffin wax that melts at 73 degrees Fahrenheit could offer similar benefits to thermal mass. During warm afternoons, this wax could melt, and the latent energy from that warming process could be stored for release during cooler evenings. With modern-day technology, the main benefit is that Nano-particles of paraffin wax could be incorporated into lightweight building materials such as plywood or drywall.
Phase change materials could offer the same benefits as massive adobe, brick, or rock walls without the cost and added weight these traditional vernacular construction methods entail.
An Interesting Example of Phase Change Materials
Phase change materials present an exciting opportunity for sustainable building strategies and methodologies. The release of energy during melting or solidification is an entirely natural form of energy. It could potentially replace a part of our reliance on fossil fuel sources of energy for our homes. Unfortunately, most phase change building materials are still being studied in laboratories and universities around the world.
