Mirian Velay-Lizancos, a Purdue assistant professor of civil engineering, has developed a process that improves upon the traditional method to incorporate phase change materials into construction materials. Credit: Purdue University photo/John UnderwoodResearchers in the lab of Mirian Velay-Lizancos at Purdue University have developed a scalable and automatable process that enhances the introduction of phase change materials (PCMs) into building construction. This innovative process, which can be easily automatized and incorporated into the production chain of bricks, concrete panels and drywall, will help reduce the energy consumption in their manufacture, as well as the overall carbon footprint of heating and cooling homes.
PCMs are applied to doors, exterior walls, foundations, roofs and windows, part of a building’s envelope that form a barrier between indoors and outdoors. The thermal properties of building envelopes are crucial for a building’s energy consumption, and incorporating PCMs lowers the impact of external temperature changes to the indoor environment since they convert changes in thermal energy into phase changes by transitioning from a solid into a liquid, or the opposite.
In reducing energy consumption, PCMs also bring down carbon dioxide emissions as well as operational costs, in addition to the water permeability of building materials. As Velay-Lizancos has said, “Increasing the heat storage capabilities of building envelopes would reduce the effect of temperature fluctuations in a building. This would increase the thermal comfort of the building and decrease energy consumption, carbon dioxide emissions and related economic costs of heating and cooling.”
As reported Construction and Building Materials [Lopez-Aias et al. Constr. Build. Mater. (2023) DOI: 10.1016/j.conbuildmat.2023.130621], this new process improves the standard approach to incorporating PCMs such as paraffin, esters and salt hydrates into construction materials. It also shows a new method for incorporating PCMs into mortars without reducing their strength. It uses liquid immersion and a vacuum system to incorporate PCMs after construction materials have already been formed, enhancing their strength and durability, as well thermal inertia.
The approach introduces the PCM into the layer of the material closest to the material's surface, so there will be more in contact with the external surfaces of the building envelope. The process also drives the PCM material into the capillary pores through the vacuum without leakage, even when the final composite experienced high temperatures.
On testing, cement mortars with different ratios and initial porosity levels, with the PCMs being incorporated into the mortars for three different vacuum periods, an increase in the thermal inertia of 24% and over a 22% of increase in the compressive strength was demonstrated. The team hope to develop a full-scale prototype to allow them to use cameras and sensors to visualize the thermal performance of the building envelope. This will provide hard data and a way to assess its effectiveness.
“Increasing the heat storage capabilities of building envelopes would reduce the effect of temperature fluctuations in a building. This would increase the thermal comfort of the building and decrease energy consumption, carbon dioxide emissions and related economic costs of heating and cooling.”Mirian Velay-Lizancos