This Small Business Innovation Research Phase I project will incorporate thermochromic pigments into inorganic coatings to be used as a replacement for colored clay-coatings on roofing shingle granules. This novel inorganic coating will turn dark in low temperatures and light at higher temperatures, to absorb solar heat in the winter and reflect solar radiation in the summer, thereby increasing the energy efficiencies of buildings. The thermochromic roofing materials will be resistant to UV radiation and chemical degradation. The thermochromic coating can also be used as durable thermochromic paint for existing low-slope roofs. In Phases I and II, Sommer Materials Research, Inc. will demonstrate the stability of the thermochromic material as a granule coating. Mechanical properties, UV stability, chemical stability and weatherability of the thermochromic coating will be investigated. Various tests will be done in different climate zones to test the durability of the material ranging from mild to severe weather conditions. Sommer Materials will collaborate with commercial shingle manufacturers to incorporate the inorganic coatings on their shingle products.
The broader impact/commercial potential of this project will be focused on reducing heating and cooling needs of buildings and homes by >30% average annually by using these novel thermochromic coatings. Buildings consume almost 40% of the energy of the world. The global demand for air conditioning systems have skyrocketed in developing countries world-wide and significantly increased energy demands. Over 50% of the world's population lives in urban areas and the percentage is substantially increasing, thus creating the "heat-island" effect in cities, with daytime temperatures in cities 2-5oC higher than in the outlying rural areas. Using thermochromic roofs on buildings would help mitigate these summer heat islands by reducing energy consumption for summer cooling and by improving urban air quality.
Buildings consume almost 40% of the energy of the world. The global demand for air conditioning systems has skyrocketed in developing countries world-wide and significantly increased energy demands. Thermochromic materials have been seriously considered for building and roofing materials because of their ability to change solar reflectance with temperature. Ideally, the color of the roofing material containing the thermochromic pigments would turn dark in low temperatures and white at higher temperatures to absorb solar heat in the winter and reflect solar radiation in the summer. In Phase I, Sommer Materials Research, Inc. investigated an inorganic thermochromic coating for prime roofing granules. The ceramic-like coating would be weather resistant, biocidal, UV-resistant and can be a low-cost replacement for clay-like color coatings currently used on the roofing granules. The thermochromic material could also be used as thermochromic paint for existing low-slope roofs. Effective methods to quantify the amount of UV damage on the thermochromic materials at high and low temperatures were devised. Various cement compositions, liquid chemistries and mixing procedures were investigated and tested to produce a compatible matrix for the thermochromic pigment. The thermochromic cements were found to be very sensitive to pH, temperature, chemicals and processing conditions. The thermochromic cements degraded under UV exposure- even though the compositional makeup of the cement should have protected the pigment by absorbing harmful UV radiation. Constraints needed to keep the thermochromic dye from degrading during ceramic processing on a larger commercial scale were also difficult to implement. Alternative options were investigated to make a viable thermochromic roofing material. One approach produced materials with improved UV resistance and commercial process ability- a technology meriting future research.
