Thermochromic Materials as Passive Roof Technology: Their Impact on Building Energy Performance

Over the last few years, new materials have been developed which a priori, appear to improve passive energy efficiency in buildings. This article focuses on chromogenic devices that allow changing their optical properties in a reversible manner through some external stimulus. The covering of the envelopes may have different textures or colors, which determine the amount of solar radiation absorbed by the material compared to the incident radiation. In buildings with a high percentage of roof relative to facade, the surface finish plays an interesting role in the energy demand. In the present work, the influence of the application of thermochromic materials to the roofs of commercial buildings is analyzed. It has been demonstrated that the application of a thermochromic surface finish can produce savings of annual energy demand between 1% and 12% in kilowatt-hours and kilograms of CO2 and they become more significant for construction solutions with higher transmittances values. Then, the impact of applying a thermochromic finish per day is analyzed and which transition temperature range will be the most optimal to the highest energy performance is discussed. At the same time, an assessment is made of the optimal cost; although economic investment is not currently amortized, it is a good resource for reducing energy demand in buildings.