Can interior coatings of a space contribute to improve visual comfort and promote energy conservation? It is around this issue that the French company Saint-Gobain and the LIPID laboratory started a new collaboration. Saint-Gobain Research, leader in the field of materials for sustainable housing, wishes to develop materials that can better distribute natural light in buildings.
The laboratory LIPID has used its experience gained in the field of the evaluation and visualization of performance under Prof. Marilyne Andersen’s leadership to build a climate-based integrative approach in order to compare the impact of different ceiling tile choices when assessed in combination with façade properties. This approach has led to a better understanding of the interaction between facades and ceiling materials. Thomas Moisan, a recent graduate from Lyon's Ecole Centrale in Civil and Environmental Engineering, led this project within LIPID in the frame of his master’s thesis project. Amongst the more notable results of his work, he demonstrated that an increase in the ceiling’s reflection coefficient by 15% can bring every year up to 400 extra hours of comfortable conditions for vision (no glare, no under-illumination) when used in combination with a light-redirecting façade system (towards the ceiling), and up to 200 hours with a simple double-glazing. So many hours during which the use of artificial lighting might not be necessary. These results show that interior surfaces can play a significant role on visual comfort and energy consumption for lighting, and could pave the way to a new understanding of daylight harvesting as a subtle play between façade properties and interior surfaces.