The Indoor Environment Group performs research that aims to maintain healthy and productive indoor environments while buildings are made more energy efficient. We study the links between indoor environmental quality, building ventilation, building energy efficiency and occupants' health, performance and comfort. We undertake experiments in laboratory and field settings and employ modeling to characterize indoor environmental conditions and evaluate the fate, transport and chemical transformations of indoor pollutants. We elucidate pathways of pollutant exposure, evaluate and develop energy efficient means of controlling indoor environmental quality, and provide input for related guidelines and standards.