The basic physics of sound propagation are simple, but the interaction of sound pressure waves with complex shapes and multi-layer constructions with openings, as you find in buildings, is more challenging. Controlling noise, both from the internal and external environment and from the internal mechanical and electrical services in buildings, is essential to create environments that promote aural communication and comfortable working conditions. Light is essential for function, but simply providing sufficient illumination by electric lighting is rarely adequate for high performance buildings. Lighting design must consider source intensities, distribution, glare, colour rendering and surface modelling if we are to create stimulating high quality interior environments. Daylight.