This 440m2 extension consisted of 4 no. classrooms, a reception and an administration office. Using IES dynamic simulation software, the Architect's initial concept building was modelled to determine the window sizes and openings required to achieve compliance with the natural ventilation and daylighting requirements set out in CIBSE's TM52. TM52 is a guidance document for designing buildings to limit the risk of overheating, and ensure adequate daylight levels are present in work spaces.