Optimal window dimensions concerning daylight and heat in residential buildings of cold climate, case study: Ilam

One of the main elements in buildings that can considerably help to conserve energy is the external envelope, as it is the perimeter that should preserve interior spaces from the severe outdoor weather conditions. Overall, this envelope consists of three parts: transparent, translucent and opaque. Optimal design of exterior envelopes can significantly reduce heat gain, heat loss and energy consumption of buildings. In this research the optimal ratio of transparent part of the residential buildings to the exterior wall is studied. In this regard a parametric model to define the optimal dimensions of windows in residential buildings of cold climate (Ilam) to reduce energy consumption and benefit from daylight as the illumination source is introduced. At first, the base model for simulation is defined, rooted in previous researches about typology of residential buildings in the city. Then the weather data of the city, which was needed in simulation, was created and validated against the weather information of the city obtained from the meteorological station of Ilam. Simulation was carried out considering common building material and interior dimensions of typical residential buildings in the city, with the use of parametric software such as Rhino, Ladybug and Honeybee plugins, and resultantly the optimal window dimensions for southern and northern facades are introduced. The results show that the optimal window to wall ratio (WWR) for south window without any shading devices is 24% and with the shadings suggested by Building Code No.19 it is 19% . This value for the north window is 4%.