Simulations programs on hourly basis for energy consumption and indoor climate have traditionally been based on a relative simple model for the operative temperature independently of the location of the person in the room. In practice the location of the person has a significant influence in buildings with greater glass surfaces. A person behind a window directly exposed to the direct sun light will have a completely different operative temperature than a person behind in the room in the shadow or in an area with shading devices. Designing rooms with big glass areas therefore has a great effect of the thermal comfort in the rooms. When calculating the consequences for the thermal indoor climate, the surface temperature is an important factor. To find a simple measure for the heat loss from a person, the operative temperature can be used. The mean radiant temperature plays an important part in calculating the operative temperature and here the angular factor is used. The air temperature and the temperature on the surfaces can easily be calculated. When one wants to find the angular factor between two surfaces, one can find a specific equation for the angular factor to be used in the calculations. However, the real problem is calculating the mean value of angular factor between a seated/standing person and a vertical/horizontal rectangle since there are no direct formula for calculation of the angular factor between the surface and a person. This paper deals with a method for solving this problem by going through a complicated iteration process for all cases and setting up a solution matrix to be used in computer analysis programmes.