Using the utilization factor concept for natural ventilation

A well-known parameter in the calculation of solar gains for the heating requirements is the utilization factor concept. This parameter allows the assessment of the heating requirements diminishment due to the contribution of the solar gains, and it can be easily calculated as a function of the building inertia, and the ratio between solar gains to losses. The present paper analyses the utilization factor equation in order to obtain the relations among all the involved variables. Thus, using the transfer function method, a new and realistic utilization factor equation is obtained. A comparison between both expressions is made, and the differences encountered are explained. Taking account the usefulness of this concept for the calculation of the heating requirements, an effort has been made in order to use it for the calculation of the cooling requirements. In this case, we are interested in the calculation of the cooling requirements diminishment due to the contribution of the natural ventilation. Finally, the paper shows the dependency of the utilization factor as a function of variables like the daily distribution of the heating or cooling requirements, the daily distribution of the solar gains or the natural ventilation contribution, the number of hours of solar gains or natural ventilation, etc.