Thermal and visual comfort assessment of natural ventilated office buildings in Europe and North America

Natural ventilation has the potential to significantly improve indoor comfort conditions and provide good indoor air quality by increasing both the indoor air velocity and the rate of air changes inside the building. However, the performance of this technique strongly depends on various parameters, such as climate, urban form and building characteristics (geometrical and thermal). With the aim of showing how natural ventilation can be successfully applied to existing office buildings in many different urban climates, an extensive parametric study has been carried out that takes into account the factors most likely to be relevant. Firstly, a characterization of different climates and the cities representative of them has been developed. Then, representative office buildings for each city have been modelled both in their base configurations and when natural ventilation is employed, in representative urban configurations. This task has been accomplished by coupling three different simulation tools in an integrated approach. CFD, thermal and daylighting simulations allowed exploration of which are the most relevant parameters that affect thermal comfort and have some implications on visual comfort as well. The large number of models simulated (almost 13 thousand) also provided the team with the opportunity to develop a new methodology for finding the best performing thermal models, based on Givoni's thermal comfort theory rather than monthly or annual energy needs.