Ventilative cooling effectiveness in office buildings: a parametrical simulation

Controlled Natural Ventilation (CNV) is one of the potential most effective passive cooling technique to reduce cooling needs of buildings in temperate-hot climate zones. However, a correct balance amid internal heat capacity, thermal insulation, and net opening area is important to achieve optimal results. The present paper shows results from an original simulation process carried out within the Course “ICT in building design” of the Master degree programme ICT4SS (ICT for smart societies) at the Politecnico di Torino. An office two-zone unit in Turin was simulated for fixed values of thermal insulation and internal heat capacity and increasing progressively external net opening area. Dynamic energy simulation was conducted for the cooling season period (May 1st ÷ September 30th) using Design Builder. The .idf output files were then used for the regression analysis, carried out by developing a Python script to allow for running the iterative process. A noise level related to a possible variation of the number of occupants was calculated through the Gaussian method. Results show that, while the internal heat capacity does not have a significant impact, thermal insulation could have a counterintuitive effect, i.e., the decrease of cooling energy with increasing opening area is less  for the configuration with low Uvalue than the for the one with high Uvalue , above 20% of net opening area.