The impact of size in fenestration designon the airflow and temperature in natural cross ventilation, case study:A two-bedroom Polish multifamily home

In countries with cold winters such as Poland, there is growing evidence for proliferating overheating in summer times due to climate change. Hence, buildings become more uncomfortable for their occupants during hot summers. To tackle this challenge, we use the passive strategies potential to adapt buildings in line with their experimental and engineering analysis of the indoor environment. This paper demonstrates the results of both thermal and airflow simulation of existing naturally ventilated in double-bedroom homes in Poland. Thermal and airflow simulation is used to improve the natural ventilation system and to address summer thermal comfort problems due to excessive hot airflow caused by climate change. In the first step of the research, over 300 multi-family home plans all over Poland were categorized by size, ventilation type, facade organization, and fenestration type. In the second part, computational fluid dynamics (CFD) analysis is used on 3D models to predict indoor airflow velocities for different levels of the building envelope airflow permeability. Then, a coupled thermal and airflow simulation with 2 different window size, fully open, and with 3 integrated shadings options (base model or no shadings, 30 cm overhang with side-fin, and 10 cm depth horizontal louvers) are done to investigate whether the more opened envelope reduces a summer overheating problem. The results for the optimized natural ventilation through fenestrations successfully address houses' summer discomfort problem by reducing the indoor temperature between 2–3C and in some cases up to 4C cooler than similar model with small windows.