Simulation and evaluation of sheltering efficiency of houses equipped with ventilation systems

When an air pollution or extreme weather event occurs, outdoor particles entering a house may affect the indoor air quality and endanger human health. We began researching the sheltering efficiency of houses by determining the penetration factor. This involved using a test chamber to simulate the process of outdoor particles passing through cracks of a household sliding window and elucidating the most effective sheltering configuration of houses in air pollution emergencies. The results illustrate that a high air exchange rate corresponds to a high penetration factor, and the concentration difference between outdoor and indoor affects ventilation efficiency. For universal household sliding windows, frames made of plastic coupled with an air exchange rate less than or equal to 1.20 h−1 can prevent particle penetration more effectively in air pollution emergencies. As the external particles gradually disperse and the concentration decreases, a ventilation system with a large air exchange rate may effectively purify the indoor air. However, UFPs of less than 69 nm are able to undergo penetrate in a large amount, especially when the air exchange rate is lower than 1.20 h−1. Therefore, effective housing sheltering is still a challenge if the external source is primarily UFPs. In addition, laboratory simulations may overestimate/underestimate the penetration factor and the ventilation efficiency if the particles with a one charging state are the only source.