A practical feedback on the ventilation of portable site sheds

Site sheds are widely used on construction sites as portable workplaces. They are generally ventilated naturally by opening windows and doors. However, when the weather is cold, rainy or windy, which can be frequent in some regions, workers keep the openings closed in order to maintain an acceptable thermal comfort. The resulting insufficient air change rate was highlighted in a previous work [1]. Beyond a poor IAQ, the lack of fresh air supply also leads to a significant increase in transmission risks of diseases through aerosols, given the high occupancy rates (about one person for two square meters) in such closed environments. When site sheds are used as portable lunchrooms, occupants cannot wear a mask during lunchtime to reduce biological emissions. In this framework, a mechanical ventilation system was designed as a collective protection equipment, dealing with many technical constraints: avoiding air mixing, bringing fresh air to each occupant, being compatible with portable equipment and with occupant thermal comfort, not degrading the use of current equipment (lighting, sink, refrigerator, etc.). The designed system is assessed in this paper.