ventilation

The predicted and measured carbon dioxide (CO2) emitted by human respiration into an occupied space has been used as an indicator for controlling buildings' ventilation rates. However, this application assumes a constant emission rate for the entire population. Conversely, new knowledge has shown that this variable depends on the number of people in the room and their sex, diet, height, and above all, body mass and metabolic rate.

Urban settings and climate change both impact energy use, thermal comfort and ventilation of buildings. This is more noticeable in hot urban areas where the urban heat island effect is more pronounced; also, in densely built urban areas where thermal comfort in naturally ventilated buildings is affected by changes in natural ventilation rates because of surrounding obstructions. In some cases, overshadowing might alleviate the impact.

Gas-phase air cleaners can be used to either reduce occupant dissatisfaction for the same outdoor air flow rate or to reduce the outdoor air flow rate for the same resulting occupant satisfaction based on its clean air delivery rate (CADR). The latter lowers the required ventilation rate for the same indoor air quality and can thus lead to a reduction in energy use for preheating/cooling and from transporting the outside air. However, there is no current method or metric for determining the energy benefit of installing a portable air cleaner.

The ASHRAE Standard Project Committee on Ventilation and Acceptable Indoor Air Quality in Residential Buildings (62.2) has proposed an addendum to the standard that adds a harm-based Indoor Air Quality procedure as an alternative compliance method. The IAQ Procedure only considers 3 contaminants and only the sum of the harm from those three contaminants needs to be limited. This was determined by completing four stages of research.

The buildings ‘sector is facing multiple challenges due to the need to generalize a sober approach and to reduce its energy consumption, its CO2 emissions and its impact on climate change, to reduce its environmental impact and its carbon footprint, to reduce the burden of disease due to exposure to unhealthy indoor environments and to adapt and be resilient in the face of climate change and environmental changes such as the increase in pandemics, the urban heat island and outdoor pollution.