ventilation

In recent years, earth-to-air heat exchanger (EAHE) systems, which is a method of pre-cooling and pre-heating outdoor air with earth-to-air heat, have been attracting attention as one of the technologies to achieve ZEB. However, at the operational phase, in order to achieve both energy saving and suppression of dew condensation control, EAHE control methods such as the timing or amount of outdoor air introduction have not been established.

The accurate estimation of the local wind pressure coefficient is crucial in the numerical modeling of natural or mixed ventilation in buildings subjected to wind. Building ventilation modeling typically relies on average wind pressure coefficient values specific to the building façade and wind direction. While the literature provides some correlations and standards for building wall-average pressure coefficients, these values are only useful in the absence of additional information or a database, as they can vary significantly based on urban forms.

Elderly people residing in nursing homes spend a vast majority of their times indoors and often in common recreation areas, to allow for socialization and interaction. Elderly people are a vulnerable age group. Hence, it is essential to provide them with good breathable air quality during these common activities and reduce cross contamination through ventilation. Prolonged exposures of elderly to contaminants may adversely affect their health, quality of life and increase medical expenditures due to frequent hospitalizations.

One proposed mitigation to reduce transmission of the SARS-CoV-2 virus and other airborne pathogens is to increase ventilation in buildings. This measure can be difficult to implement in existing buildings and has the potential environmental costs of increased energy consumption to condition the additional airflow, as well as other potential costs such as the disposal of existing serviceable mechanical equipment and the manufacture and delivery of new equipment.

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.