Buildings, as humans, need to breathe!
Like the lungs, buildings need to be able to breathe to make sure that fresh air comes in and dirty air goes out. There is the need to exchange the air from outside to inside and again from inside to outside. In this way, the building gets fresh air from the outdoors and then this air circulates through the entire building and then the indoor air goes outside.
Air exchange from outdoors to inside!
For most of the buildings, the air exchange from outside to inside happens in these ways:
1.unintentional via air leakages from windows, doors, and various holes such as joints and cracks in the building envelope.
2.intentional via natural ventilation, through opening windows/doors and air vents for deliberate venting by people and for people.
3.proper mechanical/hybrid ventilation, to add additional and controllable airflow in the buildings to provide a good indoor environment.
Why do buildings need to breathe?
We, people, need to breathe the air. That happens naturally outside where the fresh air is naturally found. However, people work and live in the buildings, some say we even spend 90% of our time indoors.
The fresh air gets in the buildings as described above, and the fresh air gets recirculated, used and polluted by various sources. Indoor air can build up high levels from people´s activity or building materials, etc.
1.by people´s activity (and also animals) – carbon dioxide (CO2), moisture or odours, etc.
2.by building´s materials/technology and equipment – furniture, floorings (VOCs as volatile organic compounds that are carbon-based compounds that easily evaporate)
3.by outside pollutants from traffic and Earth – CO or radon from the ground, etc.
Why it is necessary to ventilate?
The building needs to provide a suitable environment for people and their activity. And ventilation is one of the systems keeping the habitable environment – keeps the air fresh and healthy indoors.