When do we ventilate buildings?

We spend 100% of our time breathing air, so we need to have the best possible indoor air environment at all times. So we need to provide good indoor environment, via controlling air quality and reducing harmful pollutants indoors.


  • When we want to create a comfortable, healthy and safe environment for people – in homes, offices, schools, and other environments.
  • When we want to improve productivity of employees in office buildings and performance of students in schools.
  • When we want to reduce sick time, i.e. sick days at offices and absenteeism in schools.


  • When we want to enhance comfort for the buildings occupants, i.e. control temperature, humidity and other parameters of the indoor environment.
  • When we want to control occupants exposure to air contaminants, i.e. remove or dilute airborne contaminants.
  • When we want to ensure energy-efficient and sustainable operation of a building and also regulated costs, i.e. investment, operating and maintenance costs.

Special examples of when we need to ventilate

  • When the outdoor climate is more extreme, for example in cold climates or hot/humid climates.
  • When close proximity creates problems, i.e. to other outdoor conditions surrounding the buildings such as noise from traffic, location near polluting industries or seasonal issues with dust and pollen.
  • When we want to avoid heat build-up in more demanding time periods in a year, such as hot spells during summer. 
  • When the building envelope is too airtight and sealed: this is especially true for new built buildings and/or renovated buildings.
  • When we need to maintain specific conditions due to the purpose of a building, i.e. hospitals and laboratories.

Polluting sources in buildings

Fresh air comes into buildings where it then gets recirculated, used and polluted by various sources. Indoor air can build up high levels of pollutants from peoples activity or building materials. 

Our indoor air gets polluted by:

  1. People´s activity (and also animals) – carbon dioxide (CO2), moisture or odours, etc.
  2. Building´s materials/technology and equipment – furniture, floorings (VOCs as volatile organic compounds that are carbon-based compounds that easily evaporate)
  3. Outside pollutants from traffic and earth – CO or radon from the ground, etc.


Want to read more about the air?

Download our book, AIR. The aim of the book is to provide insights into the factors and circumstances, including the outdoor environment, that significantly influence the creation of a good indoor climate and energy-efficient ventilation solutions.

Download AIR by Swegon Air Academy
Duncan: This castle hath a pleasant seat; the air nimbly and sweetly recommends itself unto our gentle senses.
William Shakespeare, Macbeth