Cross-ventilation, windows, and fans are all terms we frequently associate with when ventilation is discussed. When the thermal comfort in a room decreases, our mind automatically goes to switching on a fan or opening a window. 

However, has the thought come across that a space can be well-ventilated with minimal use of appliances, and other methods than windows?

Ventilation can be mechanized or natural, and sometimes even a combination of the two. However, the awareness to reduce the carbon footprint of buildings has created a wave amongst architects to design keeping sustainability in mind.

As sustainability becomes a need in architecture, let’s take a deep dive into sustainable ventilation techniques.

Natural Ventilation

Natural ventilation is a type of ventilation that does not require mechanics, is more cost-efficient, and is environmentally friendly. It utilizes passive methods of ventilating a space, that after analyzing the climatic factor of the site, relies on factors such as wind movement, temperature, and the immediate surroundings of the building.

Types of Natural Ventilation are:

1. Cross Ventilation
2. Single-sided Ventilation
3. Stack Ventilation
4. Night-Purge Ventilation

Natural ventilation must abide by LEED and NBC standards that dictate terms for providing the most efficient, and energy-efficient ventilation for a space.

1. Cross Ventilation

• In simple words, it refers to when wind enters a space through one opening, and exits through another, preferably on the opposite face.
• While doing so, it forces cooler air from the exterior and ventilates the entire space.
• As the wind exits, it forces the warm air in the interior to exit through the opening.
• Cross-ventilation is one of the best ways to circulate air and consistently maintain thermal comfort in a space.
• It is an adaptive feature in hot and humid zones. 
• It aids in reducing thermal pollution, reducing heat, and removing other pollutants.

2. Single-Sided Ventilation 

• There are one or more openings in one single external wall.
• It provides limited ventilation, even when there is little to no wind.
• The best way to maximize ventilation through this method is to have openings at the top and bottom.
• Through convection, warm air is expelled through the top opening, while cold air enters through the bottom opening.

3. Stack Ventilation

• Also known as the chimney effect or stack effect, it is a vertical natural ventilation system.
• It works on the principle of change in air pressure, temperature, and density levels.
• The two variables in play are height and temperature.
• Convection is the phenomenon that controls ventilation.
• Hot air rises upward to exit the building, to increase thermal comfort.

4. Night-Purge Ventilation

• Night-purge ventilation is a night-time method of ventilation.
• It is used in regions where daytime temperatures are extremely high and severely uncomfortable.
• Thus, the openings are closed during the day and opened during the night. This helps in flushing warm air out of a space and cool it for the next day.
• It is a way to remove heat from a building.

Mechanical Ventilation

With all this talk about sustainability, it doesn’t seem prudent to not talk about how we can maximise the use of mechanical ventilation without harming the environment. It is the truth that we cannot fully ventilate a place in our current age and time, without some mechanical help.

Let’s take a look at a few techniques for the same.

1. Opt for Energy-Efficient Appliances

• Ensure that the appliances that you use in a space have been rated for their energy efficiency according to the standards.

2. Optimum Positioning

• Place the ventilating appliances at strategic locations such that even when less in number, they still provide optimum ventilation.

Reichstag Dome, Germany

The dome of the German Parliament is an excellent example of how to maximise the use of natural ventilation, while seamlessly integrating the same into the architecture of the space.

• The dome uses the principle of convection and the Chimney effect, to ventilate the parliament effectively.
• The dome has a steel helical opening, that connects to the space below.
• Hot air rises and is forcefully pushed out through the dome’s top opening.
• The helical form causes the air to swirl and be pushed out faster, colling the space quickly.

Sick-building syndrome is a consequence of poor ventilation and lighting design. Thermal discomfort harms our health drastically, causing respiratory disorders, heart problems, and much more.

Natural, sustainable ventilation is important to avoid these complications, as it is easier for the human body to adapt naturally to the thermal comfort level of its choice, Mechanical ventilation such as air conditioners create sudden changes in thermal levels, affecting our health.

Of course, with environmental changes being a cause of concern, natural ventilation plays a small role in combating climate change, one space at a time.