Cross ventilation is a natural method of cooling buildings that utilize the wind to move fresh air through the structure. Designing buildings with good cross ventilation can significantly reduce the need for mechanical cooling systems, resulting in energy savings and improved indoor air quality.
One of the easiest ways to make your project more efficient in terms of energy usage is by enabling cross ventilation. Of course this is already a well-known topic, but placing openings in opposite directions is not the only way we can achieve the effects of cross ventilation.
Why Cross Ventilation Is Needed?
1. Comfortable Conditions
Cross ventilation is a natural and effective way to cool buildings, and good design strategies can significantly improve the flow of air through the structure. This improves indoor comfort by making it cooler.
2. Reduction In Energy Usage
By utilizing the prevailing wind direction, strategically placing openings in the building envelope and using elements like courtyards, green roofs and walls, architects and builders can design buildings that are energy efficient, comfortable and healthy.
3. Reduces Electricity Bills
Reducing the amount of energy used, consequently reduces the money spent on electricity.
4. Reduces The Effect Of Sick Building Syndrome
Sick building syndrome is the reduction in productivity and interest that occurs in the occupants of a building. One of the reasons for this is absence of fresh air due to its stagnation, resulting in higher levels of carbon dioxide. This can happen in fully air conditioned spaces like offices and classrooms.
- Bringing in fresh air reduces the effects of sick building syndrome.
- It circulates air without compromising on occupant comfort.
Strategies To Improve Cross-Ventilation
There are several design strategies that can be used to improve cross-ventilation in buildings. Some of them are:
- Building Orientation
- Providing Narrow and Longer Corridors
- Having Open Plans
- Provision of Openings
- Placement of Openings
- Operable Opening Systems
- Green Roofs and Walls
- Roofing Systems
- Creating Stack Effect in Buildings
- Reducing Heat Gain
1. Building Orientation
The orientation of a building has a great impact on the amount of windflow it receives.
- One of the most effective ways is to orient the building so that the longest facade is perpendicular to the prevailing wind direction.
- This will ensure that the wind can enter through one side of the building and exit through the other, creating a natural flow of air through the structure.
2. Providing Narrow And Longer Corridors
Providing longer corridors helps wind to travel through buildings easily.
- Orient the corridors to the wind direction for better results.
3. Having Open Plans
It is common sense that winds move more efficiently when there are less obstructions.
- Have open interiors
- Have more openings on facades like windows, jaalis, louvers etc.
- Have open corridors and green spaces like balconies and courtyards inside the building.
4. Provision Of Openings
Another important design consideration is the use of openings in the building envelope.
- The openings, such as windows and doors, should be strategically placed to allow for the flow of air through the building. For example, placing windows on opposite walls of a room can create a cross breeze that will help to cool the space.
5. Placement Of Openings
The placement of openings is another important factor.
- Adjacent- Doors and windows can be placed in the adjacent walls. This method is beneficial if the most used area in the room like couches and beds are placed in between them.
- Opposite- Placing fenestrations on the opposite sides of a room is the most efficient method to provide cross ventilation. This helps flowing winds to cover the entire room, cooling it well. However, it is practically not possible for all rooms in a building to have this due to site constraints.
- Upper Openings- Openings on the roof can help wind to flow inside by angling it well.
6. Operable Opening Systems
Operable window systems, louvers, jaalis, skylights etc. can be used to allow for natural ventilation when the weather is favorable.
- Louvers And Jaalis- These elements allow winds to move faster and longer into the interiors due to the patterns on their surface.
- Operable Windows- These windows can be opened/closed and oriented towards the prevailing winds direction upto a certain extent.
7. Green Roofs And Walls
The use of green roofs and walls can also improve cross-ventilation in buildings.
- These elements can act as natural air filters, removing pollutants and reducing the temperature of the air entering the building.
- Green roofs can also reduce the heat island effect in urban areas, helping to cool the surrounding environment.
8. Roofing Systems
Windflow can also be enhanced by roof designs.
- Stack Roofs- These roofs are angled, which forces wind to flow down to the interiors.
9. Creating Stack Effect In Buildings
- Other design strategies that can improve cross ventilation include the use of courtyards, atria and light wells.
- These elements can create a stack effect, drawing hot air out of the building and replacing it with cool fresh air.
10. Reducing Heat Gain
While encouraging cross ventilation, it is equally important to reduce the amount of heat seeping into interiors.
- The use of shading devices such as louvers and overhangs can help to block the sun's rays, reducing the need for mechanical cooling.
Use of cross ventilation is probably your first go-to when trying to make your designs more sustainable. But it is important to make sure the air which flows inside is removed of pollution and heat as this might achieve the opposite of what you intended for your users.