In Green Buildings emphasis is given to utilize renewable energy sources and natural ventilation rather than mechanical ventilation. I came across a plan a few days back which had windows and doors but didn’t follow the principal of cross ventilation. There are instances where making minimum of 2 openings on adjacent/opposite walls which are open to the outdoor environment is not possible, but if the builder is planning to make the building Green and get it certified by any of the authorities like IGBC, LEED, GRIHA etc., special attention should be given by the team to provide openings to facilitate cross ventilation in the design stage itself.
In one of the rating systems Cross Ventilation and Natural Ventilation can get you a 2-4 points.Cross Ventilation also leads to decrease in use of Air Conditioners thus reducing electricity consumption and ultimately reducing Green House Gases emissions.
What is cross ventilation?
This form of ventilation drives air from openings at one side of a building through to the other. It’s success depends on the tightness of the building envelope – the physical separator between the interior and the exterior environments of a structure.
The direction and amount of wind available, the potential passage of air through vents, chimneys and other openers and how well wind is able to travel through a building also affects ventilation.
When constructing a building, it’s important to know which way the wind is likely to blow if you want to make the most of cross ventilation. The position and size of vents, windows and doors also has a bearing on the effectiveness of this form of ventilation.
Why use it?
This natural form of ventilation is effectively free and will ensure a building is properly cooled. There are no mechanics or electronics to be maintained and it is possible to prevent excess moisture and heat building up in ceiling cavities.
Wind ventilation also delivers on all three drivers of ventilation: maintaining minimum air quality, removing heat and other pollutants and facilitating air movement to enhance thermal comfort.
Wind ventilation is the easiest, most common, and often least expensive form of passive cooling and ventilation. Successful wind ventilation is determined by having high thermal comfort and adequate fresh air for the ventilated spaces, while having little or no energy use for active HVAC cooling and ventilation.