I am always drawn to a deep shaded porch on a hot day, a place to escape the sun while enjoying the outdoor sights and sounds.
“Passive Cooling” describes a range of strategies an architect can use to create spaces that are cooler in the summer – without resorting to energy-intensive air conditioning. These strategies come from an understanding of the natural environment and how a building’s shape can influence it.
Traditional building elements like porches, arbours and cupolas – often reduced to mere decoration now – were originally key to providing relief on hot summer days.
Porches keep sunshine off the building’s walls and reduce the amount of sunlight reaching interior spaces through the windows and doors – known as “solar gain”. Since we know where the sun will be at any time on any date of the year, we can consider how much sunshine we want reaching inside.
Arbours similarly provide additional shade and may be augmented with flagstone or other cool-contact material – to create a space significantly cooler than sunny spaces immediately adjacent – known as a “micro-climate”.
Cupolas allow for warm air to escape a building at its highest point. This is when a building’s height can be used to take advantage of the change in air’s buoyancy as it heats, drawing in cooler air at the lowest levels which then warms and escapes the building at the highest levels. This is how a farm’s silos keep grain, and why ground floor doors of some tall buildings can be difficult to open – and is known as “stack effect”.
An understanding of the passive cooling principles of solar gain, micro-climate and stack effect can be used to create a building that is cooler and fresher in comparison to the conditions around it – without cranking up the A/C.