Skip to main content

Natural Ventilation

 As the weather is getting warmer, it is a good time to look into how to make our spaces cooler and more comfortable for summer. For centuries, people in Africa, the Middle East and other hot climates have developed ingenious ways of ventilating their spaces and cooling the air that flows through their buildings. Traditional ways of building in these hot climates include building rooms around a courtyard, often with a water feature and vegetation in the courtyard to cool and refresh the air. Their streets were traditionally very narrow, so that one building would shade its neighbour, preventing heat buildup. Their buildings were crafted from clay with very thick walls and roofs to  keep the rooms cool, and they often included wind catchers that act like chimneys to draw the air through their buildings.

Windcatchers on the rooftops in Iran
Creative commons licensed from https://es.wikipedia.org/wiki/Captador_de_viento

But how can we capitalise on these traditional ideas in our own homes, so that we don't need energy guzzling fans and airconditioning? The first thing to understand when looking at natural or passive ventilation is how the air flows in a room. If you have the window directly in line with the door, it tends to create a tunnel of air, leaving most of the room unventilated, resulting in a hot and stuffy space for most of the room. If you have a choice of windows to open, use one diagonally opposite the door - this will also reduce the funnelling of the air that can be quite draughty. Now the air can flow into all the corners of the room, as you can see in my diagram here.

Air flow depends on the position of openings

If you have a room where the window is directly opposite the door, you can adapt it slightly by hanging the door with the hinges on the other side, so if the door is half open, the fresh air will be channelled to the opposite corner. It is best to call in a carpenter to do this, as it can be quite tricky to re-hang a door so that it opens and closes smoothly.

We can also capitalise on the principle that hot air rises - the cool air will enter the room at a low level, and as it heats up, it will tend to rise. This is why you find many homes have fanlights, so the warmer air can escape. In summer, it is good to keep all the fanlights (to windows and above the doors) open day and night to keep the rooms well ventilated.

Cool air comes into a room at a low level and rises as it heats up

Another way to help cool a room is with the addition of pot plants - the air is cooled through evapotranspiration, as well as evaporation from the soil and drip tray. A favourite is succulents, which are also excellent at removing carbon dioxide from the air and replacing it with fresh oxygen. They are also very resilient to drought, so if you go away for a few days or simply forget to water them, they survive very well. 
My little family of succulents

Another method that uses evaporation is to have water in a porous (unglazed) ceramic pot close to an opening. The water is drawn to the outside of the pot where it evaporates, and lowers the temperature of the room. This is a method in common use in North Africa and the Middle East, and there is evidence of its use around 800CE in the palaces on the east coast of Africa. You can use a ceramic wine cooler to get the same effect - place it near a window so that the sun can heat it up for maximum effect.

An unglazed ceramic wine cooler



 

Comments

Post a Comment

Popular posts from this blog

Welcome to my blog

Sitting outside the Wits Architecture Building My name is Anne. I have just retired from the University of the Witwatersrand in Johannesburg, South Africa where I was an Associate Professor in the School of Civil and Environmental Engineering, working in the environmental engineering and project management domain. Prior to that, I was a lecturer in the School of Architecture and Planning, teaching many aspects of architecture, including architectural history, design and skills in graphics. Before lecturing at the University, I worked briefly in local government as a junior architect and then in a commercial firm of architects. After this I ran a private architectural practice with a focus on architectural heritage design. I have qualifications in architecture, construction management and employment creation through construction. Now that I have retired, I want to continue to provide educational context about architecture, engineering, design and project management in a different forum ...
Post a Comment
Read more

Rain gardens

  Last year I wrote a blog on green roofs , so today I want to follow up with a much smaller and more versatile type of green infrastructure, the rain garden, sometimes called a bio-retention cell. These can be introduced into a small corner of your garden and have even been used as slightly modified planters along roadways where there is not enough space for a more extensive vegetated installation such as a swale. A vegetated swale Creative Commons Licensed:  https://commons.wikimedia.org/wiki/File:Planted_brick_swale,_balfour_street_pocket_park.JPG One of the most severe environmental impacts of urbanisation is that the porous soil and vegetation of the natural landscape is replaced by impermeable materials for buildings and roadways. This prevents rainwater from seeping into the soil and replenishing the groundwater (the water naturally stored underground) and becoming cleaned by percolating through the plants and soil before returning to the natural water courses. In urban...
Post a Comment
Read more

Useful and beautiful

  Have nothing in your houses that you do not know to be useful or believe to be beautiful. (William Morris) Morris was born in 1834 and lived through one of the most profound changes in design and manufacture of everyday objects, brought about through the industrial revolution. His rejection of the over-elaborate designs of this first generation of industrial design is seen in his passion for hand-crafted work, something of a luxury in his own day, but even more so now. The question is whether we can still uphold his philosophy, but capitalising on the wide array of industrially produced goods that are now available. Wallpaper design by William Morris We live in an era of overwhelming choice, ranging from the most tawdry or over-elaborate to extremely beautiful pieces, the latter often very reasonably priced. I find my own taste will be met either by the cheapest or the most expensive item on offer, perhaps an indication of my Modern Movement upbringing! So what should we be looki...
Post a Comment
Read more