Old and New Ways to Cool Buildings and Cities without Aircon

 

This very old church in the Atacama Desert has many of the cooling features which we'll be talking about - thick walls, white paint, no windows on the sunny side, recessed doorways and small openings in the upper levels which draw in fresh air 

 

Air conditioning won't save us if temperatures continue to rise. Here's why and what we can do instead. 

 What’s wrong with Air conditioning?

1.       Air conditioning already accounts for between 10 and 14% of global electricity consumption and 4% of global emissions (more than flying) and demand is expected to triple by by 2050 as the planet warms, populations increase and more people move into cities. Cities are significantly warmer than the surrounding countryside because of all that concrete and glass, plus the heat from traffic and human activity.

2.       Air conditioning adds to global warming in three ways. If made and operated with non -renewable energy they add to the greenhouse gases which exacerbate climate change. They use and release greenhouse gases directly into the atmosphere and they pump waste heat outside the house or shop to the detriment of all. They aren’t even very efficient at what they do, wasting 30% of the energy they consume and we have already been warned that high demand during summer is likely to cause blackouts as has already happened in parts of the USA.

3.       Cooling individual homes is also costly and often out of reach for individuals and communities most in need. It’s cheaper and more efficient to cool whole areas at once and everyone benefits – the householder, the immediate neighbourhood and the rest of the world. While some of the more elaborate systems may be beyond the capacity of many communities, there are also affordable more affordable options which can be implemented by almost anyone. As you'll see from the following, the categories below aren't mutually exclusive, but often work in combination with other elements.

Six Easy Ways to Cool Cities without adding to the Problem 

Learning from History

Traditional architecture and urban design in hot countries can teach us a lot about how to manage in future. See for example the windcatchers of Iran, the thick earthen walls of older buildings in the Middle East, the  white or light coloured buildings around the Mediterranean and so on. For more on this see DWs excellent video  or the article in The Conversation. Other warm countries including Australia also have some novel solutions which could be adapted for use elsewhere. I will include some of these as we go. 

Nature -based Cooling Solutions

 Siting and Orientation

Much more could be done with respect to orientation. Japan’s Feng Shui masters understood this far better than many of our town planners today. Although their aim was to maximise the flow of Qui or life force through a building to prevent the buildup of stale pockets of air, we can employ the same principles to maximise cooling by being aware of prevailing winds and ensuring good airflow through buildings and streets.

Catching the Wind 

In Trinidad, Cuba, shutters, louvres and grilles replace conventional windows. A small opening allows for cross ventilation and the narrow street brings in cool air from the sea

 

 

A similar opening at the back of the house creates throughflow and looks out onto a leafy courtyard

In the more affluent parts of Havana, breezy porticoes and colonades make both the outdoors and the interiors cooler

Cool tiled surfaces, water features, plants, high ceilings and wooden shutters keep internal courtyards at a pleasant temperature

In tropical Queensland and Darwin, houses were elevated and usually had verandahs all around to catch any passing breezes. The higher elevation also gives some protection from flooding which is important in countries which experience monsoons. 

[On the subject of extreme weather, another feature of all Darwin houses since Cyclone Tracy flattened the town in 1974, is a cyclone -proof room, deep in the heart of the building. Don't hold your breath though. In New South Wales, developers overturned legislation which was to make white roofs mandatory].

 

A lovely example of a pre - aircon era  'Queenslander' - the house is elevated and has lots of verandahs to catch the slightest breath of air

This Photo by Unknown Author is licensed under CC BY-NC-ND

Interior Cooling

Another idea which has fallen out of favour since the invention of the electric fan, is the Indian Punka – This involves wide strips of fabric or bamboo suspended from the ceiling and being moved back and forth manually or mechanically to increase airflow within a room. In humid climates, moving air increases the evaporation of perspiration from the body and thus enables it to cool itself better. While any kind of fan will do this to some extent, these cover much larger areas. There used to be a big sprawling hotel in Darwin which had rows of electrically driven Punkas in its Green Room which was also full of palms and plants. I don’t know if they or the hotel still exist, but I’m sure it would take very little energy to run them, especially if solar powered.

Sun -smart Building

Knowing how the sun tracks across the sky during the day and through the seasons is important for the positioning of  windows, awnings, verandahs and entryways, so that they offer maximum protection during the heat of the day but admit light in winter and when the sun is low in the sky. Shading with awnings, shutters or vegetation is also necessary, as is good insulation. 

Many of these features are also beneficial in places which have both hot summers and cold winters. There is new tourism development near Hobart which when fully operational, will be entirely emission - free and won't need heating in the winter either. 

 

At Iron Creek Bay, narrow, angled and double-glazed windows admit the morning sun and capture the views over the sea at this development but keep out the harsh summer sun. Additional ventilation and light is provided by skylights and rooftop ventilation

Architect Misho, of Misho and Associates explains how the accommodation units are made with triple -layered laminated timber, which help to maintain an even temperature in summer or winter

 A variety of foils and window treatments have also been developed which reflect heat back into space. While these are especially useful for skyscrapers with their acres of glass, they can also be used to reduce temperatures in places such as data centres and even very small applications such as market stalls.

 

The front wall of The Pod -a very tiny house also in the Hobart region, has a front wall made entirely of double glazed glass but it faces away from the noonday sun and is tinted to cut out excessive sunlight  while still retaining the view

 

The small scale of this house also means that it requires very little energy to heat or cool it. Appliances such as the stove which could heat the building are at the rear of the house where there are either no windows or only very small ones

Because of the huge amount of energy needed to cool glass -fronted buildings, leading architects, engineers and even the Mayor of New York want to ban the use of glass in offices and high rises altogether. This could be one way of reducing energy demand without having to do major retrofitting. 

Vegetation

I have often written about the benefits of vegetation in the city, see for example Greener Buildings, Greener Cities, so I won't repeat it all here. Suffice to say,  three years after planting its award -winning green corridors, the City of Medellin in Ecuador noted that temperatures within them were 2°C (3.6°F) lower than elsewhere in the city and many other cities have since followed suit. Singapore with its Sky Gardens, street plantings and reflecting pools is a perfect example. Note also what the narrator says about the effect on people's wellbeing and the need to keep fossil fuel burning cars and power plants out of the city to reduce heat gain.

 

Trees are better but...

The much maligned square of lawn which used be in front of or around the back of every Australian home, has since been replaced by less labour and water intensive materials such as paving blocks, but it also helped to keep homes cool by acting as a heat sink. By absorbing water and rainfall and releasing it in hot weather, they cooled in much the same way that pools or wetlands do.

Water

Simply the sight of water features such as  pools and fountains make us feel cooler, but they also cool the air which flows around or over them. This is the principle of evaporative cooling and underlies the Japanese tradition of watering pavements.

One Australian innovation which used this idea before the days of refrigeration was the Coolgardie Safe. This involved placing wet hessian over a box made from perforated metal or a wooden frame with mesh sides, and hanging it in the shade. This not only kept meat and other perishables fresh, but stopped flies and other pests getting in. Perhaps this idea could be adapted to street stalls, home use or even larger areas. The models shown in Wiki and elsewhere are far more complicated than those which were in general use in homes, even as late as the 1950s.

On a much larger scale, the Madrid fish market, the second largest in the world, used evaporative cooling and reflective paint to reduce its energy bills by 70%. Just the paint alone reduced the interior temperature by 6-7°C (11°F}.  

Water cooled by colder night air and pumped by solar energy during the day, is also used to cool a demonstration building in Seville, one of Europe's hottest cities.

 

The Global Centre of Adaptation in Rotterdam makes use of water to cool itself in several ways. Built on the water and surrounded by it, water is also piped through its concrete support pillars.

 

District Cooling

Singapore is a leader here too, using a centralised underground system of water pipes to cool whole city blocks and districts. Gujarat in India, is building a whole new precinct to incorporate this principle, while Paris avoids this expense by running water pipes for district cooling through its existing sewerage system.

Using the Earth

Thermal Mass 

Slow to heat and slow to cool, the thermal properties of the earth itself could also be utilised more. In the hottest, driest parts of Australia for example, opal miners still build their homes underground. This not only provides excellent protection from the high temperatures but means building material doesn't need to be trucked in over long distances. 

 

This Hostel in the Atacama desert has thick adobe walls and is built low to the ground where the earth stays cooler. However, being in the Andes means that the desert also gets terribly cold at night. During the day the clay slowly absorbs heat, which is then slowly released at night

This home built by African Slaves in one of the humid parts of Cuba uses earth, light colours, high small shutters and thick overhanging thatch to keep cool

 

Passive Cooling 

The temperature below the ground generally remains constant and is often as much as 6°C cooler than the surrounding air. Simply drawing air underground and ducting it to various parts of a building can mean big savings on electricity consumption and the need for air conditioners. Hong Kong or Singapore - alas, I don't recall which, is now applying this principle to skyscrapers. As far as domestic applications go, this technology is sill in its infancy with all sorts of experimentation going on including DIY ones, in much the same way as solar panels were in the 1980s. However, because it doesn't require a great deal of fancy material such as rare earths and little ongoing cost, it seems to me to be one to watch.

While passive solar houses have been around for a while, a new house in Australia’s Blue Mountains (NSW) has been partially built underground. It relies on good insulation and mechanical ventilation to keep it cool and uses less energy than it takes to make a cup of coffee. It doesn't need additional heating to keep it warm in winter either. An additional benefit is that it is also fireproof, another thing which should o receive far more consideration in future. 

As you can see there is no one -size -fits -all solution to the problem of keeping cool in a warmer world. Much depends on local conditions, available materials and available funds. Most likely the answer will involve some combination of these elements. The UN has a handbook to help cities to develop their own plans according to their circumstances.