How to keep buildings cool without air conditioning – according to an expert in sustainable design

The hotter it gets, the more people turn on their air conditioners (AC). Indeed, air conditioning is rising in countries around the world: it is anticipated that by 2050, around two-thirds of the world’s households will have an air conditioner, and the demand for energy to cool buildings would triple.

However, unless the energy is generated from renewable sources, the increased demand would result in greater greenhouse gas emissions, which will contribute to global warming – and, of course, hotter summers. It’s a vicious cycle, but buildings may be designed to keep the heat out while also reducing climate change.

A lot of these strategies are about being in touch with nature and understanding how it works

Manit Rastogi

Air conditioning as we know it now, based on the refrigeration cycle, has been around for a little more than a century. Did humanity spend hundreds of thousands of years uncomfortable before modern air conditioning? No, they employed other techniques to stay cool, and these methods still function now. In some climes, a no-refrigeration strategy may suffice. In more demanding scenarios, the measures outlined below can minimize the size and cost of air conditioners or heat pumps, as well as the amount of energy they consume. Begin with the design stage to incorporate effective cooling into the home’s construction. Then, add active cooling strategies that utilize little or no energy or refrigeration.

High performance homes already include two basic features that reduce the need for cooling, such as high levels of insulation and very tight construction. This keeps the inside in and the outside out.

Windows and shading

Windows facing east and west are more difficult to shade. Blinds and curtains are ineffective because they block the view and daylight, and if they are placed inside the window, heat penetrates the structure. As a result, external shutters, such as those commonly seen on antique buildings in France and Italy, are ideal.

Nature’s approach of providing summer shade and winter sun is deciduous vegetation. Properly planted evergreen trees will avoid excessive late afternoon heating, which can occur even in winter, for some exposed western windows. The sun can be deflected by moveable outside screening before it enters the glass. You can use the shielding when it is needed and save it when you wish to take benefit of the sun’s heat.

Paint and glazes

Roofs are now commonly coated with special pigments designed to reflect solar energy — not just in the visible spectrum, but also in the infrared spectrum. When compared to ordinary paint, these can reduce surface temperatures by more than 10°C. High performance solar glazing on windows also helps, as do coatings that are “spectrally selective,” meaning they keep the sun’s heat outside while allowing daylight in.

There is also photochromic glazing, which changes transparency based on the intensity of the light (similar to some sunglasses), and thermochromic glazing, which darkens when it is hot, which can also be beneficial.

Building materials and make it massive

Buildings composed of stone, bricks, or concrete, or embedded in the ground, can feel cooler because of their large “thermal mass” – that is, their propensity to absorb and release heat slowly, so smoothing temperatures across time, making daytime cooler and nighttime warmer.

When the temperature rises, thermal mass absorbs heat and releases it when the temperature falls. This can be used for both heating and cooling. For thousands of years, high mass structures have been employed over the world to keep people comfortable by decreasing daily temperature changes. The theory applies to all homes, even those made of mass materials like concrete, gypcrete, masonry, earth blocks, and even water tanks.

Energy-Efficient Cooling

In hot, dry areas, evaporative cooling is utilized to cool and humidify. It improves on basic air flow by using fans to push a continuous stream of outside air through a wet pad into the living room without recirculating the air. These systems’ blowers consume far less electricity than a refrigerant-based air conditioner and even less than a heat pump.

While you’re more likely to find basic, low-cost window-mounted evaporative coolers, there are more sophisticated models that work alone or in conjunction with a ducted air delivery system to increase dispersion throughout the home.

All structures should begin with the basic structural cooling measures discussed earlier, such as effective insulation, air sealing, landscape shade, and, where applicable, thermal mass. These work in all buildings, anywhere. Applying one or more of the more active techniques can provide further cooling. Exterior shade that can be moved is always beneficial when direct sunlight hits the structure, especially on the east and west sides. Natural ventilation employing night flushing and cross ventilation is an useful next step in many regions.

Using fans to add a mechanical boost to natural air flow boosts cooling capacity, especially at night. Evaporative cooling is the next option, however it is only effective in certain regions. As a last option, energy-efficient heat pumps are always accessible.

Source: The Conversation || Zero Energy Project

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