Naturally Cool
Staying cool naturally is easier, cheaper and better for the environment than you may think.
Wednesday, April 2, 2008
Samui has evolved rapidly into an internationally renowned destination. During that growth the environment has undergone many changes. Awareness is now being raised about potential damage to the beauty that has made the island so popular.
Positive action is being taken to protect and preserve the island whilst allowing it to continue developing. But, as individuals working, living or staying on Samui, we have a responsibility to assist with maintaining that natural tropical environment.
There are numerous things we can do to improve the situation. Such as using passive cooling techniques which helps the environment and saves you money.
Employing natural or passive cooling techniques cuts the amount of electricity needed and therefore saves on air-conditioning costs for you as a home owner. But it also reduces the amount of harmful emissions which contribute to global warming and acid rain.
Passive cooling can be applied easily to any home and there are three main methods: blocking the heat; removing internal heat; and reducing internal heat sources. Each of these methods has a number of free or low-cost solutions that can be easily utilised. The best results will be achieved by employing all three methods. But any changes you make that reduce the use of your air-conditioning will help both you and the environment.
Blocking the heat from your home can be achieved in many ways. Most effective are insulation, reflection and shading. Insulation may be more associated with keeping homes warm in cold temperatures, but in contrast it also helps keep your home cool in hot climates. Heat is absorbed through roofs, so by insulating the attic floor it will prevent that heat from radiating down into the house. This can be done easily and cheaply in most circumstances. The concept of fitting double glazed windows works in the same way but is obviously more expensive to install.
The cooling method of reflection is also easily achieved. House colour is one of the most important considerations in passive cooling. Dark coloured exteriors absorb 70% to 90% of the sun’s radiant energy that hits the surfaces and some of this absorbed energy is transferred into your home resulting in heat gain. Light-coloured surfaces effectively reflect most of the heat away from your home. Placing a foil barrier beneath your roof tiles; having tinted-glass fitted or applying a reflective coating to the existing windows are other ways of blocking the heat from entering the house.
Drapes and curtains made of light-coloured fabrics reflect much of the sun’s rays and help reduce heat gain. The tighter the curtain is to the wall, the better it will reduce heat gain and two-layered drapes are most effective for cooling. Blinds aren’t as effective as curtains but can be adjusted to let in some light whilst reflecting the majority of the sun’s heat. The more reflective side of the blinds should always face outward.
Special heat and light reflective materials are available. However, even without such fabrics, benefits can be felt simply by closing curtains during the day; specifically on any window that gets direct sunlight. Exterior shade screens such as bamboo blinds can also prevent sun from entering a window.
Shading is the simplest and most effective way to cool your home and reduce your energy consumption. In fact, up to 40% of the costs of cooling can be saved by simple shading techniques. Landscaping and the use of curtains and blinds can have a considerable impact on the use and costs of running air-conditioning.
When landscaping the area around the house, trees, vines and shrubs can be used to shade your home and reduce your energy bills. To be most effective, trees should be strategically located in relation to the sun’s path over the house. You can ask a local nursery to recommend varieties which are fast growing and tall enough to be effective. To keep themselves cool, trees take water from the ground into their leaves. As this water evaporates from the surface of the leaves, it cools the tree. This evaporative cooling also cools the surrounding area.
Vines tend to grow very quickly and provide effective shading and cooling. Grow them on trellises placed on the hottest side of the house, with a gap behind them to trap cool air.
Shrubs can protect the lower parts of walls from heat gain by blocking the sunlight and light reflected from stone patios. But take care when planting any trees or large bushes to ensure that the roots will be clear of underground pipes, septic-tanks, and the house foundations.
The removing of interior heat usually requires some form of ventilation and this tends to involve a little more effort and some minor alterations to your home. But it can still be done relatively cheaply and easily. One very simple way is to open strategic windows and create a thermal chimney. In basic terms this can be achieved by opening the lowest windows on the side from where the breeze is coming. Leave the interior doors open, and open the upstairs windows on the opposite side of the house. The warm air in your house will naturally draw upwards and out of the higher windows. Fitting roof vents and ridge vents will both provide effective attic ventilation.
Ceiling fans are very efficient and use less than one tenth of the wattage of an air-conditioning unit. They can also work well alongside the unit. By running both together, the temperature setting can be set 9 degrees higher and still result in the same room temperature, whilst saving 30% of air-conditioning costs and energy consumption. And by using a programmable thermostat and timer for your air-con unit you can limit unnecessary use when you’re asleep or out.
The final passive cooling technique is to reduce heat sources within the home. For example, turn off incandescent light-bulbs as only 5% of the energy is light, the other 95% is heat; placing lamps or TVs near to the thermostat will cause the unit to run longer; when cooking remember that microwave cookers generate almost no heat and barbeques keep all the heat outside.
Cover pots when cooking indoors, air-dry clothes, fit exhaust fans in the kitchen and bathroom and insulate your hot-water heater. All of these things will help.
If you’re having a new home built then you can incorporate passive cooling techniques right from the start. The Aqualina project in Maenam is a fine architectural example of how to utilise passive cooling features. Overhangs and planted roofs help to keep interior temperatures down and the clever use of a water irrigation system on the roof offers further cooling benefits created by the evaporation of the water.
As individuals we may not be able to save the planet, or even Samui. But there are things we can change about the way we live which could impact on environmental issues that affect us all. Employing some form of passive cooling technique is easy, logical, responsible and economically beneficial for everyone.
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