Keeping cool about air conditioning

SiteFeatures: Keeping cool about air conditioning

Keeping cool is turning into a passion this summer but what does it take to get a cool night’s sleep?

The British summer is unpredictable to say the least, but with the recent spells of warm weather it looks like this summer could be a scorcher. Weatherman, Bill Giles is predicting a warm July with the best of the sunshine early and late in the month so as the temperatures soar you’ll want to make sure you keep cool indoors.

Despite furious scientific debate over the cause of ‘global warming’ (This week sees a report from the Geological society of America claiming the effect of cosmic rays on our climate might outweigh that of the greenhouse gas carbon dioxide.), pretty well most of UK’s weather experts say it’s going to get warmer in future years.

Bill Giles has predicted that in 30 or 40 year’s time the South West of Britain will be as warm as the Spanish Costas are now. Hoteliers, engineers and planners in the West Country should be thinking about the future now, Giles comments, if we are not to let the area develop randomly with little control over water, traffic and environment. Despite Bill's extensive experience and high profile concerning global warming, no-one is planning for the big heat wave - yet.

In the UK most homes are not fitted with air conditioning units as standard although many offices and public buildings are. Overseas the situation is very different. Air conditioning has been a passion in the US for many years, indeed it’s almost impossible to imaging what life would be like in the southern states without air conditioning.

In Spain, most new homes on the Costas are now being built either with air conditioning fitted already or with the plumbing fitted ready for easy retro fitting.

But the majority of us Britons traditionally suffer in silence. Pushed to comment we'll probably say, “It’s only sweltering for a week or so a year isn’t it?” The tide is turning though and, as A/C in cars is becoming very common, more people looking to see what can be done in our homes too.

Fans
There are fans of all sorts and styles and these are a very cost-effective way of keeping cooler on sweltering nights. Fans can be bought for as little as £4.99 but go for a slightly better model if you want quiet operation. The slightest bit of out-of-balance in the blades will vibrate the unit horribly, making a racket by shaking the furniture it’s standing on. However much you thought the heat was keeping you awake without the fan, you won’t sleep with such a racket going on either!

A good price may be an incentive to impulse-buy but do think of where you will put the fan before you purchase it. A free-standing pedestal fan may be more suitable for many locations in the home and could even be a style item.

If you fancy the feeling of an exotic Caribbean beach house you could install a ceiling fan into your home. Ceiling fans have become extremely fashionable and are now available in a range of finishes to ensure they complement your décor.

Dehumidifiers
Dehumidifiers don’t cool the air very much, but will reduce the humidity and so it will feel a little cooler. However, if you don’t have the luxury of a tumble dryer you might consider one as a dual-purpose unit. A dehumidifier will take the moisture out of the air and can significantly reduce the time it takes for clothes to dry and can double up to help keep cooler on sticky nights.

Dehumidifiers work by passing air from the room over a series of cooled pipes just like the ones in your freezer. The moisture in the air condenses on the cold pipes and runs off into a tank that collects the water. Usually the unit has a level detector, which stops the motor when the tank is full up and then you have to remove and empty it.

This can be a tricky operation with some models, as lifting the tank out of the unit without the water slopping over the side is a task more suited for a summer’s fete competition.

Evaporative coolers
Evaporative coolers can be used to cool the air in a room but they are not air conditioners. They work by blowing hot air from the room over a wet surface inside the unit and as the water evaporates from the surface, the temperature of the air is reduced. However, the outgoing air is now laden with moisture and so the room must be well ventilated otherwise the effect will soon be spoilt by the air becoming very humid. (As well as everything in the room becoming wet.) A wide-open window is really a minimum but a through passage of air between two windows or a door and window is better.

The unit has a tank that you fill with water and this is slowly emptied over the internal wet surface. Some models have provision for an icebox so that the air can be cooled further.

Similar to dehumidifiers described above, air conditioners employ the same operating principles and basic components as your home refrigerator. An air conditioner cools your home with a flow of air that has been cooled on a cold indoor coil called the evaporator. The condenser, a hot coil usually placed outdoors, releases the collected heat outside. The evaporator and condenser coils are made of tubing surrounded by aluminium fins. A pump, called the compressor, moves a heat transfer fluid (called a refrigerant) between the evaporator and the condenser. The pump forces the refrigerant through the circuit of tubing and fins in the coils. The liquid refrigerant evaporates in the indoor evaporator coil, pulling heat out of indoor air and thereby cooling the home. The hot refrigerant gas is pumped outdoors into the condenser where it reverts back to a liquid giving up its heat to the air flowing over the condenser's metal tubing and fins.

The basic types of air conditioners are: room air conditioners (usually but not necessarily portable); split-system central air conditioners where one part is outside and the other inside; and packaged central air conditioners.

Portable air conditioning units
The coolers and dehumidifiers described previously are useful to an extent but they lack the oomph of a true air conditioner. However, installing an air conditioning system at home can be expensive.

Portable air conditioning units bring the technology direct to the home, without the costs of installing a full system although as with a dehumidifier, you’ll need to find somewhere to put the unit.

Portable air conditioners cool rooms rather than the entire home. As they provide cooling only where they're needed, room air conditioners are less expensive to operate than central units, even though their efficiency is generally lower than that of central air conditioners.

When choosing a portable air conditioning unit, bear in mind the size of your room as you will need a unit with a suitable capacity, for example if you’ve got a big room, you’ll need an air conditioner with a greater capacity to ensure the room stays at the optimum temperature.

Air conditioner capacity is defined in BTU’s (British Thermal Units). The dimensions of your room will determine what capacity air conditioner you need. A good suggestion would be:

Room size:

15ft x 13 ft 8000 BTU
17ft x 14 ft 10,000 BTU
20ft x 15ft 12,000 BTU

Note:

If the room is heavily shaded reduce the capacity by 10%
If the room is very sunny increase the capacity by 10%
If the unit is for the kitchen, increase the capacity by 4,000 BTU
If a permanently open doorway connects one room to another, consider the two rooms as one.

Some smaller-capacity units will have a condensation bucket to empty, where larger units will have an exhaust hose, which like a tumble drier must be vented outdoors either through an open window or through a specially created hole in the house wall. This will need to be taken into account when you look for a suitable position for the unit in your home.

The outside venting requirement may seem a disadvantage, particularly as opening a window and running a cooler may seem contradictory. However, any model of dehumidifier or air conditioner that does not have an outside connection of some sort will eventually further heat up the room. The air coming from the unit may feel cool but you can’t use all that electricity without the heat from the motor and the heat extracted from the cooled air going somewhere. In a closed room it can only end up heating the room.

Unless you buy a unit of sufficient capacity to cool several rooms don’t forget that you’ll need to keep the room door closed. A separate fan may also be useful to move cooled air around a larger sized room.

One air conditioning manufacturer, Airconco has a convenient calculator at www.airconco.com that will tell you the size of air conditioner you will need for any size of room or office for various conditions of use. For example, large south-facing windowed rooms need a more powerful unit to ensure effective cooling on sunny days.

Features to look for

Multi-function. i.e. air conditioner, fan & dehumidifier.
Check the capacity is suitable for the largest room you’ll want to use it in.
Check the physical size and where you’ll locate it.
Settings for temperature.
Possibly remote control, very useful in a bedroom.
Timer for controlling the unit before you get home.
Fan speed settings, three minimum.
Adjustable louvres to direct the airflow.
Check the noise level, usually quoted as a dBa figure. The lower the figure the quieter the noise level.
Some models have an air filter to remove pollen.
Check the type of condensation removal – bucket or hose. Note that some models re-use condensation to help cool the air, similar to the evaporation coolers described above. These types may be less effective at removing humidity from the room.
Environmentally friendly with CFC free components.

Fitted air conditioning units
There are principally two types of fitted systems. One type, generally called central air conditioners, circulate cool air through a system of supply and return ducts (i.e., openings in the walls, floors, or ceilings covered by grills) carrying cooled air from the air conditioner to the home. The air conditioner and it’s attendant noise is conveniently situated outside the home or in an outhouse. This type of system really has to be designed and allowed for as part of the home design.

Split-system central air conditioners on the other hand can be retrofitted, although it’s better and easier to fit the insulated pipe-work when the house is constructed.

In a split-system central air conditioner, often called a ductless system, an outdoor metal cabinet contains the condenser and compressor, and an indoor cabinet contains the evaporator. Insulated metal tubing joins the two halves of the system and one outdoor part can feed several indoor units. The major advantages are that the indoor parts are small and convenient, a bit like radiators to look at (indeed, often they can also be used for heating in the winter) and the noise and heat is all kept outside.

The amount of cold air entering the room can he controlled by a thermostat or it can be regulated by an infra-red remote controller, like a TV remote. One room or one area of a building can maintain a different temperature from another room or area in the same building thereby satisfying varying comfort levels.

It’s unlikely that you will have time to fit split-system air conditioner to your home during this particular heat-wave, but don’t forget it. One day all UK homes will be fitted with them as a matter of course. Heaven knows what the summer temperatures in the Mediterranean will be by then, but for sure, they’ll have bigger air conditioners to cope!