As with so many things in life, price is king. And air conditioners do vary tremendously in price. A small, window-mounted air conditioner might cost just a few hundred pounds. A large, sophisticated system on the other hand might cost many hundreds of thousands of pounds.
As well as the up-front price, we should also consider the efficiency with which the unit runs. A more expensive system might, over time, justify itself on the basis that it’s able to do its job better, and use less energy in the process.
Air-conditioners which are housed entirely within a single small unit are inherently less efficient because the evaporator and condenser coils (which respectively collect and disperse heat) are placed next to one another, and so the transfer of heat between the two is interfered with. Systems where the two sets of coils are housed in different units (which might be on the inside and the outside of a building) are inherently more efficient, often prove wise investments in the long-term, particularly when a lot of space needs to be air conditioned.
We’ve already established that larger air-conditioners are more efficient than smaller ones. But we should also consider the space we need to cool – after all, getting an air-conditioner that’s larger and more powerful than you need is wasteful.
The power of an air conditioner is measured in British Thermal Units. Generally speaking, you’ll need around 20 BTUs for each square foot of space you need cooled. This will give you a rather crude estimate of how much power you need. But you’ll also want to consider other factors, like how crowded a room is going to be, the extent to which the room receives sunlight, and any other sources of heat that might be present.
A crowded kitchen, for example, is going to require more cooling than an empty office – even if the two are of the same size. Add around 600 BTUs for each person that’ll be occupying the room, and around 4000 if the room is a kitchen. If two rooms aren’t separated by a door or other obstacle, then you’ll need to consider them both as a single space – after all, an air conditioner won’t be able to know the difference.
3. Installation Distance
We’ve already noted that housing the condenser and evaporator coils in separate units, on the inside and outside of a building, can yield improvements in efficiency – that’s why larger systems are designed in this way. But there is a trade-off, here.
If the two units are separated by a long length of tubing, then this will also impact the performance of the system as a whole. After all, the more distance the coolant has to travel, the more energy will be required to send it round the loop. A five-metre installation can be up to ten-percent more efficient than a fifteen-mere one, for example.
Of course, the installation distance will depend to a large extent on the physical makeup of the building. You’ll want a good idea of where to place your AC units so that this distance is kept to a minimum while still retaining your conditioner’s ability to disperse cold air around the interior. In some cases, you might want to install a ceiling fan in order to facilitate this dispersal while at the same time minimising the installation distance.
4. Health and Safety
In order to meet their health and safety obligations, employers will need to provide their staff (and customers) with a comfortable environment. This means temperature control in the form of fans, open windows, or air conditioning. Since the latter of these is by far the most efficient way to meet this obligation, it follows that an air conditioning system is a wise investment – particularly in cases where many employers are crammed into the same space. Of course, in order to keep the temperature manageable, you’ll need to ensure that your unit is regularly maintained.
When setting the temperature on your air conditioner, you’ll want to ensure that it’s not so low that your employees can’t properly function. The Health and Safety Executiverecommends a temperature of at least 16°C, or, if strenuous work is being performed, 13°C. For most office settings, the former guideline is preferable. A large disparity between the indoor and outdoor temperatures will drive the air conditioning hard. Ideally, you’ll want a difference of less than ten degrees Celsius.
Some air conditioners are noisier than others. Typically, this is because they’re less efficient, and so the fan needs to work harder into order to produce the required temperature. But you might also hear the sound of the motor, or of loose screws rattling as the unit gets older. Obviously, the best way to guard against these problems is to regularly maintain the unit.
Many modern air conditioners are run so quietly that you’ll only be able to hear the fan – and sometimes not even that. When comparing units, look for the ‘dbA’ rating – while being aware that small changes in this rating can result in massive changes in perceived volume. Most air conditioners are around the 50dbA mark – but if you’re going to have yours installed in a noise-sensitive place, like a bedroom, then you might shop around for something quieter.