Cooling for comfort
As the weather warms up, many of you are probably thinking about investing in air-conditioning for your home. Sydney is a place where reliance on artificial air-conditioning can be kept to a minimum and many Sydneysiders do without air-conditioning altogether. Good design to reduce solar intake in summer and facilitate cross-ventilation can assist in controlling the thermal environment within your home and might make air-conditioning unnecessary, which can only be a good thing. Artificial air-conditioning is expensive and needs a lot of power to run. Every year this dependence puts more and more pressure on the electric power grid causing power failures and placing strain on infrastructure and the environment.
Despite all this there will always be a place for air-conditioning in homes that cannot be kept cool by alternative means. Homes in high aircraft noise areas, for example, need to be able to keep windows and doors sealed in summer so air movement and cooling must be provided by an artificial system. Other homes that have not been designed with summer coolness in mind, such as those with large expanses of north or west-facing glass, might also need an artificial system.
The starting point when selecting a system will be whether to use refrigerative or evaporative cooling. Because evaporative cooling needs a low-humidity environment to operate it is not well suited to Sydney’s climate. Refrigerative systems also dehumidify the air, so they are generally the better option for this climate. Also known as heat pumps, refrigerative systems cool the air in your home by transferring the heat to the outside. There are various types of refrigerative coolers available ranging from individual units to fully ducted systems. The most basic unit involves mounting the whole system in the wall to expel hot air directly to the outside. In this instance, all the equipment is located in the one unit so these are a noisier option. Probably the most common domestic application is the split system, which is usually also wall-mounted but the noisy equipment can be located up to fifteen metres away outside the building. Good for cooling one space only, these can be a good solution for cooling individual living spaces or bedrooms.
If you want your whole home to be air-conditioned, ducted air-conditioning is your best, though most expensive, option. This involves installing a centralised air-conditioning plant, usually roof-mounted, which supplies cold air via ducting to your entire home. Zoned systems are the most energy-efficient as they allow you to cool only the areas of your home you are using, such as bedrooms at night and living areas during the day. Ducted systems require a certain amount of ceiling space to accommodate the ducting. It is also possible to supply air through floor ducting. This can be retro-fitted fairly easily if you have a suspended timber floor, but it’s almost impossible if your floor is a concrete slab. It might, however, be something to consider if you’re starting to build from scratch. Don’t forget that most local councils require the submission of a development application for installation of an air-conditioning system, especially where it has potential to impact on the amenity of your neighbours or will be visible from the street.
Refer to www.energyrating.gov.au for more assistance with selecting the right system for your home.
