There is, says Bill Rawson, Chairman of the Rawson Property Group, a growing call from prospective home owners for the incorporation of modern energy saving installations in any home, particularly a new one. Today, says Rawson, his own group’s Rawson Developers simply cannot go ahead without such systems being part of the offering.
Nevertheless, says Rawson, the general public, while coming round to accepting the need for such equipment, are often very ignorant as to the virtues and disadvantages of the various systems on offer.
There are, he says, basically two options open to those wishing to take this step and both operate primarily on the hot water systems. In commenting on this matter, he acknowledges the debt to Synergy Heat Pumps and Solar Hart systems who have been extremely efficient in providing accurate information relating to these products. Both solar heaters and heat pumps, says Rawson, have certain advantages and disadvantages and both are particularly suited to certain homes.
Heat pumps, which derive their energy from the heat in the atmosphere, may, for example, be ideal for a holiday home which is not occupied for more than a few months a year and is in a high humidity coastal area where the water is of a good quality. Solar heaters, by contrast, are likely to be suitable for almost all South African homes because, although reliant on sunshine, their backup systems ensure that they can provide sufficient hot water regardless of the quality or the weather conditions all the year round.
The chief advantages of heat pumps, says Rawson, are:
1. They do not need complicated plumbing and are therefore easy to install.
2. They do not have to be on the roof. They can in fact and often are installed out of doors, although it was to be borne in mind that the site must be north, east or west facing.
3. Working with electricity and having a backup system, they can be relied on to provide water round-the-clock every day of the year provided the Eskom supply is sustained and they are relatively inexpensive.
“The general opinion,” says Rawson, “is that heat pumps will save up to 50% of the energy required to heat hot water. This equates to a 20% to 30% saving of total energy costs, but this a far lower saving than will be brought about by a solar heater.”
The disadvantages of heat pumps, says Rawson, are that they are said to be less efficient in areas where water quality is ‘hard’. In these cases it is reported that carbon carbonate in the water solidifies at the bottom of the tank and then blocks the heat exchanger. Heat pumps can also be noisy and require regular maintenance every five to ten years.
Heat pumps are, in general, less efficient than solar systems, which will save up to 90% of energy costs. Solar systems are often the preferred equipment, especially in areas subject to very cold (sub 5 degree temperatures in winter), where a heat pump will lose 50% or more of its efficiency.
Solar heaters tend to have a far longer life span than heat pumps – in some cases over 20 years – and are not affected by ‘hard’ water. While solar heaters rely on sunshine, almost all systems have a backup which will ensure hot water supplies even on grey overcast days. Although installed on the roof, which many people consider unsightly, solar heaters today can often be supplied in a wide variety of colours which makes them relatively unobtrusive.
The major disadvantage of solar heaters is that they are far more costly than heat pumps, but, says Rawson, arrangements can usually be made with the supplier to pay off the cost of them over a period of several years and in general it seems to be agreed that the savings achieved by solar heaters will enable them to pay for themselves within three to four years.
