In homes, all incandescent bulbs – mainly candle bulbs in chandeliers and bedside lights – can be changed to compact fluorescents (CFL). Payback on LED bulbs for lights that operate for approximately five hours per day is typically four to six months. Building a habit of switching off lights when a room is not occupied will also reduce consumption.
It is worth taking a look at down lights too as many are still 40 to 45 watt bulbs. They can be replaced with 3W LED bulbs, which are now available.
Geysers typically account for 40-60% of the electricity consumed in a home. Simply changing the temperature of from 80°C to 55°C will see a saving of 50-100kWh per month. The benefits of installing a geyser timer can be material, but much will depend on a household’s individual circumstances. Where there is a clear benefit, however, is in switching off the geyser at the mains if you are away for two or more days at a time. The simple insulation of a geyser with a blanket will also yield a drop in electricity consumption.
Fitting a geyser with a heat pump can save 60% of the geyser electricity consumption. This means that, at a price of an estimate R16 000 installed, the payback would be between four and six years under current electricity tariffs. With estimated price increases in the next few years, the payback period will likely be three to four years. One downside, though: heat pumps are noisy.
At a similar price to heat pumps (R16 000 to R20 000), paybacks will be around the same (four years). Solar geysers are silent and work well, but can be more expensive than heat pumps and is not always suitable (when there isn’t enough sunlight, for example).
Washing laundry in cold water costs nothing and the savings can be quite substantial, although this will vary from machine to machine. Some appliance makers estimate that 75-90% of all the energy used by a washing machine goes to warming up the water.
Changing from a chest freezer and an inefficient old fridge to a new, energy efficient fridge/freezer combo can save 150kWh per month. In one of the households above, the saving was 100-150kWh per month. At the cost of R7 000 for a new appliance, the payback is approximately three years.
Gas cooking and heating
These calculations are more difficult to do, as patterns will vary from household to household.
A 9kg gas cylinder, at just over R200, will power a stove for three to six months, depending on how often it is used. This equates to R30-R60 per month for stove-top cooking.
Electric bar/fan/oil heaters should be avoided at all costs.
The installation of a solar system to augment or replace grid supply is an obvious option. There is the added benefit of avoiding the impact of any load-shedding or power outages. Here, however, there is no cookie-cutter solution. Each installation has to be correctly sized for the particular house and its typical electricity consumption pattern.
It is worth doing this exercise and figuring out whether the investment makes sense. Some households are seeing payback in approximately three years, while for others (particularly those who rushed to solar before prices really dropped) the payback period is longer.
Source: Hilton Tarrant at MoneyWeb