Water and electricity bills covering a three-year period were analysed and found to average 0.8 m3 and 37 kWh per day respectively. These rates appeared particularly high when compared to the national average. Moreover, the electricity consumption in winter was higher than that in summer, which was in contrast with the local trend of the domestic sector that used more electricity in summer for space cooling. During the three-month duration of this investigation, electricity consumption was found to be highest for the electrical heater of the solar tank and this explained the peculiar increase in electricity consumption in winter. Table 2 shows the energy consumption for different appliance categories, as a percentage of the total daily demand.

Table 2. Electricity consumption by appliance category.

Appliance Category Electricity Consumption Percentage Share

IT Equipment (Internet, Printers, Laptop, etc.) 3.4%

Kitchen (Cooking, Fridge/Fridge-freezers, etc.) 25.6%

Artificial Lighting 20.7%

Laundry (Washing, Drying, Ironing, etc.) 3.5%

Audio / Visual Equipment (TV, DVD, etc.) 7.5%

Solar Water Heating Back-up Electrical Element 39.3%

The kitchen was the second highest area of electricity use due to the fact that no gas was utilised for cooking purposes. Artificial Lighting followed with a share of almost 21%, since most of the bulbs used were incandescents.

Approximately 5 kWh per day were consumed in stand-by mode, with 41% being attributed to Information Technology (IT) equipment (laptops, modems, printer, etc.) and the remaining 59% being consumed by audio-visual entertainment equipment (television sets, DVD players, etc.). It was noted that many appliances, which were in stand-by mode in the penthouse, were rarely being used.

While it is generally believed that solar water heaters (SWH), which replace traditional electrical boilers, could contribute towards a reduction in electricity consumption, a different picture unfolded during this auditing exercise. The back-up electrical heater was consuming 14.5 kWh per day, which led us to concentrate our investigations on the solar heater, as shown below.