Eskom has contracted Ellies Renewables, a division of JSE-listed Ellies, to install low flow showerheads and geyser timers to residential households who apply and are within the Ellies installation areas. These showerheads and timers will be provided and installed at no cost to the households.
The timers, which reduce the heat and energy losses that occur when the water in the geyser is kept at high temperatures for 24 hours a day, allow for the water to be heated just before it is needed. They are optional for electric geysers but standard on all solar water heating (SWH) systems (they have a solar setting). Low flow showerheads reduce hot water usage and therefore electricity usage.
For example, a typical showerhead uses 15-25 litres a minute at 400 kPa. In high income houses, the pressure of 400 kPa is the equivalent to water flowing from a tank on top of a 12-storey building. The higher the system pressure, the greater the volume of water that flows from the showerhead. A low flow showerhead is designed to let less water through, but to give the same sensation of a good shower. This is achieved through smaller holes with better spray patterns from the showerhead.
The first impact of installing these two items will be to reduce the amount of water the household uses, and consequently the amount of hot water required to be heated. As a result of this saving, it is highly likely that a smaller – and therefore less expensive – SWH geyser will be suitable, and therefore specified and installed, for households that opt to replace their electric geyser with a SWH system.
The second impact will be that the geyser timers will already be installed in some of the households electing to switch to a SWH. This will reduce the cost of installing the SWH system and potentially the cost of the Electrical Certificate of Compliance.
Under the Ellies contract, the geyser timers are installed by qualified electricians.
For households to access the free installations, visit http://www.elliesrenewable.co.za/form/ and register directly with Ellies.
SESSA, the Sustainable Energy Society of Southern Africa, welcomes this programme, as each step to reduce the amount of electricity needed to heat water is a positive step for our country and its renewable and sustainable energy industry.
When households have reduced their hot water demand and reduced the heat losses from the geyser and pipes with a geyser blanket and insulation, a SWH becomes an even better investment. This is illustrated by the following case scenarios.
Before installation of showerhead, timer and geyser blanket:
A household of 4 people each having one 4-minute shower a day will typically use 20 litres a minute per shower and a 200 litre electric geyser. The energy used will amount to 4400 kWh a year, or R6116 a year given the homelight tariff of R1.39 per kWh including VAT. With the current water usage because of the high flow showerhead, should the household elect to install a SWH, it would require a 300 litre SWH system.
After installation of showerhead, timer and geyser blanket:
The same household of 4 people will now each take one 6-minute shower a day using 9.5 litres a minute per shower, and a 200 litre electric geyser. The 6 minute shower time is an extra allowance because experience shows that some people shower longer with a low flow showerhead. The energy used will amount to 2926 kWh a year, or R 4170 a year at the same homelight tariff. Should this household, now with a low flow showerhead, opt to install a SWH system, it would only need a 200 litre solar water system.
So, installing the low flow showerhead, timer and geyser blanket saves 1474 kWh a year and R1946. In addition, should the household elect to install a SWH system, it will require only a 200 litre system, saving up to R10 000 in capital costs.
In conclusion, changing from a high to a low flow showerhead can reduce total hot water usage by as much as 1000 kWh a year. This will allow a smaller SWH to be installed when the household adopts that technology. Improved hot water management through using a timer, and improved heat retention through using a geyser blanket further, serves to allow a smaller SWH system to be installed. As a result, the rands and cents argument for SWH is strengthened.
It is critical to note that if the household uses baths rather than showers, this will change the consumption substantially.
This program will reduce electricity and water usage and make SWH more affordable. It will also boost the return on investment in a SWH system – at 2012 rates the return on investment is around 40% after five years and 140 % after 10 years. See www.sessa.org.za for more details.
By Robin Thomson. Thomson holds a B Sc Mech Eng and an MBA – both from University of Cape Town. He is the Technical Specialist for SESSA, the Sustainable Energy Society of Southern Africa.
Water and energy usage before changing showerhead, installing timer and geyser blanket:
|No of showers||Minutes per shower||Showerhead litres per minute||Mixed Water Temp °C||Hot Water Temp °C||Cold Water Temp °C||Daily kWh||Annual kWh|
|Losses @ 3 kWh per day||1095|
|Total cost||R 1.39||R 6 162.61|
Water and energy usage after changing showerhead, installing timer and geyser blanket:
|No of showers||Minutes per shower||Showerhead litres per minute||Mixed||Hot||Cold||Daily kWh||Annual kWh|
|Losses @ 1.5 kWh per day||547.5|
|Total cost||1.39||R 4 067.42|
Annual electricity (kWh) savings achieved by the interventions:
|Annual Savings from reduced usage||959.8|
|Annual Savings Reduced losses from using timer – 1 kWh per day||365.0|
|Annual savings from blanket 0.5 kWh per day||182.5|
|Total annual savings from timer, geyser blanket and showerhead||1507.3|