CLEANER FOSSIL FUELS

Let sunshine add to savings – with solar power

From affordable homes to luxury condos, energy saving construction techniques are invaluable, and energy-efficient houses cut costs, are environmentally responsible and aesthetically pleasing, states SANEDI.

When building an energy efficient house, the first consideration is the best way to achieve cooling and heating, without ‘money’ evaporating into the air. Cool Surfaces roof coatings, formulated for South African conditions, can reduce internal temperatures by as much as 2-4 degrees, as SANEDI has proven in largescale informal housing settlements.

Heating water can use 30-40% of the electricity bill. Incorporating interventions at the start of the design work ensures that energy saving technology is built into the cost of the house.

Solar thermal (ST) systems provide hot water and solar photovoltaic (PV) systems generate electricity for the household. Both systems are coming down in costs and payback period (on average, 5-7 years) and homeowners are encouraged to include these systems into the financing at construction stage, rather than as an add-on.

Cool Surfaces refer to materials and technologies, such as white roofs, light-coloured pavements and specialised cool coatings used in the construction of the building envelope to improve thermal comfort through surfaces that reflect much of the solar energy and release much of the stored heat energy. Solar thermal systems are well known in the South African low-cost housing market, and most are thermosyphon systems, relatively small in scale and not needing electricity for a pump or an electronic control, so they can be used without access to the electricity grid.

PV solar panels absorb and convert sunlight into electricity, a solar inverter changes the electric current from DC to AC, connecting to the house wiring. A battery storage system allows for days without sunshine, though this is an expensive option that should be included in the original finance deal. As disconnecting from the national grid would not remove the monthly charges to the homeowner by the local utility, a complete off-grid option is not practical at this stage.

SANEDI states that the installation of solar systems in the construction of housing developments is a step in the right direction in the fight to conserve natural resources, save money on utilities and combat the negative effects of climate change. The prices of these technologies have reduced significantly over the past five years and the technology has evolved in terms of quality.

SMART BUILDINGS boost energy efficiency

What once was science fiction is now an everyday reality for many thanks to digitalisation, and this trend is set to continue.

Examples are lights only operating when someone is present; central air conditioners creating climate zones for differing comfort levels; banks of computers or other machines being ‘put to sleep’ after a period of non-activity; lifts only switching on lights when called; underground carparks remaining dark until movement occurs; and so on. The Fourth Industrial Revolution (Industry 4.0) is driving energy efficiency as increasingly devices become digitalised. The Internet of Things (IoT) includes the refrigerator in the home, the aircon in the office and the entire production process in the factory. The more efficiently these run, the less energy is expended.

Building management systems are becoming commonplace, and not just for offices; smaller versions are available to be wired into the home’s distribution board. These can be used to shut down what industry terms ‘vampire loads’ – the plugs with indicator lights that are not in use but on standby or any appliance using clocks or readouts when not in use – which can be put into ‘sleep’ mode.

Mobile phone apps, when coupled to the right technologies, can switch on and off lights, heaters and air conditioners, or activate the microwave from a smart phone.

Ways to save SANEDI highlights further tangible ways that the country can cut down electricity usage to help meet South Africa’s energy demands, from simple everyday actions to more effective ways. • Turning lights off when they’re not being used and exchanging regular globes with energy-saving globes • Heating water is one of the most energy-intensive and one of the most expensive processes. Reduce geyser temperature to below 60°C – this will mean less cold water will need to be added for showers and dish-washing. • Insulating the geyser and outlet pipes will also help to keep the water warm for longer. • For cooking, using a microwave rather than an oven will take half the time and consume half the energy. Braaiing or using a gas stove save even more energy. When cooking on electric hobs, match the pan size to the element size, and keep the lid on the pot when cooking. • Using a dishwasher rather than washing by hand saves electricity and water. Hand-washing a 12-piece dinner service can consume 2.5kWh of electricity and 103 litres of water. The same load in a dishwasher will use 1.05kWh of electricity and 12 litres of water. • For washing machines, use a 40°C wash cycle rather than 60°C, which equates to a 30% electricity saving, and skipping the pre-wash cycle will use up to 20% less electricity. • Dry clothes naturally rather than using a tumble dryer. • When buying new appliances, make sure they carry the Energy Efficiency label, preferably rated with an A-rating. • In the office, turn off printers, copiers and fax machines when they are not in use – don’t rely on sleep mode. • Using power management on your desktop computer can save 900 kWh a year, amounting to more than 680kg of carbon dioxide emissions.