Know your number

MGH Green_smallZwelethu and Bulelwa Ngewana, along with their children, have measured their home’s energy consumption in an innovative way, declaring that they use 41 kilowatts hours per square meter per year (kWh/m2/year) in their home. They are challenging themselves to cut this figure by 40 percent, while asking other South Africans to see how they measure up.

The My Green Home website,, shows South Africans how to calculate their own kWh/m2/yr number as a first step toward lowering energy consumption. This measurement is widespread internationally, but in South Africa the Ngewanas are almost certainly the first family to go public with their number.

My Green Home is led by the Green Building Council South Africa, with main co-funding from the German government through the South African-German Energy Programme (SAGEN). It’s also supported by the 49M campaign, the South African National Energy Development Institute (SANEDI) and a range of product sponsors and partner organisations.

Over the next three months, My Green Home will guide South Africans through no-cost, low-cost and invest-to-save ways to green their homes, with 12 weekly themes such as hot water and lighting. The first of these is titled ‘Start by Measuring’. Those who wish to follow this journey are encouraged to work out their starting point as a first step toward saving.

The website also provides tools to guide participants through another measuring method: the eco-audit. Easy online eco-audits help determine where electricity and water is being used most in the home. The Ngewanas discovered that their geyser and pool pump together accounted for more than half of their electricity consumption. That is set to change as the Ngewana’s home undergoes a major energy efficiency and green retrofit this month.

Those who participate stand a chance to win green prizes, including the grand prize: their own ‘green home makeover’. Anyone who identifies where they consume the most electricity at home or calculates their kWh/m2/yearnumber and submits a related ‘selfie’ photo to the website or Twitter (@mygreenhomesa) is eligible for the first week’s prizes in a random draw on Monday 19th May, as well as the grand prize in July. Details on this first competition are available on the My Green Home website.

Grace: “I did the calculation at my home in Edgemead and my number is 23.  I already have LED lights, use my hotbox and induction stove if I cook, switch off when not needed and grab the blanket instead of the heater.  I am not sure how I can reduce this besides looking at invest to save options, but the irony is that with such a low consumption (Lifelife 1 tariff, on average about R115 per month) it makes any return on investment very difficult…”

Also on the website, in another first, the Ngewana’s electricity consumption is displayed on a live dashboard , with real-time consumption of their geyser, pool, laundry, lights, stove and outlet sockets each individually metered. Theirs is surely the most intensely monitored house in the country. For the trend-setting Ngewana family, it is just the beginning.

Installation of eight different meters for live energy monitoring.

Installation of eight different meters for live energy monitoring.


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