We unpack the latest two certified EDGE project- The Crossberry-Cussonia and Devland Gardens

Words Chris Erasmus

On the

In total, there are 194 countries that have submitted Nationally Determined Contributions (NDCs) to reach their targets of reduced emissions through climate solutions, to help achieve the objectives of the Paris Agreement. A 50% reduction in global building emissions is needed by 2030 in addition to achieving zero-carbon emissions by 2050.

To achieve these ambitious goals, investors, developers and governments need to work together to meet the demand for buildings in a way that is economically beneficial and aligned with global climate goals. More evidence will help significantly to provide quantifiable proof to back the business case for green buildings in emerging markets, which will release a new wave of investors and developers taking leadership of the sector.

Green initiatives can be approached in two ways on affordable housing projects. On a macro scale, governments can offshoot green building growth through progressive policies. The creation of both fiscal and non-fiscal incentives that are tied to certified buildings can create massive awareness among the developer community and galvanise markets into action. Incentives are particularly impactful when layered upon a building code policy at the municipal or national level that is well implemented and enforced.

“On a macro scale, town planning plays an important role in making a community as opposed to another standard housing project,” says Eloshan Naicker, Green Star accredited professional (new building) and Edge-accredited professional, technical director, previously from IFC. Some ways that this can be done is with the inclusion of recreational spaces. These can reduce stress and encourage communal growth. Storm water management across a site reduces the risk of flooding and the water can be collected and used within recreational spaces or in times of drought.

Façade of Crossberry Central.

“Communal recycling facilities and waste management can stimulate job creation and reduce waste going to already stretched landfill sites. Solar powered streetlights save on electrical supply and make streets safer,” he says. Locating housing projects close to public transport nodes and efficient movement networks within the communities makes commuting easier and safer.

On a micro scale, simple design and construction methods are easily achievable. Water can be collected from roof gutters for flushing toilets and watering gardens or in times of water shortages. Low-flow sanitary fittings are affordable and significantly reduce the demand on water supply.

Light-emitting diode (LED) lighting can be used throughout the home to save on electricity. LEDs consume less power and thus last longer. Investing in solar and other renewable energy means gives you a saving of about 2.5 less kW. “A typical three-bedroomed home that just runs off solar with LED will cost about R30 000 to R55 000 depending on how you use it. If you don’t use LEDs, it may cost around R80 000 to R120 000.”

A heat pump is an energy-efficient water heater that removes free heat energy from the surrounding air and transfers this to the water in your geyser. Affordable, low-capacity domestic heat pumps (3.8kW or less) can be combined with an affordable geyser (100ℓ or 150ℓ) to create an efficient means of heating water.

The International Finance Corporation (IFC), a member of the World Bank group, developed the EDGE (Excellence in Design for Greater Efficiency) tool, which provides for 38 specification enhancements. By selecting some 14 of these enhancements it is possible to achieve the required savings.

Aimed at any type of build, the EDGE tool is perhaps especially relevant for large-scale builds for the low-end of the housing market where, in South Africa as with many countries still in developmental phases, there is the greatest demand and where energy and water consumption savings are likely to be greatest and most effective.
The social housing market, for example, deals with households earning between R3 500 and
R15 000 per month. Reduced utility costs through EDGE interventions not only help such households to consume less water and electricity, but also shows how to manage consumption and utility costs. The process having been tried and tested successfully, most of the South African banks are now on board to provide preferential funding for buyers of EDGE certified units.


Looking into the operations of one of the players in the low-income housing market that uses EDGE tools to enhance outcomes for both developers and tenants helps illustrate the point.

International Housing Solutions (IHS) is an equity investor in affordable housing projects with a market value of less than R850 000 per unit. Since 2007, IHS has invested in about 40 000 affordable housing units in South Africa, Namibia and Botswana and has recently obtained approval of funding to invest in Kenya.

As one of the investors, the IFC required that IHS developed 5 700 residential units meeting EDGE post construction certification requirements. EDGE post construction certification requires that a unit must be redesigned to ensure at least a 20% saving of energy consumption, 20% saving of water consumption and 20% saving of embodied energy to manufacture materials compared to what standard building specifications would achieve.

Currently, IHS has invested in 24 projects consisting of 6 851 units which obtained EDGE preliminary design certification in South Africa, of which 12 projects, consisting of 3 201 units, have already achieved EDGE post construction certification.

These following two projects are the latest two EDGE certifications awarded by the GBCSA.


This project, consisting of 372 residential units constructed in three-storey blocks, is located near the Gautrain Midrand station in Johannesburg.

The units consist of two different typologies. The following table illustrates savings that were estimated as well as the actual savings achieved according to the monthly monitoring information:

Crossberry-Cussonia lounge.
Crossberry-Cussonia bedroom.

Base Case savings refers to the estimated consumption if the design and specifications meet the current building regulations. The Final Case savings is the consumption as calculated by the EDGE tool, if the design and specifications are enhanced using the interventions as listed in the EDGE tool. The actual consumption refers to the average actual consumption per unit over the last 12 months, as recorded by a prepaid metering or smart metering system. PV panels are used to provide most of the electricity used by the geysers to provide hot water.

Devland Gardens

Devland Gardens consists of 870 social housing units located south-west of Johannesburg. The units consist of five different typologies and are constructed in two phases. Phase 1a, consisting of 330 units (three typologies only) has been completed and received EDGE post construction certification.

As lease-up of phase 1a is still in progress, it is not possible to provide accurate actual consumption data to compare with the Final Case estimated consumption information. Accurate data will only be available once the units are fully occupied, and data for 12 months is available.

Typical block and walkway façade at Devland Gardens.

The following table shows the detail of the various typologies of phase 1a, as well as the estimate consumption for the Base Case and Final Case estimates:

A centralised heat pump system is used to provide hot water. Devland is developed and managed in partnership with Instratin Properties.

Low build costs

The additional construction cost to achieve the required savings was initially estimated at about
R17 500 per unit or about 2.5% of the development cost. By understanding the interventions better, and selecting the most effective low-cost interventions, the additional development cost to achieve EDGE post construction certification has been reduced to about 0.5% of total development cost.

The annual savings in utility costs for the tenants are about equal to the rent payable for one month. It is also considered important that the banks provide a green bond at lower interest rates to promote affordable ownership of EDGE post construction certified units.

“By using the design enhancements as recommended in the EDGE tool, it is relatively easy and much more cost-effective to design a residential unit to save energy and water consumption and reduce the embodied energy to manufacture the material required for constructing the unit,” says Willem Odendaal, technical specialist on the two projects.

Considering the general shortage of electricity supply, as well as water provision by the local authorities, a simple and cheap solution is to change the building regulations in line with the recommendations in the EDGE tool. The sustainability of the EDGE programme is considered important.

EDGE really makes green certification achievable for all. It is simple to use, cost-effective and internationally recognised.

Tenants, owners and property managers need to be trained to understand the benefits of living in an EDGE post construction certified unit to enable them to maintain the intervention, such as not replacing the LED bulbs with incandescent bulbs. To assist with the rollout of the EDGE programme, the training of about 500 developers, professionals and property managers by GBCSA was funded by investor KfW.

“EDGE really makes green certification achievable for all. It is simple to use, cost-effective and internationally recognised,” adds Yvonne Pelser of Inside Out Consulting, who also worked on the projects. “In addition to the green credentials, it really makes a difference on the ground, by helping the social housing tenants at Devland save on the consumption of utilities and also reducing utility bills.”