Case Study: Simbithi Eco Estate

Project type: H4 residential property

Location: Simbithi Eco Estate, Ballito, KwaZulu Natal

Climate Zone: 05

Assessment Methodology: SANS 10400XA 4.2.1c Reference Building Route

Property Gross Floor Area: 313m2

Property Net Floor Area: 276m2

Property Percentage Glazing to Net Floor Area: 70.15%

Reference Building Demand and Consumption figures:

Annual Energy Consumption: 298.8 kWh/m2/annum

Peak Energy Demand: 79.60 VA/m2

Improved Building Demand and Consumption figures:

Annual Energy Consumption: 285.10 kWh/m2/annum

Peak Energy Demand: 74.90 VA/m2

Estimated cost saving to client: R600,000


The property had extensive glazing on its North East facing fašade which resulted in heavy solar heat gains throughout the day. The client brief was to develop the most energy-efficient compliant building at the most cost-effective price.

The base-line Reference Building would be required to have triple-glazed tinted glass in thermally broken window frames and additional shading beyond that contemplated in the design in order to achieve compliance with the SANS 204 prescriptive fenestration requirements.

SANS 10400XA compliance was achieved with single-glazed glass throughout. Although clear glass was proven to be regulatory compliant the internal heat loads suggested that greater energy efficiency and reduced long-term running costs would be achieved by using tinted glass in the windows. Lighting was maintained at 5W/m2, cavity wall construction was recommended, heat pumps (average CoP of 3.0) were utilised for the hot water generation. Reverse cycle inverter type air-conditioning (average CoP of 3.3) was required to maintain internal levels of thermal comfort.