Retrofit of Existing Subsidy Houses (RET)


Between 1994 and the start of 2001 over 1.1 million low cost houses were built with government subsidies that were provided under the Reconstruction and Development Programme (RDP) of the post-apartheid government that took office in 1994. These houses were built at low cost, but they are not designed for people with low incomes - they require high maintenance cost. No energy efficient building procedures have been used with the result that the overwhelming number (as high as 97% in some cold winter areas) of RDP housing occupants find their houses too cold in winter and too hot in summer. To overcome this deficiency occupants spend a large percentage of their limited resources on energy to achieve thermal comfort: a cost that could have been avoided with better planning.

Low-income house

The cumulative negative effect of the lack of thermal efficiency of low-cost housing is severe. Not only does it contribute to the energy crisis in South Africa, but it also negatively affects the health of the occupants as well as the ecology. For example, the 2004 FRIDGE report states that annual productivity losses and healthcare costs due to illness and death caused by air pollution in South Africa - of which pollution caused by households constitutes a substantial portion - could be set at R17.51 billion.

Retrofit of Existing Subsidy Houses

In the Retrofitting of Subsidy Housing Project (RET) we experiment with designs to improve the poor thermal performance of low-cost houses. It stands to reason that retrofitting will always be more costly, less efficient and more inconvenient than building properly in the first instance. The aim is to find ways in which existing low-income houses, that generally are extremely energy-inefficient, can be made efficient by way of retrofitting suitable technology:

The House Before RET Project 



In 2008 and 2010 Nova conducted feasibility studies in eMbalenhle and Zamdela on retrofitting insulation applications to existing houses. Some results (using Nova’s criteria) were:

  • Effectiveness Positive: the duration of daytime comfort levels achieved in the test houses were in some cases 217% higher than that of the control group
  • Desirability Positive, even dramatic: people felt better about themselves and about life as a whole
  • Affordability Negative: The cost of the application was too high
  • Sustainability Uncertain: needed to be monitored over time
  • Beneficiality Uncertain: the longer term impact on the health of the household as a system will be monitored over time
  • Repeatability Negative: due to high costs

Current pilot studies

Based on the results of the feasibility studies Nova redesigned the retrofit application and currently assesses the performance of it in two further studies. In the first study Nova retrofitted 505 RDP type houses in a high coal using area in Mpumalanga. In this study Nova deployed three different configurations of the retrofit application. Preliminary results point to a significant impact on coal use in certain configurations. In the second study Nova is studying the impact of the retrofit application in conjunction with coal stove replacement in 140 houses in another area of Mpumalanga. The results of this study are expected by mid-2016.

Reports available: Holm et al, 2008. Assessment on the Impact of Retrofitted Insulation Technology on the Quality of Life of Low-income households. Nova Institute: Pretoria.