One thing that will hopefully be spurred by the ASHRAE BEMP certification is availability of training for energy modelers which should help in your question about quality of modeling. Your concern there isn't limited to South Africa!

Perhaps South Africa might also provide some default weather files similar to those used for simulations in the climate zones of California for use in this compliance exercise? I'm not personally familiar enough with the climate in South Africa to know how many standard weather files would be enough to cover the country adequately. That could remove one variable from the process to maintain quality.

Material libraries for several simulation programs shouldn't be that hard either unless there is some great variance from what people are using in other locations.

David