The most energy efficient windows in South Africa Since 2007 the price we pay for energy has skyrocketed by over 400%. The solution is not more energy generation, but better, more efficient use of what we have. As a result the Government now requires all new commercial and residential developments, including renovations, to use energy efficient windows. Teva has a fresh view on the world we now live in, offering the most energy efficient windows and doors available in South Africa. They're made from white uPVC imported from Rehau in Germany, custom designed for harsh South African conditions.