The example of today’s total energy need of twelve apartments from 1896 in the old town of Basel shows what can be achieved economically and ecologically even in protected areas in European cities by an optimum PV integration and with high energy efficiency—despite "expensive PV”:
Scientific American loc cit. Jacobson and Deluchi, p. 64.
Today’s energy need of the apartments is 93% lower than before the refurbishment, and despite "expensive solar electricity”, the annual energy costs amount to only 19% of the former energy costs. a The difference of 27,200 € can be used for paying interests and amortisation of the energetic refurbishment investments without state subsidies. Such a difference in costs, however, is often not enough to finance all energetic refurbishment investments— especially due to cross-subsidisation of non-renewable energies. Therefore, compensatory payments are justified. b It is important to understand that energy efficiency accounts for 170,000 kWh/a and solar power for 37,200 kWh/a. c In the building sector making up for 50% of the world’s energy demand of 130,000 TWh/a, this combination of energy efficiency and PV energy production is unbeatable economically and ecologically. In order to substitute these 50% or 65,000 TWh/a, about 8600 nuclear power plants with a capacity of 1000 MW each would be necessary worldwide— at the moment there are approximately 430 NPP still in operation worldwide.