Two solutions will help to achieve the goal: comprehensive building renovation and the increased use of renewable energy in them. Both of these measures can reduce primary energy consumption in the building stock by 80 percent compared to today. Total annual costs for both measures are nearly the same, according to model calculations done for UBA.
The UBA study examines three so-called 'target states' which describe the building stock in 2050. Each scenario assumes a different degree of renovation and differs in the amounts of final energy that are still consumed after renovation and how high the share of renewable energy would have to be to count as "near climate-neutral". Maria Krautzberger said: "We recommend the renovation of buildings to the fullest extent possible. The more efficient buildings are, the more renewable energy becomes available for other purposes." The difference in power consumption alone in the individual 'target states' corresponds to the amount of electricity generated by all the wind power systems in Germany in 2014.
All three transformation pathways are very similar as concerns the buildings' CO2 emissions: a reduction ranging between 81 and 83 percent. There is also very little difference in total annual costs. Somewhat higher costs are incurred either for investment in the renovation or for the use of renewable energy.
The UBA commissioned the Klimaneutraler Gebäudebestand 2050 [Climate-neutral building stock 2050] project to the Öko-Institut. The study examines the building stock on two levels: individual buildings and the entire building stock. It describes the current status and expected developments in technology which will become available for the renovation of buildings: thermal insulation materials, ventilation systems, heating technologies, etc. Individual building standards ranging from the non-renovated building to the passive house were examined with a view to energy consumption and the costs incurred. The study also considered how compatible a nearly climate- neutral building stock is with the future energy system.
The Märkische Scholle housing cooperative in Berlin is demonstrating that it is already possible to renovate buildings and achieve climate neutrality through a pilot project under the Environmental Innovation Programme. Four of its multiple-family dwellings will be renovated by the end of 2016 and no longer generate CO2 emissions for heating and ventilation. Tenants will benefit from stable costs for living in their apartments.