Summary: When GESOBAU AG decided to modernize the 15,000 residential units it had built in the Märkisches Viertel locality of Berlin in the 1960s, it devised a three-point plan that would be both economical and repeatable elsewhere. It would re-skin the buildings to enhance energy conservation while also converting heating and hot water systems to environmentally friendly technologies. In addition, GESOBAU instructed tenants on how to operate their apartments for optimum energy conservation using new smart technologies. The first 538 apartments—shown here—were converted in 2008 and the project is due for completion in 2015. The primary energy saving as a result of the re-skinning is 71 percent of previous loads or 316 tonnes of CO2 annually.