Recently, we spoke with Dr. Tobias Bube from Rolf Disch Architecture regarding the potential for net-zero-energy design in residential construction. Rolf Disch has been involved in net zero or “plus energy” architecture since 1994. The firm’s first building, Heliotrope in Freiburg, Germany is widely considered by a number of architects to be the first building in the world that produces more energy than it consumes.
Dr. Bube told us that the additional cost for constructing a net-zero-energy home is only 7% to 10% more than that for construction meeting the minimum energy efficiency standards required by codes in Germany, such as EnEV 2009. Dr. Bube added that net-zero-energy construction can reduce heating and cooling costs by 90% for a 100 m2 home, bringing the payback period for energy conservation technologies under 10 years.
Rolf Disch utilizes technologies such as daylighting, passive solar heating, insulation better than R 10/inch, and zoning in windows. It also uses solar photovoltaic (PV) energy for on-site generation and payback for the PV technologies is in excess of 20 years with the recent reduction in German feed-in tariffs (FiT) for solar. Over the years, Rolf Disch has faced difficulties convincing home builders and housing development companies to adopt net zero or plus energy design. Therefore, in 2003, the company decided to float its own housing development arm adopting plus-energy construction methods. It now serves as the main customer for the design firm. According to Dr. Bube, a significant slice of the German upper-middle class is prepared to pay a premium for plus-energy homes.
According to our estimate, over 300 net-zero-energy buildings (NZEB) have been constructed over the past 10 years, most of them being in the commercial and institutional sector. Low tolerance for high capital expenditures and long paybacks have both held back the adoption of NZEBs in the residential sector. But a combination of high electricity prices, strict building energy conservation codes have made Germany the first geography where NZEBs can potentially take root even in the residential segment. Investors interested in the NZEB space should follow the activities of major home builders and housing development companies in Germany.