I suggest you look at the price development of residential real estate comparatively over a longer period of time, say 15 years:
Real estate prices in Germany have increased very little over that time period. See the graph at:
http://ebinvesting.com/2012/07/02/more-real-estate-trouble-for-the-euro…
Due to the introduction of the Euro Spain for example was able borrow money at much lower rates then before. This led to the real estate bubbles in Spain. In Germany interst rates did not change much and nor did real estate prices. The link below is to Prof. Sinn's explanation, unfortunately I couldn't find a presentation in English.