How many buildings have been certified by the German standard (DGNB)?
- In Germany the certified buildings together with those which are going to be certificated by the German standard are about 150. Six are by BREEAM and about ten are certified by LEED.

How is the German certification system different comparing to the others?
- The difference is that on the one hand we talk about a green certificate on the other it is a sustainable certificate. First we have the environmental issue in its major part and then the economic and the social aspect. The other certification systems do not touch the economic issue. The other certification systems have points which could earn a certification level and in the German system you have to find your own solution to get an outcome, for example the temperature for a room.

Is it hard to obtain for example a silver certificate or to upgrade from silver to a gold certificate?
- It is getting harder and harder. For example Germany has high standard in terms of energy when you build a new building that are becoming higher and higher every 3-5 years. And you have to be better than all these standards to get a bronze DGNB certificate. To obtain a gold certificate you have to do a lot better than that and it is a major step.

If you have two buildings – gold and silver, which one will be filled faster with tenants?
- It depends on what the tenants want to achieve. If they have a policy to be in a certified building it sometimes does not matter for them if it is silver or gold and they look at the price. If they have a policy that they have to be gold then the price is not a major issue for them.

What is the average price difference between the rent for silver and gold certified buildings?
- I can’t say that because it depends on how innovative people are to get the solution. Sometimes it can be even cheaper to get a new solution and you typically get more points for a new solution. If you are very innovative then you may achieve better rates.

Suppose we have a 10-year old building which has been build according to the top standards ten years ago, could it be certified with the German system?
- Yes, it is possible. You have to use the standard for existing buildings. You should take the information about the energy consumption, the materials, how much it costs to run the building, to clean it etc. and than you have to compare it to the current benchmarks in the area to see what level of certificate you could obtain.

If you have A level energy label will the building get easier a gold or a silver certificate?
- Yes it will be easier because you have already done work on the ecological part but it is expensive and you will lose on the economical part, but normally it is easier.

Which types of building can be certified?
- Office was the first than we did retail, logistic and residential. Now we are trying to finish hotels and hospitals for example. Now we are also trying to certify a whole urban area. We can certify an existing office building and the next one will be an existing residential building.

How much does it cost to certify the building?
- If we talk in percentage I would say about 1% of the actual building cost on average.

This is not such a considerable amount. So why is the number of the certified buildings so small?
- Sometimes when the building is getting bigger this 1% represents a high cost but I believe that in the future almost every new building will be certified.

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Prof. Dr.-Ing. Kunibert Lennerts

Prof. Dr.-Ing. Kunibert Lennerts teaches Facility Management in the Technical University Karlsruhe from 2000. Before that he is head of the FM department of the biggest railway company in Europe – Deutsche Bahn, and has managed unique heterogeneous building stock. He is the first facility management professor in Germany.