Green home. How can energy saving potential best be activated? Perpectives Interview

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1 Perpectives Interview Green home Prof. Werner Lang from the Technical University of Munich talks about energy efficiency and advocates the reuse of valuable building materials after the dismantling of buildings. Mr Prof. Lang, just the supply of energy to buildings generates around 33 percent of global CO2 emissions. On top of that there is the energy required for the construction, maintenance and dismantling of buildings. What are your thoughts, as an architect and sustainability expert, on this topic? It is absolutely essential that we fundamentally rethink our use of resources, meaning energy, material and water. With this in mind, the Association of Building Research and Professional Training under the umbrella of the Bavarian Building Industry Association founded, together with the Technical University of Munich, the endowment chair, of which I am the head. This endowment chair is a joint appointment between the Faculty of Architecture and the Engineering Faculty of Construction, Geography and Environment. This is another sign that points to climate-neutral construction as an interdisciplinary field. How can energy saving potential best be activated? Despite the immense tasks that lay ahead of us, one must point out: We have achieved a great deal over the last 30 to 40 years. Houses built in the 1970s needed 250 to 300 kilowatt hours of energy per year. Today, we are building passive homes with heat recovery, high-quality thermal insulating glass etc. which have an energy demand of 25 kilowatt hours/m2 per year. Generally it is most effective to activate the saving potential by using a combination of energy-efficient building envelopes, an energy-efficient base plate and intelligent building technology.

2 How many newly-constructed buildings are passive houses? At the moment, unfortunately only 10 percent. But from 2020 onward, all newly-constructed buildings will at least meet the passive house standard, meaning that they will produce more energy than they consume. How are we progressing with the energy-efficient restructuring of existing buildings? The fact that things are still moving forward extremely slowly in this area is due in greater part to social circumstances than technology. May older tenants live in existing buildings who have no desire to participate in comprehensive energetic retrofitting or are unable to. There are, however, other building owners who do not possess the necessary financial means or have set other priorities. We currently have a restructuring rate for old buildings in Germany of approximately 0.8 percent. However, we need to reach at least 2.0 percent to fulfil the requirements of the Paris Climate Protection Treaty. This has also already been ratified by the Bundestag and Bundesrat. Wouldn't we be able to achieve this goal faster if we focussed on the energetic renovation of entire boroughs instead of only individual objects? Theoretically, yes. But the boroughs vary greatly in terms of structure. It isn't possible to achieve cost-effective scaling effects or the cooperation of building owners in renovations anywhere you like. Let's take Munich as an example: Many areas in Ramersdorf feature the same facades and window and door formats. Here, cost scaling would be possible. Maxvorstadt, on the other hand, has barely any homogeneity. Nonetheless: Borough renovation returns large benefits in terms of energy efficiency, especially if you consider energy supply. A significant increase in efficiency occurs, for example, if an entire borough is connected to an existing district heating network, supplied by a combined heat and power plant or if a local heat network is achieved. Here, an energy use plan is helpful something that is already implemented by progressive communities. What role do building materials play when it comes to the energy efficiency of a building? A very big role, which is often misappropriated. Many building materials contain some amount of grey energy the primary energy required for the production, transport and disposal of the material. All of these factors are a part of the ecological balance. The material wood has virtually no grey energy. Steel, on the other hand, has a significant amount. If you build a house with a wooden facade but construct the underground garage with steelreinforced concrete, you negate the good ecological balance on the surface of house with a significant minus underground. The Energy Savings Regulation only focuses on energy consumption, which falls must too short. Currently, about ten percent of the building materials in buildings in Germany are recyclable. The target we need to achieve is 100 percent. Building planners need to plan the disposal of materials as well this is what Design for Disassembly stands for. Our chair is part of an EU research project called Building as Material Banks. This means that we need to build buildings as banks of material. The components need to retain their value after disassembly. How is your department involved in the relevant training courses at TU Munich?

3 The Faculty of Civil Engineering and Geodesy offers an interdisciplinary Master s Degree for energy-efficient and sustainable construction together with the Faculty of Architecture. With this course of study we have created an independent activity profile which bridges the existing gap between the traditional careers of civil engineer, architect and environmental engineer and paves the way for new career opportunities. In addition to those who have completed a Bachelor's degree in architecture, civil engineering and environmental engineering, those looking for a shift from different but suitable fields are also admitted to the programme. We also offer a lecture series called Sustainable Building and Technologies as an elective for students in the civil engineering and architecture programmes. There are, however, also mandatory courses on climate-optimized engineering included in the Bachelor's Degree. Energy-efficiency also complements the mandatory lecture on structural physics in the same way. On a global scale, which country is in the lead when it comes to energy-efficient building? German-speaking countries enjoy a very high degree of recognition worldwide when it comes to climate-neutral building. Of course, the declared abandonment of nuclear energy from 2022 onward in Germany presents a particular challenge regarding energy-efficient building. This makes Germany, in particular, a role model for other countries. In addition to projects currently being completed in German-speaking countries, there are also interesting initiatives and developments in climate-neutral construction in many other European countries and the USA. Building materials and the previously-mentioned Design for Disassembly both play a significant role in all of these projects. In your opinion, what are the lighthouse projects in the field of climate-neutral building? The commercial construction project 2226 is certainly a very ambitious project by the architecture firm Baumschlager Eberle in Lustenau, Vorarlberg, Austria. The number 2226 refers to the room temperature of between 22 and 26 degrees Celsius, which we perceive as very comfortable. The construction project in Vorarlberg will maintain these temperatures year-round without heating or cooling technology. This is achieved simply through the heat radiated by people, computers and lighting in the building as well as high-performance insulation and storage elements. There are also a few other interesting objects and projects in Vorarlberg. In this region, modern engineering skill and an old carpentry tradition have come together to form an ideal symbiosis for energy-efficient construction. In Germany, the eight-floor wooden house in Bad Aibling is worth mentioning. It is made of almost purely local coniferous wood. Only the stairwell needed to be constructed of concrete for fire protection reasons. It s construction was a cooperation between the Schankula architecture firm in Munich, local operators, the TU Munich and the University of Rosenheim. Another example is the Energy Efficient Center by the Center for Applied Energy Research in Würzburg a project in which I was also heavily involved. This object was constructed using modern, prototypical and even textile building materials, building system and technologies, all of which can be used for energy-efficient and resource-conserving construction. Thorough planning in the run-up to the project also illustrated how overall energy cycles can be positively controlled and optimised as early as in the planning stages. These days there is a lot of talk about smart homes. How do you define a smart home?

4 For me, a smart home is an extremely energy-efficient building which reacts intelligently to changes in temperature to reduce energy consumption and stores thermal energy in water-filled floors, for example, and does this even more intensively if colder temperatures are forecast for the next few days. Please take a glance at future developments: How will we be living in 100 years time? Allow me to shorten that period to 50 years in the future. By that time we will be living in buildings with selfregulating building envelopes which function robustly and as naturally as possible without any vulnerable electronic control technology. We will have intelligent usage of natural insulation and storage materials and several sensors, but also, of course, a building which is, from a electronic point of view, low-tech, but from a structural point of view, high-tech. The building in Lustenau, which I described before, is a very good example of this. There, the motto goes Atmosphere instead of machine. Personal details Prof. Dr-Ing. Werner Lang studied architecture at the Technical University (TU) of Munich followed by a Fullbright scholarship at the University of California at Los Angeles. After finishing his Doctorate Degree and gaining several years of practical experience working as an architect, Lang became an associate professor at the University of Texas in Austin and has, since 2010, been a professor of energy-efficient planning and building at the TU of Munich. Energy-efficient and economical The combination of ecological, economical and sustainable aspects is also on BayWa s agenda in the Building Materials Segment: A good example is the construction project Energy-Efficient Plus Housing Scheme which is currently being built

5 near Augsburg, Germany. The houses there generate more energy than they consume. This concept was developed with high efficiency and inhabitant health in mind. More information: BayWa r.e. renewable energy also completed the construction of a plus energy solar house in Tübingen, Germany in This building is supplied with electrical current, warm water and heat energy by photovoltaics. More information: