One of the first commercial Plus-Energy buildings in Germany (4,3 MB, PDF-Datei)
 
Constance. Since 8th July, Stadtwerke Konstanz [Constance Public Utilities] has been advising its customers on all current questions concerning the topics of energy, mobility and leisure time in a new building. During the construction and operation of the building, the Constance  company has relied on sustainable technology: The Energy Cube is one of the first Plus-Energy buildings in Germany that is used commercially.
 
Background of the investment
The large building project cost the company around three million Euros. The two managing directors, Kuno Werner and Konrad Frommer, are unanimous about the purpose of the investment: “Our company has grown in the past decade and our business has changed drastically through competition and technical advances. It has also become much more concentrated on consultation. In the new building, we combine all our competencies to benefit our customers. The Energy Cube is an external signal of a new era in customer service by Stadtwerke.” 
 
Aesthetic and clear – the architecture
In addition to the administration building at Max-Stromeyer-Straße, there is now a four-storey building with a clear cube design. Its edge length is 15 meters. The Energy Cube has a total area of approx. 800 m2 on all floors. The building rests on 47 piles that had to be pushed up to 18 meters deep into the ground. The façade is transparent and appears very aesthetic with its scattered opaque surfaces. It consists of 80 large glass panels with a total area of 1000 m2. "In the inside of the Energy Cube, transparency has been maintained - not only for light, but also to demonstrate our openness to customers," said Arnold Wild, architect and construction manager of Stadtwerke Konstanz. Individual areas of the façade can be illuminated in the company’s colours.

Innovative and sustainable – the energy concept
In planning the new customer service centre, special emphasis has been placed on energy efficiency and the use of renewable energy sources. The new building will generate more energy than it consumes over its useful life. The energy of the sun and earth will provide power, heating and cooling. The chosen shape was a cube because it is the most energetically optimal geometric shape for a building. Reversible pumps obtain heating and cooling from the earth. These are used in a water cycle that runs through all the ceilings in the building which are set as needed for the right temperature control of the building. A five and a half meter long skylight can be opened for ventilation and cooling. On the roof and on the south façade, a photovoltaic system generates electricity. A very innovative concept was developed for the façade. It will bring in as much natural light as possible at all times while using as little electric light as possible. As a Plus-Energy building, the Energy Cube will not only produce energy but also consume very little energy. If necessary, the façade has the task of capturing the sun's energy for heat generation. In the summer, however, the sunlight will be blocked out as much as possible to obtain a comfortable room temperature. To meet these numerous functions, Stadtwerke developed a special functional glazing in cooperation with an engineering firm for energy technology and the University of Rosenheim. It consists of a transparent outer shell and triple glazing, solar control and light control lamellae and an additional, internally applied single glazing. The circulating air in the spacing is sucked in and distributed as needed in the building using a heat exchanger.
 
Descriptive and versatile – the consultation
Changing exhibitions and seminars on the company’s areas of expertise will complement the company's wide assortment of products. In the Energy Cube, advice on the environmentally-friendly and economical use of energy is combined with the commercialisation of sustainable energy systems and their application in mobility. The new customer service centre is open for advising private and commercial customers as well as for conversations with civil groups active in politics and economics from Constance and the surrounding region. In the energy cube, Stadtwerke also provides presentation space as well as training on new subjects such as fibre optics and smart meters for skilled craftsmen from Constance. "In this way, we want to improve the cooperation between the city and local professionals even further," states managing director Werner Kuno.

Life in the Energy Cube – a tour
On the ground floor, visitors are greeted at a large information desk by the customer service staff. In the large room there are also advising areas and information columns. On the first floor, sales employees provide advice to customers on all aspects of gas, electricity and water supply. In the multi-functional showroom on the second floor, demonstration objects will support the customer service. In addition to classical energy consulting, the customer will also get insights into the newer technologies for energy use. For example, he/she can examine an intelligent electricity meter or directly compare data transfer rates of copper and fibre optic cables. Complicated technical issues will thus be made tangible. The seminar room is located on the top floor. With a great view in the direction of Münster and Säntis, up to a hundred people can attend lectures or seminars. The large room can be divided by a glass wall. There are various events planned - from information about current projects in redevelopment areas to the panel discussion on future issues such as the networking of mobility and energy concepts in urban renewal. And group workspaces for the joint development of solutions with customers are also planned in the building concept. 
 

 
 
Data Energy Cube
 
  
Area / total area:  225 m2 / 800 m2 
 
Roofed space:      3,500 m3 
  
Floors:        4
 
Main dimensions:  Edge length: 15 meters (Exact cubic shape)  
 
Construction:  Massive building with pile foundation and energy façade, free-standing 
 
Energy concept:  Energy Plus building with geothermal energy, photovoltaic energy, energy façade, thermally active concrete core and heat pump with heat recovery 
 
Use:          Customer service centre
 
Commissioning:      July 2011
 
Costs:         approx. 3 million Euros net
 
Data Façade Energy Cube 

Total size:        approx. 1000 m²
 
Large photovoltaic modules:         3 x 4 m
 
Weight of each panel:    1.014 kg 
 
Area of solar façade:    230 m² 
 
Max. energy generation façade:   approx. 23 kWp
 
Total energy transmission 
 
Transparent  fields g tot:   0.13 % 
Insulation value opaque fields, u value: 0.11 W/m²K