From the outset of the design competition, it has been the ECB’s stated aim that its new premises should be 30% more energy efficient than stipulated by the Energieeinsparverordnung 2007 (German energy saving directive). To achieve this aim, all possibilities were explored and analysed, particularly with regard to the facades and technical systems. The resultant energy design has the following features.
The Grossmarkthalle itself has a roof area of around 10,000 sqm. A system will be installed for collecting rainwater, so that it can then be used to both irrigate the gardens when there is not enough rain and flush toilets in the Grossmarkthalle.
The waste heat generated by the computer centre will be fed back into a ceiling heating system in order to heat the offices. The new ECB premises will be connected to the highly energy-efficient combined heat and power system of the City of Frankfurt am Main.
The Grossmarkthalle’s surface areas, e.g. the roof and windows, will be insulated in order to create a thermal envelope between the outside and inside areas, such as the staff restaurant and meeting rooms. These areas will have their own microclimate, as they will be integrated into the market hall as a separate house-in-house system.
In addition to the central ventilation systems, motorised ventilation elements incorporated into the building facades will allow for the direct natural ventilation of the offices. As a result, the fresh air requirements per person may be provided without the use of mechanical ventilation, if the user so chooses. People will also have more of an idea of what is going on outside. A mock-up building was constructed in order to test the feasibility and functionality of the facade design. The results of these tests showed that the facade design would indeed be feasible and functional.
In order to prevent the buildings from absorbing too much heat from the sun, highly efficient sun screens/glare shields will be integrated into the facades.
Another way to save energy is to use natural daylight. The offices will be fitted with daylight sensors, so that the lights switch off automatically when there is sufficient daylight. In terms of the artificial lighting for the offices, as well as for the atrium and the market hall, there has been much research into ensuring that they are lit sufficiently and efficiently at all times of the day.
In order to further reduce the energy costs of the building, geothermal loops were incorporated into the pile foundations, which descend about 30 metres until they hit Frankfurt’s bedrock. These loops can be connected to the water circuit and the heating pumps in the heating centre in order to extract heat from the ground in winter and coolness from the ground in summer.
To minimise the number of technical systems and the amount of energy required, certain areas, such as the atrium or the open areas within the market hall, will not be air-conditioned. Instead, these areas will function as a climate buffer and transition zone between the outside and the inside.
On 4 January 2003 Directive 2002/91/EC of the European Parliament and of the Council of 16 December 2002 on the energy performance of buildings entered into force. The German Government implemented the laws, regulations and administrative provisions necessary to comply with this Directive on 1 October 2007. The New ECB Premises project is the first major construction project in Germany to meet the required standards.