The energy concept for new head office of the Heinrich Böll Foundation in Berlin puts the building in the ecological vanguard. Highly innovative technology in small doses creates a pleasant working environment in the modern office spaces. It boasts an energy consumption of only 55.7 kWh/m2 , which undercuts the legal maximum by half. This makes the building a leader in the field of modern office and conference centre design. Close co-operation between the client, the architect and the building services engineers ensured that innovative solutions were successfully implemented within a tight budget.
Sustainability is one of the core values of the Heinrich Böll Foundation. Sustainability was also the guiding principle of the energy concept, which was developed for the foundation by the Swiss engineering firm Basler & Hofmann, from Zurich. The concept follows three basic principles:
- Intelligent systems with as little equipment as possible. This saves resources and keeps down the installation and operating costs.
- Energy is not lost until it leaves the building. Waste heat is recycled in an innovative manner.
- Ventilation and cooling are as natural as possible and give users maximum control. In many office buildings, the occupants are left to the mercy of the technology. At the new head office of the Heinrich Böll Foundation, the staff can decide the degree of ventilation and cooling for themselves.
In partnership with Grammer Solar, a photovoltaic system has been installed on the roof. This has an annual energy yield of some 53,000 kWh and feeds into the district heating system.
Factor of 10 – Cooling with a Clear Conscience
Modern office buildings suffer from an inherent paradox: they are well insulated and therefore need less energy for heating, but instead they need more for cooling. The huge quantity of office equipment in use these days warms the building up from the inside and there are no longer any poorly insulated points in the envelope through which excess heat can escape. In many conventional office buildings, the air conditioning has to run at full capacity throughout the summer, guzzling energy. For the occupants, that means having to keep the windows closed.
Not so at the Heinrich Böll Foundation: Here it is water that is used for cooling, not machinery. Outlet slits run at cill level along the glazing in every office. The cill casing houses high-performance heat-exchangers, through which water at a temperature of 20° C circulates in summer. A small ventilator inside ensures that that cooled air is distributed throughout the room. Even when the temperature outside is over 30° C, the room temperature does not rise above 25° C.
The water for cooling comes from what is known as an adiabatic recooler (→definition), situated in the basement. This has cooling fins, onto which normal tap water is sprayed. The energy used when this evaporates is drawn out of the fins, reducing the temperature of the coolant water inside to 20° C. The cooled water is then ready to circulate through the under-cill heat exchangers once more.
The advantages of such a system are plain to see: conventional air-conditioning systems need water at a temperature of 8-10° C. That coolant is warmed up again in the rooms to a temperature of 12° to 18° C, which consumes an unnecessarily large quantity of energy. The system that is used in the Heinrich Böll Foundation does not need any such 'jump in temperature'. As a result, it cools ten times more efficiently than a conventional system would.
Winter Heating from the Servers – an Award-winning Idea
The under-cill installation that cools the offices in summer also heats them in winter – and it does so with the same high efficiency. Whereas conventional heating systems need hot water at temperatures of up to 50°C, the innovative under-cill installation functions with a flow temperature of 28° C. It also makes effective use of heat that elsewhere is just a nuisance to be disposed of: the heat produced by the computer network servers. The servers of the Heinrich Böll Foundation are kept in cool racks, which remove heat rather as a fridge does. This arrangement integrates the servers with the building services system and makes their heat directly available to it. Water flows into the cool racks at a temperature of 23° C, where it is warmed by the servers to around 30° C. It is then fed into the heating system and circulated through the offices to keep them comfortably warm in winter. The only 'cost' of this heat is the energy needed by the pumps to circulate the water – ninety percent can be used directly as heat energy. In summer, the servers too are cooled by the adiabatic recooler. For this extraordinary concept, devised by Basler & Hofmann, the Heinrich Böll Foundation has received the Green CIO Award. This award is given in recognition of innovative projects that significantly improve the energy efficiency of IT systems.
The Atrium as a Lung
In order to keep the CO2 content of the air inside the building down to a normal level, a regular inflow of fresh air is necessary. Many modern office buildings function only with costly ventilation systems. The Heinrich Böll Foundation, in contrast, has opted for a solution using natural ventilation. The atrium within the building works rather like a lung. In summer, the internal courtyard is aired naturally through the open roof of the atrium. In winter, when the roof is closed, a ventilation system coupled with heat exchangers maintains a flow of fresh air into the atrium. This extracts heat from the exhaust air and uses it to warm the fresh air being brought in. The office spaces and internal corridors can be opened up to the atrium, creating a cross current to provide the interiors with fresh air as needed. Thanks to the atrium, this occurs without the heat loss that would otherwise be experienced in winter. By exploiting the natural convection currents in the atrium, it is possible to achieve a maximum of comfort in the building with a minimum of energy consumption.
The Key to Success: Integrated Design
A modern office building is a complex system. Only when the architecture, the façade and the building services are closely coordinated can primary energy consumption* be reduced to a minimum. The energy balance of the new office building takes into account not only the energy consumed in daily operation, but also the energy needed to produce the technical systems and equipment.
If you have questions, please contact the following:
Energy concept, building performance, ecology, MEP planning
Basler & Hofmann
Ingenieure und Planer AG
Philipp Grob, Forchstrasse 395, CH-8032 Zürich, fon 0041 79 353 89 82
Heinrich Böll Foundation
Dr. Birgit Laubach, 030 285 34 111, e-mail: firstname.lastname@example.org
fon +49 9621 30857 12
* Primary energy refers to the energy content of energy carriers as they occur in the natural state (e.g. natural gas and oil).