With the exception of the ground floor (staff canteen, library, reception) the Forum Chriesbach is not heated. The warmth generated by people, work aids, lighting and solar radiation is sufficient to maintain a pleasant ambient temperature. The roof, floors and façades have excellent insulation; air is renewed continuously and controlled from a central unit. The temperature and air quality are only monitored in the comfort zone (work and conference rooms), but not in the atrium. Hence the optimum room climate is achieved when the doors are kept closed.
In winter the fresh air intake is preheated in the thermal register and warmed up again by the waste heat from the computer servers. In addition, the heat recovered from exhaust air is also utilised via heat exchangers. Where necessary, it is possible to heat up the intake air using the hot water tank. This tank is heated by solar panels, the waste heat from the refrigerators in the kitchen and (where necessary) from the heating network on the Campus Empa Eawag site.
In summer the intake air is cooled by the thermal register and distributed to the rooms. On hot days the building is cooled at night via the window casements which open automatically. The warm air escapes through the atrium roof and cool air flows into the rooms. The photovoltaic installation on the roof provides c. 100 MWh of electricity per annum, around one third of the operating energy (without servers) for the Forum Chriesbach. The solar thermal installation produces around the same amount of energy as is consumed via the site heating network, i.e. around 24-26 MWh per annum.
The detailed energy balance of Eawag's Forum Chriesbach has been investigated and documented in a scientific study.
| || Planning || Values '07 |
| Heating demand Qh (standard utilisation SIA) || 14 || kWh / m² BEI a || 24 || kWh / m² BEI a |
| Thermal consumption from Empa-Eawag's on-site heating network || 24 || MWh / a || 67 || MWh / a |
| Utilisation of waste heat and commercial cold || 7 || MWh / a || 16 || MWh / a |
| Output of vacuum tube collectors (50 m²) || 24 || MWh / a || 26 || MWh / a |
| Electricity consumption of servers || 219 || MWh / a * || 129 || MWh / a ** |
| Electricity consumption without servers || 121 || MWh / a || 195 || MWh / a |
| Electricity generated by the photovoltaic installation (459 m², 77 kWp) || 60 || MWh / a || 71 || MWh / a |
| Total grey energy |
| 12000 || MWh |
| Grey energy (average service life 37.6 a) |
| 19 || MWh / a |
* Planning for server performance: 25 kW
**Server performance 2007: 16 kW (2009: 20 kW)