Project Summary
The building of the Bremen state and university library has been in operation since 1975. The building has deep plan floor spaces and is fully air conditioned. The primary energy consumption of 820 kWh/m²a is high when compared to similar new buildings. The university is supplied with district heating from a waste incineration plant. Because new consumers have been connected to the grid the maximum capacity of the plant has been reached. Therefore it was decided to retrofit the university library, one of the main consumers of energy on the campus.
The main goals of retrofitting were to reduce the energy consumption by more than 50% and to improve indoor climate and user acceptance. A monitoring program of energy use and indoor climate before and after refurbishment served to optimise the planning process and to control the efficiency of the refurbishment.

Retrofit features
The retrofit includes measures to the building envelope as well as the internal systems. Originally heating and cooling was provided exclusively by supply air. The new HVAC system separates the heating and cooling. The air change rate varies according to the requirements of indoor air quality. Perimeter offices have been equipped with operable windows to allow natural ventilation. All facades have been equipped with new glazing. New repositioned luminaires have been installed in the library. Daylight responsive controls have been installed in daylit zones. Some book storage areas have been converted to open access areas.