A common approach in office refurbishment is to employ mixed mode strategies for managing the internal environment. Here, mechanical and natural ventilation is used by exploiting opening windows and more advanced systems such as nighttime purging, stack-effect ventilation via chimneys or atria, and mechanical ventilation with heat recovery (MVHR). Although the passive approach is preferred by facilities managers, users like to have active systems that allow a degree of intervention. Hence, in office refurbish ment opportunities should be provided for active adaptive behaviour to support enhanced comfort or perception of com fort even if there are short-term energy disadvantages. The basis for this argument is not based on carbon emissions but on productivity. A positive workforce able to adjust the condi tions in the workplace is likely also to be productive and com mitted to the task in hand. The problem with solely passive systems is that they may bring about energy efficiency, but they can alienate those working in the office by denying any ability to moderate environmental conditions. This applies to ventila tion (and hence cooling) but also to the

control of draughts. It is equally true of heating, lighting levels and solar shading.