The Institute for buildings and energy was commissioned, to evaluate the energy efficiency of design concepts of the architecture competition for the headquarter of energy supplier STEWEAG-STEG GmbH in Graz. Within the framework of a restructuring, the client decided to refurbish a 1960s high rise building at Leonhardgürtel and expand the location by another 150 work stations. As a result of the consultancy, the STEWEAG-STEG GmbH was able to assess a number of different designs with respect to their energy efficiency and comfort. Amongst others, the assessment of the designs included the impact of the position and orientation on the site, the impact of the building form on the energy balance, the optimal design of the fassade as well as addressing the question as to what extend natural ventilation is possible.
Apart from the assessment of energetic aspects of the submitted design proposals as part of the framework of the architecture competition, different alternative strategies for the refurbishment of the office building were evaluated as well. The breakdown of the energy demand and their individual causes yields many surprising causes for most clients as well as planners. This knowledge, however, is precondition, to reasonably assess the relevance of individual aspects. It was particularly noted that most of the planning teams efforts focused on energetic improvements in terms of reducing heat losses during the winter period by means of upgrading the insulation standards. However, results of dynamic computer simulations showed, that an additional insulation of the opaque wall surfaces only have a minor impact towards the overall energy demand and considering the tight budget for the project, strategies should to be looked for to achieve the highest potential benefit with the same effort.