Corresponding author: Ir. Michiel Ritzen, Eindhoven University of Technology/Zuyd University of Applied Sciences, The Netherlands. E-mail: m.j.ritzen@tue.nl Environmental, commercial and societal developments in the Netherlands stimulate the environmental improvement of the existing office building stock. In the Netherlands, about 15% of all office area was vacant in 2012, and the majority of offices have a relative poor energy performance. To measure the improvement, different assessment tools are applied. These tools either focus on one aspect, such as operational energy, and result in a specific outcome such as MJ/m2 , or these tools combine different aspects, such as energy and materials, through a weighted system and result in a generic outcome, such as ‘excellent’. In this research, the relation between assessment outcome and actual environmental impact is investigated of both types of tools, by reflecting the outcome of the tool to the carrying capacity of a system. The relation is investigated through a comparison of the energy and material aspect of three office façade renovation solutions using four different assessment tools. Using a tool in which energy and material impact is related to the carrying capacity, current energy focused optimization might lead to a sub optimization of actual environmental impact. To illustrate this, a calculated façade solution is presented with minimal environmental impact based on carrying capacity.