Workplace change and New Ways of Working (NWoW) seem to have become a fixed value in FM practice in the Netherlands today. Stimulated by new technological possibilities and maybe even by the world-wide crisis, companies are rethinking their office environments. The possibility to work anytime and anywhere seems key. However this requires a different approach to quantify the needed space and determine the types of workplaces to fit an organisations’ processes. Since one employee is no longer automatically linked to one (specific) desk, and employees are expected to choose an appropriate workplace depending on the task at hand, the calculation of the needed floor space has become more complex. The expected attendance (presence in the office) needs to be quantified to give an indication of how much ‘desk space’ needs to be facilitated. However one also needs to take the activities that employees perform into account, to be able to specify different types of workplaces that can accommodate them. For this purpose a new calculation model was created. The PACT (Places and ACTivities) calculation model allows us to gain insight in the number and type of spaces needed, modulated by different scenarios and fitting to the organisation and its work processes. Additionally calculations can be limited to an existing framework (e.g.: the dimensions of the current building) as calculating a completely ‘hypothetical’ building often has little value. New variables in the model allow for calculations to be limited by dimension and time constraints. Different scenarios help to discover which space requirements fit the ambitions and work processes of the organisation best. Through manipulation of different variables in PACT, valuable insight can be obtained into the number of work spaces (of specific types) needed. Moreover they allow us to consciously consider an ‘allowed level of margin’ while determining the dimensions of a work space (where the possibility of providing too many work places and the possibility of providing too little places is optimal).