The project aims to overcome uncertainties in predicting energy consumption of HVAC (Heating, Ventilation and Air-Conditioning) and lighting services in open plan offices by developing an integrated approach to study the cause-effect relationship between occupants and combined indoor environmental factors (thermal, visual, air quality and noise). The impulse behind the dynamic and multivariable behavior of occupants will be identified through the field study with the implementation of point-in-time mobile questionnaires coupled with IEQ measurements