This paper highlights the integration of the dynamic daylight simulation software DAYSIM [1] into the transient simulation software TRNSYS [2] in order to predict the energy reduction due to the availability of daylighting and lighting control strategies. The simulation of two different envelope configurations (traditional wall with 40% of glazed area versus a fully glazed curtain wall) fitted in an office room is performed on the basis of real weather data (London). The energy consumption and carbon dioxide emissions of both envelope systems are calculated for various lighting control strategies.