Testing the use of daylight-linked control systems to address integrative lighting and energy savings in office buildings

• DLCS’s ability in meeting visual and circadian needs and energy savings is assessed. • Two DLCS’s calibration strategies (S1 and S2) and four daily CCT profiles are tested. • DLCS is set to maintain constant work plane illuminance in S1 and melEDI in S2. • With poor daylight, S1 provides melEDI = 250 lx for high CCT and task illuminance values. • Using S2, the work plane illuminance values depend on electric light CCT profile. Daylight-linked control systems (DLCSs) are used to maintain constant work plane illuminance and save energy. If properly calibrated, they could be used to guarantee circadian requirements fulfilment as well. In this study, the functioning of a closed-loop proportional dimming system is simulated based on on-field measurements. Simulations are performed calibrating the system to achieve different targets: three work plane task illuminances (300 lx, 500 lx, 750 lx) and one melanopic equivalent daylight illuminance (melEDI) value (250 lx) alternatively. Four electric light CCT profiles (stable at 3000 K, 4000 K, and 6500 K, and variable during the day) are considered. Results demonstrate that when the system is calibrated according to work plane illuminance, melEDI values are always fulfilled under clear sky and with overcast sky when task illuminance and CCT are high. When the system is calibrated to meet circadian requirements, the CCT choice is crucial to guarantee work plane illuminance.