Hi All,

In term of mandatory of ASHRAE 90.1, The lighting in the sidelighting must use photocontrols to change the general lighting level in the primary sidelighted area to reduce the electric lighting when there is an adequate contribution of daylight into the space. The controlled lighting shall have at leat one control step between 30% and 70%.

So let say, in primary sidelighted we using photocontrols to control lighting by step control with 2 circuits, each circuit control 50% percent luminaires, photocontrols control lighting with 3 scenarios:

- Scenario 01: if the daylighting provides adequate illuminance, the lighting will be turn-off in two circuits, mean all luminaires will be turn-off.

- Scenario 02: if the daylighting provides 50% or more illuminance, the circuit 01 will be turn-on and the circuit 02 will be turn-off, mean 50% luminaires will be turn-off, and the zone will be sufficient illuminance.

- Scenario 03: if the daylighting provides below 50% illuminance, all circuit 01 and circuit 02 will be turn-on to provide sufficient illuminance to zone.

So my question here is that schematic design compliance with ASHRAE 90.1 in term pursuit LEED, or what strategies will be compliant with lower cost.

Thank you very much!