Daylighting controls

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To your first question, I can only say that in Radiance the control type is disregarded and always uses the "continuous" control type. As to why you see no change in EnergyPlus when using control type continuous but do see a reduction in energy use when selecting the other two types, I'll have to do some more investigation or talk to some of the EnergyPlus users over here.

As to your second question, the simple answer is "it depends". Placing the daylight sensor in the center of a 6x8x3 meter space is to tell the lighting control system "wait until the daylight levels are high enough all the way back here, before dimming the lights". A space that deep, with a ceiling that low, will not see very much daylight back there very often, and so an energy analysis of daylighting's efficacy based on daylight illuminance at that point will likely show little to no savings -- not a fair fight. Indeed, what most designers do is zone their lights so that they can dim or switch the lights closer to the perimeter (which receive more daylight, more often) sooner than those in the core. EnergyPlus allows you to emulate this somewhat by placing multiple daylight sensors in the zone and setting each to control a percentage of the total lighting load. Currently the Radiance support in OpenStudio has no such analog, but we hope to change that.