I understand that daylight simulation models are to use sky conditions on either March 21 or September 21. If we choose Option 3: Measurement, must we measaure on March 21 or September 21? I have not seen this listed as a criteria for measurement. Has anyone else?
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TODD REED
Energy Program SpecialistPA DMVA
LEEDuser Expert
890 thumbs up
December 9, 2010 - 8:22 am
The 2.2 Reference Guide lays out the guidelines for actual measurements. The protocol for taking measurements is outlined in the LEED-NC v2.2 Reference Guide which states that measurements must be taken on a 10-foot floor grid for all occupied spaces and must be recorded on building floor plans. Per the daylight modeling protocol, measurements should be taken 30” off the floor, under clear sky conditions at noon. Please document the time of year the measurements were taken. Calculations should be taken at solar noon. This is the time of day that divides the daylight hours in half (between sunrise and sunset). Using this definition, daylight savings does not need to be taken into account. Since all measurements can't possibly be made all at once right at noon, take them within a reasonable timeframe before and after noon (i.e. between one hour before noon and one hour after noon) and do not take measurements in direct sunlight. Records of indoor light measurement must demonstrate a minimum daylight illumination level of 25 footcandles.