I have several projects where the fenestration VLT assembly is unknown or unlabeled. These projects are renovations where the exterior envelope was not changed. Would GBCI accept VLT assembly values from ASHRAE 90.1-2007 Appendix A, table 8.1 and 8.2? This table is generally used for energy models when the fenestration assembly is unknown or unlabeled. The following are some values from table 8.2: Clear single glazed vertical fenestration=0.76 Clear metal double glazed vertical fenestration=0.66 Tinted metal double glazed vertical fenestration=0.40 Thanks.

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TODD REED

Energy Program Specialist

PA DMVA

LEEDuser Expert

626 thumbs up

Mon, 09/12/2011 - 17:04

Take a light meter, take a measurement in the inside of the window and on the outside. The ratio would be as close as you can get to the VLT and may be better accepted since it is actual measurements. But i would say that you can use the ASHRAE tables because in EAc 1 when the glazing is unknown you can use the tables. I would find the method acceptable. But say measurement would be more accurate.

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FAQs about IEQc8.1 :

Unlabeled fenestration visible light transmission(VLT)

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