Hello,
for our CS project we would like to implement option 2. The difficulty I have is that the building was constructed in the early 90ties and only little information on the existing parts is available. Unfortunately I have no proven VLT for the calculations. In addition windows literally run all around the house on every storey, but they all do have blinds on the outside, which can be operated individually.
Would it still be possible to achieve the ICQc 8.1 via option 2 or would we be forced to measure the whole building?
Thanks.
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David Posada
Integrated Design & LEED SpecialistSERA Architects
LEEDuser Expert
1976 thumbs up
October 10, 2011 - 3:38 pm
You will need a reliable source for the VLT value in order to use option 2. It might take some time, but if you can research any of the drawings, specifications, permits, payment receipts, or paperwork from the original construction that could help. If you can determine the manufacturer of the windows, they may have a record of the installation or product data from that time.
TODD REED
Energy Program SpecialistPA DMVA
LEEDuser Expert
890 thumbs up
October 12, 2011 - 10:32 am
Use a good light meter. Take a reading on the inside of the window, about a foot away. Then immediately take a reading outside the window. Simple math will give you the VLT. It is not as scientific as the NFRC method, but it is close enough to get you what you need for the calcs.
Do not take readings of direct sun. Take readings at windows where there is just clear sky. Be careful of reflectances from surrounding objects and the glass itself. Turn off the interior lights.
Nicole Isk
Senior ConsultantES EnviroSustain GmbH
22 thumbs up
October 13, 2011 - 4:04 am
I did not know that that would be sufficient.
Thanks a lot!
TODD REED
Energy Program SpecialistPA DMVA
LEEDuser Expert
890 thumbs up
October 14, 2011 - 9:09 am
The other option which is also acceptable for EAc 1 is to use table A8.2 in ASHRAE. This gives a VLT and other properties to use if it is unknown. Not the best properties, but it is a referenced standard and accepted method.
Valerie Molinski
Environmental Stewardship ManagerTarkett North America
102 thumbs up
February 6, 2012 - 10:09 am
My project is in a high rise, built in the early 90's, so I cannot take a reading outside. I wonder what kind of success people have had using the default VLT's in the ASHRAE table.