Hi there,
I am currently calculating the power allowance for exterior lighting in a school project.
In this case, there is quite a lot of exterior spaces and landscaping. Almost one-third of the trees are illuminated, however, I am not sure which could be an acceptable and effective way to measure the illuminated area for the LPD allowance calculation.
As per now I have considered "approximately" the area that will "feel" illuminated. That is about 3m around the trees lighting. I could not find any example nor information about how to perform this calculation.
Have you addressed this issue before successfully? Is it ok to calculate approximately? do you have a method or a recommendation on how to do this calculation?
Thanks
Neeraj Sharma
Sustainability ManagerConserve Solutions- Riyadh, Kingdom of Saudi Arabia
1 thumbs up
April 25, 2023 - 7:47 am
What you are doing is okay. Simulations work on a baseline, so whatever are you select provide a narrative and the baseline should match the same area, and you are good to go.
Julio Fernandez Amodia
5 thumbs up
April 25, 2023 - 10:13 am
Hi Neeraj,
I am confuse. There is no baseline for exterior lighting, as far as I know it is the same LPD as the proposed.
My question was regarding the mandatory provisions from ASHRAE 90.1 - 9.4 and how to measure the illuminated landscape areas.
Thanks
Cory Duggin
Senior Energy WizardTLC Engineering Solutions
53 thumbs up
April 25, 2023 - 10:17 am
I have used the aproximate area around the tree that is lit based on the photometrics.
Neeraj Sharma
Sustainability ManagerConserve Solutions- Riyadh, Kingdom of Saudi Arabia
1 thumbs up
April 30, 2023 - 7:03 am
There is no specific mandatory requirements for exterior however ASHRAE 90.1.2010 only mentions to meet the requirements of table 9.4.3 A & B. If you want to claim savings on exterior lighting, you can but only for tradablesurfaces, non tradable it needs to be same in both the proposed as well as baseline cases. Usually LEED doesn't comment on astonomical switch provided for exterior lighting until the modeler is not claiming savings because of the use of lighting controls .
Julio Fernandez Amodia
5 thumbs up
April 30, 2023 - 7:39 am
Hi Neeraj,
The mandatory provisions apply mainly to lighting controls and exterior lighting power densities, including landscape.
Maybe i have misunderstood something.
Neeraj Sharma
Sustainability ManagerConserve Solutions- Riyadh, Kingdom of Saudi Arabia
1 thumbs up
May 2, 2023 - 2:34 am
Just work on the Lighting Power densities, consider savings on tradable surfaces. Skip the control part. LEED doesn't raise a question on it, also all the buildings usually provides an astronomical switch, which is the major requirement. Refer to the Minimum Energy performance calculator lighting tab, you will understand what is required.