We’re working on a two stories building that is seeking LEED NC v3 certification. This building considers two vegetal strategies on its design.
1. The first one is a deciduous vineclimb shading device, 4,5 ft (1,5 m) far behind from the curtainwall facade. It will provide shadow on these facades depending on the foliage level throw the year. Regarding the modeling simulation of shading devices, ASHRAE 90.1-2007 Performance Rating Method, specifies:
d. Manual fenestration shading devices such as blinds or shades shall not be modeled. Automatically controlled fenestration shades or blinds may be modeled. Permanent shading devices such as fins, overhangs, and light shelves may be modeled.
We propose to model this automatic shading strategy as an vertical element, with appropriate properties of radiation and light transfer, according to the annual performance of the plant foliage.
2. The second strategy consists on a vegetal exterior wall layer. We pretend to model this layer, using E+ vegetation model, as if it were a traditional greenroof. Another alternative to model this strategy is using an extra layer with an equivalent albedo (0,7-0,85), so that it homologates the effect of the plant system.
We seek guidance to create models that are suitable which can give credits on Proposed Building Performance of ASHRAE 90.1-2007 Performance Rating Method. Specifically we ask:
- Is the vertical shading element model proposed before (1) suitable for modeling a vine climb shading dispositive?
- Are the Energyplus vegetation and equivalent albedo models adequate for the simulation of vegetation layer on walls (living wall, green wall)?. And if so, which of them is it preferred to use?
You rely on LEEDuser. Can we rely on you?
LEEDuser is supported by our premium members, not by advertisers.
Go premium for
Esteban Martinez
LEED ConsultantGreen Loop
11 thumbs up
January 14, 2011 - 12:10 pm
We have almost the same problem in a model we are putting toghether. The difference is that we have a decidius vineclimb shading device on the outside of the building, but we are not sure how to model the shading performance of the proposed element.
Did you found anything regarding this issue?
Tristan Roberts
RepresentativeVermont House of Representatives
LEEDuser Expert
11474 thumbs up
January 20, 2011 - 11:07 pm
I think this is going to be tricky, taking something with so much natural variation, and about which there is very little data, and trying to make the computer model understand it. Also, how are we do know how the vines will do over the years—will they be fully functional when the building is built, in 5 years, 10 years? I might consider not modeling this strategy.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
January 21, 2011 - 10:03 am
In our opinion you will need to base the assumptions in the model on imperical data from a study rather than your best estimates. If the product manufacturer has data that you can use that would work but the LEED reviewer will likely want to see what your assumptions were based upon. As such you should model these under the Exceptional Calcualtion Method.
You ask some difficult questions. Rather than ask them here I would suggest, if you have not done so already, that you post them on the Bldg-Sim - http://onebuilding.org/ - and Energy+ - http://apps1.eere.energy.gov/buildings/energyplus/energyplus_support.cfm discussion groups.