How accurate would Ecotect's daylighting engine be if we were trying to calculate the Daylight Illumination for LEED compliance. LEED requires calculation at a particular time/date/month and on 'clear sky' conditions. I maybe wrong on this but looks like ECOTECT's daylighting engine does not take these parameters, particularly clear sky conditions, into account.
I would appreciate input from the developer's also.
Also if anyone has experience for modeling daylighting simulations for LEED compliance using ECOTECT, any input would be appreciated.
I would also like to get any input if DAYSIM is a better option for doing this type of analysis but using ECOTECT as the front end.
not a true DF
>> Daylight Factors for LEED compliance. LEED
>> requires calculation at a particular
>> time/date/month and on clear sky conditions
If this is what LEED requires (and I wouldn't really know as I am not a LEED expert by any means) then this is not a strict "Daylight Factor".
ECOTECT sticks to the specific definition and specification as per the BRE publications and as such uses the Split Flux method -- there is information on this in the wiki (squ1.org) if you want to have a read as to the full details of the method.
As a general summary, a true DF calc is done using overcast sky conditions as a "worst case" scenario. The theory being that if you meet certain minimum levels in your design with a worst case sky condition then obviously you will meet these and some when there is a clear sky.
As this is the only algorithm used internally in ECOTECT for lighting it wont allow you to specify these conditions/time specs etc. so I would suggest you get ECOTECT to run the calc with the Radiance engine instead.
Please search before posting a question.
Correction: Daylight Illuminanation and LEED
Thanks for the guidance.
I looked into the reference manual for LEED to confirm if it was daylight factor that LEED was asking for or not. It is not the daylight factor, but daylight illumination for the spaces where daylighting simulation has to be followed.
LEED reference manual states that you calculate the daylight illumination for each applicable space using the following daylight criteria: clear sky conditions at 12:00 noon on the equinox (Mar 12/Sept 21) for the projects specific location.
ECOTECT only allows two options 'CIE Overcast Sky' and 'CIE Uniform Sky', so based on your comments and no option for 'CIE Clear Sky', I would need to export the model and run it with the Radiance engine.
>> I would need to export
>> I would need to export the model and run it
>> with the Radiance engine
Not so much "export", but rather get ECOTECT to run Radiance for you is how I like to think of it
Please search before posting a question.
Daylight Illuminanation and LEED
CTG,
I was wondering what version of LEED you are referencing when you are quoting the LEED manual? The guide we currently use doesn't contain such specifics.
Also, from what I can figure out, radiance doesn't allow you to define the type of sky used for DF calcs. Rather a specific DF sky is used to generate the output.
We are noticing the DFs given by radiance correspond to the hand/spreadsheet calculations typically submitted for this LEED credit whereas the Ecotect DF returns contradictory results.
USGBC LEED-NC 2.2 page 383
USGBC LEED-NC 2.2 page 383 sets forth the criteria for the software to use.
CaGBC LEED-NC 1.1 contains no such specifics, which may be a benefit, or a problem, depending on your approach.
I would like to hear from anybody who has had some success using ECOTECT and/or Radiance to meet the LEED EQc8 requirements.
Daylight Factor and LEED
Hello,
I would recommend the use of DAYSIM for the LEED NC credit 8 calculations.
Daysim not only gives all the resulting values for each node of the analysis grid in its report, but also highlights those that are above the 2% threshold, as well as gives a report line stating whether or not the analysis would pass the LEED credit or not.
Anyone using Daysim for LEED credit?
Olivier
It does not have to be only DF
As it is indicated here DF is not given as the only EQ8.1 option. Therefore any analysis that can produce the following can be regarded as the appropriate.
OPTION 2 — SIMULATION
Demonstrate, through computer simulation, that a minimum daylight illumination level of 25 footcandles has
been achieved in a minimum of 75% of all regularly occupied areas. Modeling must demonstrate
Radiance and Illuminance level
Hello,
I am also attempting to use Radiance to export the analysis grid and bring it back to Ecotect in order to determine if the illuminance levels are acceptable by LEED-Canada 1.0 standards.
The calculations seem to be going well, however, once check off the visible nodes option, there seems to be some light levels within closed rooms, devoid of windows. Would this be a bug of the program or is there something that I misunderstood?? After all, if there is no way for the light to penetrate the closed space, it should have 0 lux as illuminance level.
Oliver, I will try to use Daysim for the calculations as well and see what it gives me...
However, if anyone has a solution to the problem or has encountered a similar situation, please let me know.
Anna
"LIGHT LEAKAGE IN CLOSED ROOM"
Hi Anna, did you make a model in ecotect or import the model from CAD? I usually model in ecotect to avoid that problem.
You just ignore the number if it is too small and it's not substantial (1-2 lux <-- in real world, human eyes will not recognize the difference). If the number is quite high, I usually redraw the model in Ecotect.
I used to use lumen designer and it was happened in there as well and even worse (5-10 fc or 50-100 lux in closed room).
For LEED in US, you could follow the guide in the reference. I use Ecotect+Radiance for some LEED project, and it's pretty straight forward.
maybe someone who knows the algorithm behind the engine could explain about light leakage in closed room.
CMIIW
Tranparent walls
Hi,
I have the same problem than Anna, and I did make the model in Ecotect. The only thing that I imported was a DXF plan from Autocad. Could it be the reason? In fact my walls are pretty much transluscent when I use the Radiance plug-in, but they are not in Ecotect.
If you have any idea why this is happening, please let me know.
Anik
light leakage and funny factors
I also see light leakage into closed rooms using a model built in ecotect. I have also noticed none of the DL factor %s drop below 1.
Light Leakage
Just adding to this by mentioning that, while keeping the same model, using DAYSIM for the analysis seems to eliminate the leakage problem.
Light Leakage
Hi prairiesmith,
I am not sure what happened with your model. But DF should be really low althought the numbers are not zero.
My model usually give 0.01%DF if there is no windows.