I am using Ecotect to explore the best design schemes for an office building taking place on the 8th, 9th & 10th floors on top a 7 story parking garage. We are using a fair amount of windows and some skylights and have the need to identify/avoid glare. I am currently calculating Natural Light Levels, Radiance Interior Luminance Renderings and Optimal Shading Design.
So far... I am getting the following results: 8th 12.34% = 61.7 fc -or more-, 9th 8.48% = 42.4 fc, 10th 7.37% = 36.85 fc. We are very concerned about the amount of light on the 8th floor and I am trying to identify tools that could inform where to best change the design so we could achieve ideal interior luminance.
I am thinking about modifing skylight size and adding more shades and to run Natural Light Levels as well as Radiance Interior Renderings until finding the ideal interior lighting level.
Do you have any other ideas/suggestions?
Maybe I also should check on reflectance values. Ecotect is setting a reflectance value of .90/.93 for my ceilings, .75 in floors, and in my walls .90 Internal and .68 external.
Could I use general reflectance values...
walls = 70% ceiling = 90% floor = 30%?
Maybe I also can run daylight factor on Radiance and/or Daysim?
I much appreciate your suggestions,
Judith
Reflectance
Hi Judith,
Yes, it sounds your space is receiving a lot of light.
But also, I have noticed your high reflectance values - and I don't like them
I think your ceiling are too bright. Try to keep your ceiling reflectivity between 70 and 80%. Your wall can stay in the 40-80% range, and your floor are just fine, between 20 and 40%.
You should see a good drop in internal daylight once you lower down your reflecive value a bit. Note that the visual colors you get in Ecotect while adjusting these values may not look right, but analytically, it should be.
Also, YES, I would definatelly use Radiance for the interiro daylighting, as it will be able to account for multiple reflections, better than Ecotect. And I know YOU know how to use RADIANCE...I've seen you do it.
Let me know if you get better results.
Olivier
Radiance False Colour
Thanks Olivier,
I have been try to conver my Radiance Rendering into False Colour, I am getting a window that says "RGBE read error". Do you know anything about this?
-judith
RGBE error
Hi Judith,
RGBE is the image file format used by Radiance.
For some reasons, your computer doesn't seem to like it. Does it happen every time you try to convert from your Radiance image into false color? I do not know how to solve this problem
Could it be a memory issue? Try turning off other programs running in the background to see if that makes a difference.
Let me know.
Olivier
Void Properties
Hi,
I would like to make sure that the properties of the voids in my model are correct. Ecotect Voids properties are set up(by default)as follows:
U Value:.98943
Admittance: 1.76118
Solar Absorption: 1
Transparency: 1
Thermal Decrement: 1
Thermal Log: 0
SBEM CM 1 & 2: 0
Thickness:0
Weight: 0
Internal and External Reflectance: .98
Emmissivity (Internal and External): .86
Specularity: .13
I would guess that everything needs to be 'cero' because is a surface that defines 'nothing'... Uhmmm, or do we need to mimic the values/density of the air/space around?
-judith
Void Properties
Hi Judith,
uhmmm...I would not edit these default values, but if you feel they should be otherwise...
Remember that Ecotect is good for comparative studies, so while i understand you are looking for accuracy, I believe that here, consistency would be more important than accuracy.
I do have similar values on my version of Ecotect. A bit funny that there is a 13% specularity uh?
Olivier
Glare Values
Greetings,
I am exporting from Ecotect to Radiance to study glare. I am producing false color renderings of my model knowing that they will inform me about light contrast within that space. Once I get the false color image, I calculate the light contrast ratio by dividing the highest color number on that image by the lowest. I am getting a variety of light contrast ratios… from 0 to 15. I am trying to figure out which ratio numbers are indicating a comfortable amount of light contrast and which numbers indicate glare. I am not finding a consistent answer.
Which numbers do you think are indicating glare?
-judith
Light Contrast Glare
Hello Judith,
From my litterature Concepts and Practice of Architectural Daylighting by Fuller Moore, the following contrast limit to comfort are listed:
3 to 1 Between task and adjacent surroundings.
10 to 1 Between task and more remote darker surfaces.
1/10 to 1 Between task and more remote lighter surfaces.
20 to 1 Between fenestration and adjacent surfaces.
40 to 1 Anywhere in the field of view.
I hope that helps
Best,
Olivier