[Radiance-general] Glare and visual confort indices -- Are they ready?

[Christopher Rush]

I’m not well-versed enough to give an opinion on which are ready for use in any particular application, but I would give *my* opinion on your closing thoughts. If the calculation method for the metric isn’t changing, but maybe there’s ongoing research into appropriate values and applications, maybe the metric is useful enough to help “guide the design in the right direction.” However there may be some metrics that have gone out of favor or been invalidated by current research that could be excluded – to avoid a curious user applying something they shouldn’t. But sometimes even the outdated metrics may still be referenced in some governing design standard and a user may need it for a particular project.

As with any other metric, the designer has to know the correct application and the appropriate target values, or which magnitude of difference between two designs might be considered negligible. Something as simple as illuminance isn’t changing in principle, but the design standards and recommended values are still changing and being clarified or fine-tuned. And a designer has to know the appropriate application where daylight factor, or daylight autonomy is an appropriate metric. So if a particular metric is in question and has ongoing research into application limits, tolerance thresholds, etc., a designer may not have full confidence to say a value of X.X in a particular metric is “good enough,” but if they have two design options they can hopefully make a reasonable judgment on which is better (as long as the metric hasn’t been invalidated!).

-Chris



From: Germán Molina Larrain [mailto:germolinal at gmail.com]
Sent: Friday, December 02, 2016 7:27 AM
To: Radiance general discussion
Subject: [Radiance-general] Glare and visual confort indices -- Are they ready?

Dear List,

Even if this is not a question regarding the use of Radiance, it certainly is something related to this list or at least the expertise of its participants. I want to start a discussion.

As a small group of you may know, I am the developer of a Radiance-based lighting tool. This tool has the purpose of taking the state-of-the-art daylighting calculation methods and practices to industry. However, since industry sometimes just jump over a software, I am always worried about methods and tool being used incorrectly.

In this last regard, I have been wondering for a while whether I should add glare calculation capabilities or not. My impression is that they are incredibly easy to misuse. For example, at the NREL's 12th Radiance Workshop, Jan Wienold and Kevin Van Den Wymelenberg made Glare-oriented presentations that did not really agree much.

So, my question is: are glare indices, such as UGR, DGP, etc. etc. ready for use? Maybe only the Electric Lighting ones are ready? How about the Daylighting ones? I do not want to offer something that looks like a magic black-box, but which leads to incorrect results. I also know that having something is better than nothing, but that only works as long as that "something" helps guiding the design in the right direction.
Thanks very much in advance.
Germán
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.radiance-online.org/pipermail/radiance-general/attachments/20161202/8228aaa8/attachment.html>