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

[Germán Molina Larrain]

Thanks, Chris! I believe this question is meant to be answer based on
opinions.

I agree that people need to know what they are doing... metrics ALWAYS
should be carefuly chosen, even if they have been validated (that is why I
have intentions of writing a good documentation). That being said, I am not
quite sure (just because of my own ignorance) if Evalglare and DGP, for
example, are ready for design use. I mean, *Will it produce useful
information in all or most or enough design cases, provided that all the
parameters are set correctly? Or is it limited to certain positions and
room configurations? How about the other metrics?* I personally usually
design using illuminance-based metrics and am not quite sure when would I
use luminance-based ones.

I am very new at glare, but I have heard people I respect say that we still
do not know much about it, thus my question. Is it worth including such
features in Groundhog? I want to keep this tool at the state-of-the-art,
but only if state-of-the-art methods are ready for use.

Kind regards,

Germán



2016-12-02 11:10 GMT-03:00 Christopher Rush <Christopher.Rush at arup.com>:

> 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 even the outdated metrics may still be referenced in some governing design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
>
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>
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