UDI upper limits

Hi all,

I have seen several definitions of the UDI illuminance ranges around, with "UDI-e" (exceed) starting at 2000, 2500 or 3000lx. I really wonder what is the commonly used range these days? Can anyone here share some insight on this moving target for daylighting optimizations? :wink:

Cheers, Lars.

Hey Lars,

I've actually not heard of alternatives to the 2K lux UDI-e limit. Where
have you seen these proposed? Does John M. wanna weigh in on this?

Rob Guglielmetti
National Renewable Energy Laboratory (NREL)
Commercial Buildings Research Group
15013 Denver West Parkway MS:RSF202
Golden, CO 80401
303.275.4319
robert.guglielmetti@nrel.gov

路路路

On 12/10/12 7:07 AM, "Lars O. Grobe" <grobe@gmx.net> wrote:

Hi all,

I have seen several definitions of the UDI illuminance ranges around,
with "UDI-e" (exceed) starting at 2000, 2500 or 3000lx. I really wonder
what is the commonly used range these days? Can anyone here share some
insight on this moving target for daylighting optimizations? :wink:

Cheers, Lars.
_______________________________________________
Radiance-general mailing list
Radiance-general@radiance-online.org
http://www.radiance-online.org/mailman/listinfo/radiance-general

HMG research has not found an upper limit that relates to human subjective
responses with regard to glare or excessive daylight.

1. Heschong, L. Heschong Mahone Group.2012. Daylight Metrics. California
Energy Commission. Publication number: CEC-500-2012-053.
2. Saxena, M. et al., 2010. 61 Flavors of Daylight. In The Climate for
Efficiency is Now. 2010 ACEEE Summer Study on Energy Efficiency in
Buildings. Asilomar, CA: ACEEE Summer Study on Energy Efficiency in
Buildings, pp. 3.348颅3.361.

Some of my human factors research has shown very high levels can be
聦preferred鹿 but does lend some support for an upper limit similar to UDI
concept.
鲁An upper horizontal illuminance comfort-based threshold, as required by
Daylight Saturation Percentage or Useful Daylight Illuminance metrics,
should be set between 2000-4300 lux, but must be applied with an
understanding that some individuals may prefer values as high as 5000 lux
(during some parts of the year), thus confidently identifying only the most
extreme cases as uncomfortable.虏 (KVDW, 2012)

1. Van Den Wymelenberg, K.G., 2012. Evaluating Human Visual Preference and
Performance in an Office Environment Using Luminance-based Metrics.
Dissertation. Seattle, WA: University of Washington. Available at:
http://www.idlboise.com/papers/KevinVanDenWymelenberg-phd.
2. Van Den Wymelenberg, K.G., Inanici, M.N. & Johnson, P.W., 2010. The
Effect of Luminance Distribution Patterns on Occupant Preference in a Daylit
Office Environment. Leukos, 7(2), pp.103颅122.
聽聽
I believe Mardaljevic has been considering higher alternative thresholds as
well.

Kevin Van Den Wymelenberg, PhD
Integrated Design Lab 颅 Boise, Director
College of Art & Architecture, Assistant Professor
University of Idaho 颅 Boise Center
www.uidaho.edu/idl

ph. 208.724.9456 fx. 208.343.0001 306
S. 6th Street Boise, ID 83702

路路路

From: Rob Guglielmetti <Robert.Guglielmetti@nrel.gov>
Reply-To: Radiance general discussion <radiance-general@radiance-online.org>
Date: Mon, 10 Dec 2012 11:07:54 -0700
To: Radiance general discussion <radiance-general@radiance-online.org>
Subject: Re: [Radiance-general] UDI upper limits

Hey Lars,

I've actually not heard of alternatives to the 2K lux UDI-e limit. Where
have you seen these proposed? Does John M. wanna weigh in on this?

Rob Guglielmetti
National Renewable Energy Laboratory (NREL)
Commercial Buildings Research Group
15013 Denver West Parkway MS:RSF202
Golden, CO 80401
303.275.4319
robert.guglielmetti@nrel.gov

On 12/10/12 7:07 AM, "Lars O. Grobe" <grobe@gmx.net> wrote:

Hi all,

I have seen several definitions of the UDI illuminance ranges around,
with "UDI-e" (exceed) starting at 2000, 2500 or 3000lx. I really wonder
what is the commonly used range these days? Can anyone here share some
insight on this moving target for daylighting optimizations? :wink:

Cheers, Lars.
_______________________________________________
Radiance-general mailing list
Radiance-general@radiance-online.org
http://www.radiance-online.org/mailman/listinfo/radiance-general

_______________________________________________
Radiance-general mailing list
Radiance-general@radiance-online.org
http://www.radiance-online.org/mailman/listinfo/radiance-general

Hi Rob, Kevin & Radiance folks,

the latest 3K lux limit I found on John's site:

http://climate-based-daylighting.com/doku.php?id=academic:climate-based-daylight-modelling

In this paper, the 2500lx was mentioned:

http://www.thedaylightsite.com/filebank/Tools and Metrics - JM2.pdf (yes, the spaces are included in the URL)

The 2000lx has been used most as far as I am aware. I can understand that the upper limit is not hard (as Kevin said, it can be argued that such a limit does not make sense at all, which is still kind of an open discussion). Still I find it tricky to reference a UDI metric with all these definitions. I tend to use John's climate-based-daylighting.com as a (moving) reference, which would lead me to "latest revision of UDI-e is >3000lx.

Cheers, Lars.

Does John M. wanna weigh in on this?

I believe Mardaljevic has been considering higher alternative thresholds as well.

Yes, on both counts.

Original UDI of 100-2,000 lux was conceived around 2004, and was, with hindsight, a little too conservative regarding the upper limit. I suspect now that those studies giving preferred maxima less than 2,000 lux could well have been the older articles in our sample. Quite possible that work environments of around 20 years ago were less forgiving of high daylight illuminances, e.g. curved CRT screens, etc. It seems that the more recent studies are all nudging-up the preferred / tolerated upper limit.

Splitting the UDI range at the design level (e.g. 300 lux) was done in 2007 and applied to the (1st) VELUX study. For the past few years I've been using the values 100, 300 and 3,000 lux to define the four UDI ranges: fell-short (<100); supplementary (100 - 300); autonomous (300 - 3,000); and, exceeded (>3,000). For general daylighting use I don't see any need to alter the 100 and 300 lux bounds, but there may be good cause to increase the upper limit to 3,500 or 4,000 lux (greater?). I'll be doing some sensitivity tests on that seeing how it affects annual totals for the autonomous and exceeded ranges. It may not make much difference for many designs, at least in terms of UDI-autonomous and UDI-exceeded. Though that's not to say that it wouldn't have knock-on consequences for, say, annual predictions of DGP.

I do find the four range UDI scheme very useful to help evaluate (and communicate) the daylighting performance of a space -- especially when there are several facade variants to be considered and a simple slide transition reveals the impact of the design change in a manner that is very readily assimilated. For other, more specialist applications, I see no problem in adjusting the three defining lux levels to suit, e.g. 20, 50 and 200 for a gallery space where conservation is an issue.

So, UDI -- no fixed rules. Though a consensus for general daylighting applications may be forming around the 100, 300 and 3,000 (or 4,000?) lux values.

Cheers
John

John Mardaljevic
Professor of Building Daylight Modelling
School of Civil & Building Engineering
Loughborough University
Loughborough
Leicestershire
LE11 3TU, UK

Tel: +44 1509 222630 (Direct)
Tel: +44 1509 228529 (Pam Allen, secretary)

j.mardaljevic@lboro.ac.uk<mailto:j.mardaljevic@lboro.ac.uk>
http://www.lboro.ac.uk/departments/cv/staff/profile/367.html<http://www.lboro.ac.uk/departments/cv/>

Personal daylighting website:
http://climate-based-daylighting.com<http://climate-based-daylighting.com/>

John,

A very timely and useful response thank you. As you know the EFA (Education Funding Agency) in the UK has released its FOS (Facilities Output Specification) for the next generation of schools. The directive from the government was a higher standard of space for lower cost / m2.

We made the decision to drop daylight factors and move to CBDM for the next generation of schools and the topic of the UDI exceed level came up during the writing and testing of the baseline design and indeed it has come up again since as people try and create standard designs. As it stands the UDI autonomous was set at 100-2000 in the FOS. What this means for designers when you look at a balanced design, (thermal and lighting), you need to control heat gain with smaller external windows and therefore supplement the daylight from a secondary source. However, this costs money. E.g. Atria, lightwells, lightpipes etc.

What is interesting when you raise the UDI exceed from 2000 to 3000 then you can start again to design single sided lit spaces just as we had with DF's (indeed the type of rooms we are trying to stop building as the blinds are typically pulled down and the lights are turned on). My thought therefore is whether in raising UDIe to 3000 because say a person can typically accept that level of light, then means we have significantly increased the contrast in a single sided lit space. If we have, have we increased it to a level where parts of the space feel gloomy? Is the answer to move UDIa to 300-3000, does that matter much?

Regards

Andrew

路路路

__________________________
Andrew Bissell
B.Eng(Hons) C.Eng MSLL MCIBSE MIET
Lighting Design Director
Cundall Light4
Direct: +44 (0)161 200 1235
Mobile: +44 (0)7899 907 978
Office: +44 (0)161 244 5660
P Please consider the environment before printing this e-mail

From: John Mardaljevic [mailto:J.Mardaljevic@lboro.ac.uk]
Sent: 11 December 2012 20:27
To: radiance-general@radiance-online.org
Subject: Re: [Radiance-general] UDI upper limits

Does John M. wanna weigh in on this?

I believe Mardaljevic has been considering higher alternative thresholds as well.

Yes, on both counts.

Original UDI of 100-2,000 lux was conceived around 2004, and was, with hindsight, a little too conservative regarding the upper limit. I suspect now that those studies giving preferred maxima less than 2,000 lux could well have been the older articles in our sample. Quite possible that work environments of around 20 years ago were less forgiving of high daylight illuminances, e.g. curved CRT screens, etc. It seems that the more recent studies are all nudging-up the preferred / tolerated upper limit.

Splitting the UDI range at the design level (e.g. 300 lux) was done in 2007 and applied to the (1st) VELUX study. For the past few years I've been using the values 100, 300 and 3,000 lux to define the four UDI ranges: fell-short (<100); supplementary (100 - 300); autonomous (300 - 3,000); and, exceeded (>3,000). For general daylighting use I don't see any need to alter the 100 and 300 lux bounds, but there may be good cause to increase the upper limit to 3,500 or 4,000 lux (greater?). I'll be doing some sensitivity tests on that seeing how it affects annual totals for the autonomous and exceeded ranges. It may not make much difference for many designs, at least in terms of UDI-autonomous and UDI-exceeded. Though that's not to say that it wouldn't have knock-on consequences for, say, annual predictions of DGP.

I do find the four range UDI scheme very useful to help evaluate (and communicate) the daylighting performance of a space -- especially when there are several facade variants to be considered and a simple slide transition reveals the impact of the design change in a manner that is very readily assimilated. For other, more specialist applications, I see no problem in adjusting the three defining lux levels to suit, e.g. 20, 50 and 200 for a gallery space where conservation is an issue.

So, UDI -- no fixed rules. Though a consensus for general daylighting applications may be forming around the 100, 300 and 3,000 (or 4,000?) lux values.

Cheers
John

John Mardaljevic
Professor of Building Daylight Modelling
School of Civil & Building Engineering
Loughborough University
Loughborough
Leicestershire
LE11 3TU, UK

Tel: +44 1509 222630 (Direct)
Tel: +44 1509 228529 (Pam Allen, secretary)

j.mardaljevic@lboro.ac.uk<mailto:j.mardaljevic@lboro.ac.uk>
http://www.lboro.ac.uk/departments/cv/staff/profile/367.html<http://www.lboro.ac.uk/departments/cv/>

Personal daylighting website:
http://climate-based-daylighting.com<http://climate-based-daylighting.com/>
For further information about Cundall please visit http://www.cundall.com/News/World-Green-Building-Week.aspx
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Andrew,

I guess the outcome then starts to depend strongly on what you consider to be an acceptable value for UDI-exceeded. As the HMG work has indicated, that's a difficult one to determine empirically, and I for one can't suggest a 'target' value for the occurrence of UDI-e. I'd like to see a UDI sensitivity study carried for a large number of spaces covering a wide range of space types (i.e. glazing orientation, single-sided, multi-aspect, etc.) [1]. If, as you say, extending the UDI upper bound to 3,000 lux results in designs that we suspect are less good than using 2,000 lux, then we really do need to pause and scratch our heads a little to nail this one. However, your question suggests that going for UDI-a (300 - 3,000 lux) rather than 100 - 3,000 lux makes it less likely that the outcome is what we might have had with daylight factors. Seems plausible -- do we have anything yet to support this hypothesis?

I'd assumed that the 100 to 2,000 lux UDI range adopted in the FOS was simply taken from the Mk. 1 UDI formulation. Do you know if, instead, it was actually the result of some testing of range limits? By way of pedantry, suggest we use the term UDI to describe the complete range (e.g. 100 to 2,000 or, more recently, 100 to 3,000 lux), and UDI-autonomous for the occurrence between the design level (300 lux) and the upper limit (3,000 lux).

By the way, there is now a PDF available of the Lighting Supplement for the Dec 2012 CIBSE Journal:

Cheers
John

[1] I do have a suitable a building, but need to clear it with the clients.

John Mardaljevic
Professor of Building Daylight Modelling
School of Civil & Building Engineering
Loughborough University
Loughborough
Leicestershire
LE11 3TU, UK

Tel: +44 1509 222630 (Direct)
Tel: +44 1509 228529 (Pam Allen, secretary)

j.mardaljevic@lboro.ac.uk<mailto:j.mardaljevic@lboro.ac.uk>
http://www.lboro.ac.uk/departments/cv/staff/profile/367.html<http://www.lboro.ac.uk/departments/cv/>

Personal daylighting website:
http://climate-based-daylighting.com<http://climate-based-daylighting.com/>

路路路

On 11 Dec 2012, at 21:57, "Bissell, Andrew" <a.bissell@cundall.com<mailto:a.bissell@cundall.com>> wrote:

John,

A very timely and useful response thank you. As you know the EFA (Education Funding Agency) in the UK has released its FOS (Facilities Output Specification) for the next generation of schools. The directive from the government was a higher standard of space for lower cost / m2.

We made the decision to drop daylight factors and move to CBDM for the next generation of schools and the topic of the UDI exceed level came up during the writing and testing of the baseline design and indeed it has come up again since as people try and create standard designs. As it stands the UDI autonomous was set at 100-2000 in the FOS. What this means for designers when you look at a balanced design, (thermal and lighting), you need to control heat gain with smaller external windows and therefore supplement the daylight from a secondary source. However, this costs money. E.g. Atria, lightwells, lightpipes etc.

What is interesting when you raise the UDI exceed from 2000 to 3000 then you can start again to design single sided lit spaces just as we had with DF鈥檚 (indeed the type of rooms we are trying to stop building as the blinds are typically pulled down and the lights are turned on). My thought therefore is whether in raising UDIe to 3000 because say a person can typically accept that level of light, then means we have significantly increased the contrast in a single sided lit space. If we have, have we increased it to a level where parts of the space feel gloomy? Is the answer to move UDIa to 300-3000, does that matter much?

Regards

Andrew
__________________________
Andrew Bissell
B.Eng(Hons) C.Eng MSLL MCIBSE MIET
Lighting Design Director
Cundall Light4
Direct: +44 (0)161 200 1235
Mobile: +44 (0)7899 907 978
Office: +44 (0)161 244 5660
P Please consider the environment before printing this e-mail