Radiance-general Digest, Vol 93, Issue 18

I got quite excited by the topic... Acceptable,temperatures,radiation levels and wind speeds outdoors are an interest of mine. I have a colleague who has coined the term 'warm shade' to describe the concept many public spaces in New Zealand seek of staying in the warming rays of the sun while avoiding the worst of the UV from the same sun is a major focus especially in schools.

However, I am guessing from your explanation, confessing i do not understand it entirely, that you are trying to determine an outdoor illuminance that will provide a reasonable indoor illuminance? If that is the case, then is suspect there are so many variables other than VLT that you should be concerned with,that the approach needs to be re-thought. Size of window? Reflectivity of the other surfaces in the space? how much direct as opposed to bounced or diffuse light makes up your 100 Lux....

Can you draw a diagram (ASCII crude will do) that shows the light path you are tracing?

M

Michael Donn

[email protected]

···

Sent from my iPad

On 30/11/2011, at 9:03, "[email protected]" <[email protected]> wrote:

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Today's Topics:

  1. Daylighting metric for outdoor spaces (Mostapha Sadeghipour)
  2. Re: Daylighting metric for outdoor spaces (Guglielmetti, Robert)
  3. Re: Daylighting metric for outdoor spaces (Mostapha Sadeghipour)

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Message: 1
Date: Mon, 28 Nov 2011 15:59:00 -0600
From: Mostapha Sadeghipour <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: [Radiance-general] Daylighting metric for outdoor spaces
Message-ID:
   <CAAd_PgQNk3FjShpJaQPo0TwYHBd8PgwXZzMbtgnT90-Mf-HWtw@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi all,

I wonder if anybody is aware of a daylighting metric for outdoor spaces. Do
we have any scale for that or all the studies target the interior spaces so
far.

One way came to my mind is to start from the adjacent buildings and then
calculate backward. Is there a better way to do that?

Best,
Mostapha
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Message: 2
Date: Mon, 28 Nov 2011 15:07:39 -0700
From: "Guglielmetti, Robert" <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Daylighting metric for outdoor spaces
Message-ID: <CAF95348.BDD2%[email protected]>
Content-Type: text/plain; charset="us-ascii"

Hi Mostapha,

Interesting question. Generally, one can assume outdoor spaces are well-daylit unless they are located in Seattle or London. =)

What exactly do you mean by starting from the adjacent buildings and working backward? Defining a metric would be based on a totally different set of illumination criteria, glare tolerance, etc. It's an interesting question! What is your request based on, personal curiosity, or some new code/standard?

Rob Guglielmetti IESNA, LEED AP
Commercial Buildings Research Group
National Renewable Energy Laboratory
1617 Cole Blvd MS:RSF202
Golden, CO 80401
T. 303.275.4319
F. 303.630.2055
E. [email protected]

On 11/28/11 2:59 PM, "Mostapha Sadeghipour" <[email protected]<mailto:[email protected]>> wrote:

Hi all,

I wonder if anybody is aware of a daylighting metric for outdoor spaces. Do we have any scale for that or all the studies target the interior spaces so far.

One way came to my mind is to start from the adjacent buildings and then calculate backward. Is there a better way to do that?

Best,
Mostapha

------------------------------

Message: 3
Date: Mon, 28 Nov 2011 16:45:07 -0600
From: Mostapha Sadeghipour <[email protected]>
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Daylighting metric for outdoor spaces
Message-ID:
   <CAAd_PgSJvyquRSa0FQV4q_VozAks=Si1+c2qOeGeyEiL8LWyTA@mail.gmail.com>
Content-Type: text/plain; charset="iso-8859-1"

Hi Rob,

By coming backward I meant something like this:

If I assume > 100 lux and <2000 lux as the acceptable range. Then I
consider 60% of VLT for the glazing and 80% of reflectivity for ceiling
with a very rough calculation I need > 100 lux /(0.6*0.8) and <2000 lux
/(0.6*0.8) which is equal to > 208 lux and <4166 lux. I know that I
disregarded many effective design aspects except the VT of the glazing, and
this way of calculation is not that accurate but it was the first thing
came to my mind to make an assumption for outdoor spaces like streets.

The other possible way with the same concept is to put the sensors inside
the adjacent interior spaces and then use the available daylight metrics.
For an urban design study I wanted to avoid measuring light levels inside
the buildings as far as possible.

The climate is cloudy enough to make a new London and unfortunately the
only effective code is solar hours in 21st of December which makes no sense
to me. I think you literally count the number of solar hours in a
potentially always going to be an overcast day.

Mostapha

On Mon, Nov 28, 2011 at 4:07 PM, Guglielmetti, Robert < > [email protected]> wrote:

Hi Mostapha,

Interesting question. Generally, one can assume outdoor spaces are
well-daylit unless they are located in Seattle or London. =)

What exactly do you mean by starting from the adjacent buildings and
working backward? Defining a metric would be based on a totally different
set of illumination criteria, glare tolerance, etc. It's an interesting
question! What is your request based on, personal curiosity, or some new
code/standard?

Rob Guglielmetti IESNA, LEED AP
Commercial Buildings Research Group
National Renewable Energy Laboratory
1617 Cole Blvd MS:RSF202
Golden, CO 80401
T. 303.275.4319
F. 303.630.2055
E. [email protected]

On 11/28/11 2:59 PM, "Mostapha Sadeghipour" <[email protected]<mailto: >> [email protected]>> wrote:

Hi all,

I wonder if anybody is aware of a daylighting metric for outdoor spaces.
Do we have any scale for that or all the studies target the interior spaces
so far.

One way came to my mind is to start from the adjacent buildings and then
calculate backward. Is there a better way to do that?

Best,
Mostapha

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