# Daylighting metric for outdoor spaces

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

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

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

_______________________________________________
[email protected]

Hi Mostapha,

For an urban design study I wanted to avoid measuring light levels inside the buildings as far as possible.

How about using cumulative values, say annual or maybe monthly? You could also look at just the hours of occupancy. Some examples here:

The image for London clearly shows the effect of tall buildings reducing the ground level cumulative illuminance (actually, irradiance in the legend but just x 100 to estimate klux-hrs / yr).

Best
John

Institute of Energy and Sustainable Development
De Montfort University, The Gateway, Leicester, LE1 9BH, UK
Tel: +44 (0) 116 257 7972

Hi John, Michael, et al.

Michael,

Sorry if it wasn't clear enough. I think you get the concept. Yes! I wonder
if there is a number to determine the outdoor illuminance to provide enough
illuminance level inside. What you are saying is true and the effective
parameters are much more than only VLT and ceiling reflectance but if I
want to consider all of them I should modify the geometry and run the
lighting simulation.

The way I did the ray-tracing in my mind was the simplest possible backward
ray-tracing. I started from the sensor inside, then traced only one ray
upward and bounced it from the ceiling to the glazing. So illuminance level
inside the space is equal to illuminance level outside the glazing (on the
envelope of the building that I can simulate) multiply by VLT of the
glazing multiply by the reflectance of the ceiling. In this way I can make
a target for the illuminance level on the envelopes rather than indoor.

The question could be more general though and thinking about the relation
between outdoor illuminance level and then the external envelopes.

John,

Thank you for the great link! This is exactly what I'm talking about. I
actually ran the accumulative annual study. That's true that cumulative
result shows you get less illuminace in more dense areas but what are the
cutting levels? Do we have the concept of over-daylit for outdoors?

For example if I calculate the availability of useful daylight illuminance
based on 100 lux and 2500 lux for working hours and calculate the result
based on the percentage of hours a large portion of the well-daylit outdoor
spaces will be considered as over-daylit because they receive more than
2500 lux, and then the more dark outdoor spaces located in Seattle or
London (hi Rob!) will be assumed as well-daylit since they will be in the
range. We already knew this is not true and the spaces next to an outdoor
space with 150 lux horizontal illuminance level cannot be well-daylit.

Maybe we can say there should be no upper-limit for outdoor illuminace
level since we can always mitigate the light level by building envelope
design, but what is the lower limit then?

Best,
Mostapha

PS.1: I liked the concept of "warm shade" so much. So interesting to think
about.... Can you send me a link to the paper or any other resources?

···

On Wed, Nov 30, 2011 at 10:26 AM, John Mardaljevic <[email protected]> wrote:

Hi Mostapha,

> For an urban design study I wanted to avoid measuring light levels
inside the buildings as far as possible.

How about using cumulative values, say annual or maybe monthly? You could
also look at just the hours of occupancy. Some examples here:

The image for London clearly shows the effect of tall buildings reducing
the ground level cumulative illuminance (actually, irradiance in the legend
but just x 100 to estimate klux-hrs / yr).

Best
John

Institute of Energy and Sustainable Development
De Montfort University, The Gateway, Leicester, LE1 9BH, UK
Tel: +44 (0) 116 257 7972

_______________________________________________
[email protected]

Hi Mostapha,

BRE has a metric - Vertical Skylight Component - for what you describe. It is intended as a planning tool to insure that housing blocks are not located to close together. It is also used in rights to light litigation in the UK. It's independent of climate though, it's mainly to ensure that an appropriate percentage of daylight is made available at the window (i.e. not too many tall buildings nearby). I'm not saying it's a great metric, but it's commonly used for what you want to do.

VSC is commonly coupled with the hours of sunshine in a courtyard metric you mentioned in an earlier email. I just want to point out that this is not a daylight metric but a planning tool to ensure that courtyards are not more damp and dank than an open park in the same climate. For example, if you have a week of damp overcast weather both your open space and your courtyard will be damp, but then when you have a day of sunshine your park will dry up, but your courtyard may not if there isn't sufficient sun penetration. A courtyard that stays damp gets even worse in the next week of wet weather. The metric is intended to prevent mold, mildew and perpetually damp courtyards. So in reality this metric is more applicable to climates like London and Seattle than Phoenix or Dubai.

Andy

···

On Nov 30, 2011, at 9:31 AM, Mostapha Sadeghipour wrote:

Hi John, Michael, et al.

Michael,

Sorry if it wasn't clear enough. I think you get the concept. Yes! I wonder if there is a number to determine the outdoor illuminance to provide enough illuminance level inside. What you are saying is true and the effective parameters are much more than only VLT and ceiling reflectance but if I want to consider all of them I should modify the geometry and run the lighting simulation.

The way I did the ray-tracing in my mind was the simplest possible backward ray-tracing. I started from the sensor inside, then traced only one ray upward and bounced it from the ceiling to the glazing. So illuminance level inside the space is equal to illuminance level outside the glazing (on the envelope of the building that I can simulate) multiply by VLT of the glazing multiply by the reflectance of the ceiling. In this way I can make a target for the illuminance level on the envelopes rather than indoor.

The question could be more general though and thinking about the relation between outdoor illuminance level and then the external envelopes.

John,

Thank you for the great link! This is exactly what I'm talking about. I actually ran the accumulative annual study. That's true that cumulative result shows you get less illuminace in more dense areas but what are the cutting levels? Do we have the concept of over-daylit for outdoors?

For example if I calculate the availability of useful daylight illuminance based on 100 lux and 2500 lux for working hours and calculate the result based on the percentage of hours a large portion of the well-daylit outdoor spaces will be considered as over-daylit because they receive more than 2500 lux, and then the more dark outdoor spaces located in Seattle or London (hi Rob!) will be assumed as well-daylit since they will be in the range. We already knew this is not true and the spaces next to an outdoor space with 150 lux horizontal illuminance level cannot be well-daylit.

Maybe we can say there should be no upper-limit for outdoor illuminace level since we can always mitigate the light level by building envelope design, but what is the lower limit then?

Best,
Mostapha

PS.1: I liked the concept of "warm shade" so much. So interesting to think about.... Can you send me a link to the paper or any other resources?

On Wed, Nov 30, 2011 at 10:26 AM, John Mardaljevic <[email protected]> wrote:
Hi Mostapha,

> For an urban design study I wanted to avoid measuring light levels inside the buildings as far as possible.

How about using cumulative values, say annual or maybe monthly? You could also look at just the hours of occupancy. Some examples here:

The image for London clearly shows the effect of tall buildings reducing the ground level cumulative illuminance (actually, irradiance in the legend but just x 100 to estimate klux-hrs / yr).

Best
John

Institute of Energy and Sustainable Development
De Montfort University, The Gateway, Leicester, LE1 9BH, UK
Tel: +44 (0) 116 257 7972

_______________________________________________
[email protected]

_______________________________________________
[email protected]

Hi Andy,

Thank you for clarification and explanation. It was so informative.

I agree that using hours of sunshine (sunlight hours) in this way totally
make sense however in the code I mentioned it was a metric for building
envelopes (e.g. two hours of sunlight hours in 21st December is needed for
residential buildings).

As you said the weakness of metrics like VSC or Daylight Factor
(SC+ERC+IRC) is not being climate-based and orientation sensitive but maybe
this is the best possible way for now.

Thanks,
Mostapha

···

On Wed, Nov 30, 2011 at 12:18 PM, Andy McNeil <[email protected]> wrote:

Hi Mostapha,

BRE has a metric - Vertical Skylight Component - for what you describe.
It is intended as a planning tool to insure that housing blocks are not
located to close together. It is also used in rights to light litigation
in the UK. It's independent of climate though, it's mainly to ensure that
an appropriate percentage of daylight is made available at the window (i.e.
not too many tall buildings nearby). I'm not saying it's a great metric,
but it's commonly used for what you want to do.

VSC is commonly coupled with the hours of sunshine in a courtyard metric
you mentioned in an earlier email. I just want to point out that this is
not a daylight metric but a planning tool to ensure that courtyards are not
more damp and dank than an open park in the same climate. For example, if
you have a week of damp overcast weather both your open space and your
courtyard will be damp, but then when you have a day of sunshine your park
will dry up, but your courtyard may not if there isn't sufficient sun
penetration. A courtyard that stays damp gets even worse in the next week
of wet weather. The metric is intended to prevent mold, mildew and
perpetually damp courtyards. So in reality this metric is more applicable
to climates like London and Seattle than Phoenix or Dubai.

Andy

On Nov 30, 2011, at 9:31 AM, Mostapha Sadeghipour wrote:

Hi John, Michael, et al.

Michael,

Sorry if it wasn't clear enough. I think you get the concept. Yes! I
wonder if there is a number to determine the outdoor illuminance to provide
enough illuminance level inside. What you are saying is true and the
effective parameters are much more than only VLT and ceiling reflectance
but if I want to consider all of them I should modify the geometry and run
the lighting simulation.

The way I did the ray-tracing in my mind was the simplest possible
backward ray-tracing. I started from the sensor inside, then traced only
one ray upward and bounced it from the ceiling to the glazing. So
illuminance level inside the space is equal to illuminance level outside
the glazing (on the envelope of the building that I can simulate) multiply
by VLT of the glazing multiply by the reflectance of the ceiling. In this
way I can make a target for the illuminance level on the envelopes rather
than indoor.

The question could be more general though and thinking about the relation
between outdoor illuminance level and then the external envelopes.

John,

Thank you for the great link! This is exactly what I'm talking about. I
actually ran the accumulative annual study. That's true that cumulative
result shows you get less illuminace in more dense areas but what are the
cutting levels? Do we have the concept of over-daylit for outdoors?

For example if I calculate the availability of useful daylight illuminance
based on 100 lux and 2500 lux for working hours and calculate the result
based on the percentage of hours a large portion of the well-daylit outdoor
spaces will be considered as over-daylit because they receive more than
2500 lux, and then the more dark outdoor spaces located in Seattle or
London (hi Rob!) will be assumed as well-daylit since they will be in the
range. We already knew this is not true and the spaces next to an outdoor
space with 150 lux horizontal illuminance level cannot be well-daylit.

Maybe we can say there should be no upper-limit for outdoor illuminace
level since we can always mitigate the light level by building envelope
design, but what is the lower limit then?

Best,
Mostapha

PS.1: I liked the concept of "warm shade" so much. So interesting to think
about.... Can you send me a link to the paper or any other resources?

On Wed, Nov 30, 2011 at 10:26 AM, John Mardaljevic <[email protected]> wrote:

Hi Mostapha,

> For an urban design study I wanted to avoid measuring light levels
inside the buildings as far as possible.

How about using cumulative values, say annual or maybe monthly? You
could also look at just the hours of occupancy. Some examples here:

The image for London clearly shows the effect of tall buildings reducing
the ground level cumulative illuminance (actually, irradiance in the legend
but just x 100 to estimate klux-hrs / yr).

Best
John

Institute of Energy and Sustainable Development
De Montfort University, The Gateway, Leicester, LE1 9BH, UK
Tel: +44 (0) 116 257 7972

_______________________________________________
[email protected]

_______________________________________________
[email protected]

_______________________________________________
[email protected]

Hi Mostapha

I asked my colleague Christina MacKay ([email protected]) for references / inks to her papers defining 'warm shade', and received this list:

Please refer to the following key papers -

Mackay, C. (2009). Environmental Shade for Protection from UVR: A Design & Teaching Resource. Proceedings of the 26th Conference on Passive and Low Energy Architecture (PLEA). 22-24 June 2009. (pp 314-319). Quebec City, Canada.
Mackay, C. (2006). Towards a safe sun-bathing canopy. The 23rd Conference on Passive and Low Energy Architecture. (pp. 581-586). Geneva, Switzerland.
Mackay, C A. (2005, April). Living outside in the sun - a historical review of New Zealand outdoor living spaces. Inside-outside symposium, IDEA, RMIT. Melbourne, Australia.
Gies, P., & Mackay, C A. (2004). Measurements of solar UVR protection provided by shade structures in New Zealand primary schools. Photochemistry and Photobiology, 80. (pp. 334-339). http:www3.interscience.wiley.com/cgi-bin/fulltext/11921593/htmlstart.
Mackay, C A. (2003). Designing safe and comfortable indoor living spaces. Passive Low Energy Architecture, Proceedings of 20th International Conference, November 2003. Ins by Bustamante, W. & Collados, E. (Eds). Pontificia Universidad Catolica de Chile. B-24. (pp. 321-325). Santiago, Chile.
Mackay, C A. (2003). Sunshade Design in New Zealand Primary Schools. Passive Low Energy Architecture - Proceedings of 20th International Conference, November 2003. Ins by Bustamante, W. & Collados, E. (Eds). Pontificia Universidad Catolica de Chile. A-18. (pp. 143-150). Santiago, Chile.

Cheers
Christina

···

------------------------------------
Victoria University of Wellington School of Architecture
Michael Donn
[email protected]
PO Box 600
139 Vivian St
Wellington
New Zealand
tel: +64 4 463 6221
fax: +64 4 463 6204
mobile: +64 21 611 280
Skype ID:the_donn
------------------------------------

-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Friday, December 02, 2011 9:00 AM
To: [email protected]
Subject: Radiance-general Digest, Vol 94, Issue 1

Send Radiance-general mailing list submissions to
[email protected]

To subscribe or unsubscribe via the World Wide Web, visit
or, via email, send a message with subject or body 'help' to
[email protected]

You can reach the person managing the list at
[email protected]

than "Re: Contents of Radiance-general digest..."

Today's Topics:

1. Re: Daylighting metric for outdoor spaces (Mostapha Sadeghipour)

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

Message: 1
Date: Wed, 30 Nov 2011 19:27:27 -0600
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Daylighting metric for outdoor spaces
Message-ID:
Content-Type: text/plain; charset="iso-8859-1"

Hi Andy,

Thank you for clarification and explanation. It was so informative.

I agree that using hours of sunshine (sunlight hours) in this way totally
make sense however in the code I mentioned it was a metric for building
envelopes (e.g. two hours of sunlight hours in 21st December is needed for
residential buildings).

As you said the weakness of metrics like VSC or Daylight Factor
(SC+ERC+IRC) is not being climate-based and orientation sensitive but maybe
this is the best possible way for now.

Thanks,
Mostapha

On Wed, Nov 30, 2011 at 12:18 PM, Andy McNeil <[email protected]> wrote:

Hi Mostapha,

BRE has a metric - Vertical Skylight Component - for what you describe.
It is intended as a planning tool to insure that housing blocks are not
located to close together. It is also used in rights to light litigation
in the UK. It's independent of climate though, it's mainly to ensure that
an appropriate percentage of daylight is made available at the window (i.e.
not too many tall buildings nearby). I'm not saying it's a great metric,
but it's commonly used for what you want to do.

VSC is commonly coupled with the hours of sunshine in a courtyard metric
you mentioned in an earlier email. I just want to point out that this is
not a daylight metric but a planning tool to ensure that courtyards are not
more damp and dank than an open park in the same climate. For example, if
you have a week of damp overcast weather both your open space and your
courtyard will be damp, but then when you have a day of sunshine your park
will dry up, but your courtyard may not if there isn't sufficient sun
penetration. A courtyard that stays damp gets even worse in the next week
of wet weather. The metric is intended to prevent mold, mildew and
perpetually damp courtyards. So in reality this metric is more applicable
to climates like London and Seattle than Phoenix or Dubai.

Andy

On Nov 30, 2011, at 9:31 AM, Mostapha Sadeghipour wrote:

Hi John, Michael, et al.

Michael,

Sorry if it wasn't clear enough. I think you get the concept. Yes! I
wonder if there is a number to determine the outdoor illuminance to provide
enough illuminance level inside. What you are saying is true and the
effective parameters are much more than only VLT and ceiling reflectance
but if I want to consider all of them I should modify the geometry and run
the lighting simulation.

The way I did the ray-tracing in my mind was the simplest possible
backward ray-tracing. I started from the sensor inside, then traced only
one ray upward and bounced it from the ceiling to the glazing. So
illuminance level inside the space is equal to illuminance level outside
the glazing (on the envelope of the building that I can simulate) multiply
by VLT of the glazing multiply by the reflectance of the ceiling. In this
way I can make a target for the illuminance level on the envelopes rather
than indoor.

The question could be more general though and thinking about the relation
between outdoor illuminance level and then the external envelopes.

John,

Thank you for the great link! This is exactly what I'm talking about. I
actually ran the accumulative annual study. That's true that cumulative
result shows you get less illuminace in more dense areas but what are the
cutting levels? Do we have the concept of over-daylit for outdoors?

For example if I calculate the availability of useful daylight illuminance
based on 100 lux and 2500 lux for working hours and calculate the result
based on the percentage of hours a large portion of the well-daylit outdoor
spaces will be considered as over-daylit because they receive more than
2500 lux, and then the more dark outdoor spaces located in Seattle or
London (hi Rob!) will be assumed as well-daylit since they will be in the
range. We already knew this is not true and the spaces next to an outdoor
space with 150 lux horizontal illuminance level cannot be well-daylit.

Maybe we can say there should be no upper-limit for outdoor illuminace
level since we can always mitigate the light level by building envelope
design, but what is the lower limit then?

Best,
Mostapha

PS.1: I liked the concept of "warm shade" so much. So interesting to think
about.... Can you send me a link to the paper or any other resources?

On Wed, Nov 30, 2011 at 10:26 AM, John Mardaljevic <[email protected]> wrote:

Hi Mostapha,

> For an urban design study I wanted to avoid measuring light levels
inside the buildings as far as possible.

How about using cumulative values, say annual or maybe monthly? You
could also look at just the hours of occupancy. Some examples here:

The image for London clearly shows the effect of tall buildings reducing
the ground level cumulative illuminance (actually, irradiance in the legend
but just x 100 to estimate klux-hrs / yr).

Best
John

Institute of Energy and Sustainable Development
De Montfort University, The Gateway, Leicester, LE1 9BH, UK
Tel: +44 (0) 116 257 7972

_______________________________________________
[email protected]

_______________________________________________
[email protected]

_______________________________________________
[email protected]

-------------- next part --------------
An HTML attachment was scrubbed...

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

_______________________________________________
[email protected]

End of Radiance-general Digest, Vol 94, Issue 1
***********************************************

Hi Michael,

Thank you for both emails today. I knew that statement is flawed, and I
think I mentioned that before. Nevertheless thank you for the links.

I think the best way, to find the answer, is to run series of annual
simulations for different locations. Will do soon.

Mostapha

···

On Thu, Dec 1, 2011 at 10:19 PM, Michael Donn <[email protected]>wrote:

Hi Mostapha

I asked my colleague Christina MacKay ([email protected]) for
references / inks to her papers defining 'warm shade', and received this
list:

Please refer to the following key papers -

Mackay, C. (2009). Environmental Shade for Protection from UVR: A Design &
Teaching Resource. Proceedings of the 26th Conference on Passive and Low
Energy Architecture (PLEA). 22-24 June 2009. (pp 314-319). Quebec City,
Mackay, C. (2006). Towards a safe sun-bathing canopy. The 23rd Conference
on Passive and Low Energy Architecture. (pp. 581-586). Geneva, Switzerland.
Mackay, C A. (2005, April). Living outside in the sun - a historical
review of New Zealand outdoor living spaces. Inside-outside symposium,
IDEA, RMIT. Melbourne, Australia.
Gies, P., & Mackay, C A. (2004). Measurements of solar UVR protection
provided by shade structures in New Zealand primary schools. Photochemistry
and Photobiology, 80. (pp. 334-339). http:
www3.interscience.wiley.com/cgi-bin/fulltext/11921593/htmlstart.
Mackay, C A. (2003). Designing safe and comfortable indoor living spaces.
Passive Low Energy Architecture, Proceedings of 20th International
Conference, November 2003. Ins by Bustamante, W. & Collados, E. (Eds).
Pontificia Universidad Catolica de Chile. B-24. (pp. 321-325). Santiago,
Chile.
Passive Low Energy Architecture - Proceedings of 20th International
Conference, November 2003. Ins by Bustamante, W. & Collados, E. (Eds).
Pontificia Universidad Catolica de Chile. A-18. (pp. 143-150). Santiago,
Chile.

Cheers
Christina

------------------------------------
Victoria University of Wellington School of Architecture
Michael Donn
[email protected]
PO Box 600
139 Vivian St
Wellington
New Zealand
tel: +64 4 463 6221
fax: +64 4 463 6204
mobile: +64 21 611 280
Skype ID:the_donn
------------------------------------

-----Original Message-----
From: [email protected] [mailto:
[email protected]]
Sent: Friday, December 02, 2011 9:00 AM
To: [email protected]
Subject: Radiance-general Digest, Vol 94, Issue 1

Send Radiance-general mailing list submissions to
[email protected]

To subscribe or unsubscribe via the World Wide Web, visit
or, via email, send a message with subject or body 'help' to
[email protected]

You can reach the person managing the list at
[email protected]

than "Re: Contents of Radiance-general digest..."

Today's Topics:

1. Re: Daylighting metric for outdoor spaces (Mostapha Sadeghipour)

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

Message: 1
Date: Wed, 30 Nov 2011 19:27:27 -0600
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Daylighting metric for outdoor spaces
Message-ID:
>
Content-Type: text/plain; charset="iso-8859-1"

Hi Andy,

Thank you for clarification and explanation. It was so informative.

I agree that using hours of sunshine (sunlight hours) in this way totally
make sense however in the code I mentioned it was a metric for building
envelopes (e.g. two hours of sunlight hours in 21st December is needed for
residential buildings).

As you said the weakness of metrics like VSC or Daylight Factor
(SC+ERC+IRC) is not being climate-based and orientation sensitive but maybe
this is the best possible way for now.

Thanks,
Mostapha

On Wed, Nov 30, 2011 at 12:18 PM, Andy McNeil <[email protected]> wrote:

> Hi Mostapha,
>
> BRE has a metric - Vertical Skylight Component - for what you describe.
> It is intended as a planning tool to insure that housing blocks are not
> located to close together. It is also used in rights to light litigation
> in the UK. It's independent of climate though, it's mainly to ensure
that
> an appropriate percentage of daylight is made available at the window
(i.e.
> not too many tall buildings nearby). I'm not saying it's a great metric,
> but it's commonly used for what you want to do.
>
> VSC is commonly coupled with the hours of sunshine in a courtyard metric
> you mentioned in an earlier email. I just want to point out that this is
> not a daylight metric but a planning tool to ensure that courtyards are
not
> more damp and dank than an open park in the same climate. For example,
if
> you have a week of damp overcast weather both your open space and your
> courtyard will be damp, but then when you have a day of sunshine your
park
> will dry up, but your courtyard may not if there isn't sufficient sun
> penetration. A courtyard that stays damp gets even worse in the next
week
> of wet weather. The metric is intended to prevent mold, mildew and
> perpetually damp courtyards. So in reality this metric is more
applicable
> to climates like London and Seattle than Phoenix or Dubai.
>
> Andy
>
>
>
> On Nov 30, 2011, at 9:31 AM, Mostapha Sadeghipour wrote:
>
> Hi John, Michael, et al.
>
> Michael,
>
> Sorry if it wasn't clear enough. I think you get the concept. Yes! I
> wonder if there is a number to determine the outdoor illuminance to
provide
> enough illuminance level inside. What you are saying is true and the
> effective parameters are much more than only VLT and ceiling reflectance
> but if I want to consider all of them I should modify the geometry and
run
> the lighting simulation.
>
> The way I did the ray-tracing in my mind was the simplest possible
> backward ray-tracing. I started from the sensor inside, then traced only
> one ray upward and bounced it from the ceiling to the glazing. So
> illuminance level inside the space is equal to illuminance level outside
> the glazing (on the envelope of the building that I can simulate)
multiply
> by VLT of the glazing multiply by the reflectance of the ceiling. In this
> way I can make a target for the illuminance level on the envelopes rather
> than indoor.
>
> The question could be more general though and thinking about the relation
> between outdoor illuminance level and then the external envelopes.
>
> John,
>
> Thank you for the great link! This is exactly what I'm talking about. I
> actually ran the accumulative annual study. That's true that cumulative
> result shows you get less illuminace in more dense areas but what are the
> cutting levels? Do we have the concept of over-daylit for outdoors?
>
> For example if I calculate the availability of useful daylight
illuminance
> based on 100 lux and 2500 lux for working hours and calculate the result
> based on the percentage of hours a large portion of the well-daylit
outdoor
> spaces will be considered as over-daylit because they receive more than
> 2500 lux, and then the more dark outdoor spaces located in Seattle or
> London (hi Rob!) will be assumed as well-daylit since they will be in the
> range. We already knew this is not true and the spaces next to an outdoor
> space with 150 lux horizontal illuminance level cannot be well-daylit.
>
> Maybe we can say there should be no upper-limit for outdoor illuminace
> level since we can always mitigate the light level by building envelope
> design, but what is the lower limit then?
>
> Best,
> Mostapha
>
> PS.1: I liked the concept of "warm shade" so much. So interesting to
think
> about.... Can you send me a link to the paper or any other resources?
>
>
> On Wed, Nov 30, 2011 at 10:26 AM, John Mardaljevic <[email protected]> wrote:
>
>> Hi Mostapha,
>>
>> > For an urban design study I wanted to avoid measuring light levels
>> inside the buildings as far as possible.
>>
>> How about using cumulative values, say annual or maybe monthly? You
>> could also look at just the hours of occupancy. Some examples here:
>>
>>
>> The image for London clearly shows the effect of tall buildings reducing
>> the ground level cumulative illuminance (actually, irradiance in the
legend
>> but just x 100 to estimate klux-hrs / yr).
>>
>> Best
>> John
>>
>> Institute of Energy and Sustainable Development
>> De Montfort University, The Gateway, Leicester, LE1 9BH, UK
>> Tel: +44 (0) 116 257 7972
>>
>> [email protected]
>> http://www.iesd.dmu.ac.uk/~jm
>>
>>
>> _______________________________________________
>> [email protected]
>>
>
> _______________________________________________
> [email protected]
>
>
>
> _______________________________________________
> [email protected]
>
>
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End of Radiance-general Digest, Vol 94, Issue 1
***********************************************

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[email protected]

I found the presentations from Solar Energy at Urban Scale Workshop really
helpful to me in the related subject:
http://www.utc.fr/seus/iso_album/abstract_seus.pdf

You can find John's presentation here as well
Regards,
Mostapha

···

On Thu, Dec 1, 2011 at 10:34 PM, Mostapha Sadeghipour <[email protected] > wrote:

Hi Michael,

Thank you for both emails today. I knew that statement is flawed, and I
think I mentioned that before. Nevertheless thank you for the links.

I think the best way, to find the answer, is to run series of annual
simulations for different locations. Will do soon.

Mostapha

On Thu, Dec 1, 2011 at 10:19 PM, Michael Donn <[email protected]>wrote:

Hi Mostapha

I asked my colleague Christina MacKay ([email protected]) for
references / inks to her papers defining 'warm shade', and received this
list:

Please refer to the following key papers -

Mackay, C. (2009). Environmental Shade for Protection from UVR: A Design
& Teaching Resource. Proceedings of the 26th Conference on Passive and Low
Energy Architecture (PLEA). 22-24 June 2009. (pp 314-319). Quebec City,
Mackay, C. (2006). Towards a safe sun-bathing canopy. The 23rd Conference
on Passive and Low Energy Architecture. (pp. 581-586). Geneva, Switzerland.
Mackay, C A. (2005, April). Living outside in the sun - a historical
review of New Zealand outdoor living spaces. Inside-outside symposium,
IDEA, RMIT. Melbourne, Australia.
Gies, P., & Mackay, C A. (2004). Measurements of solar UVR protection
provided by shade structures in New Zealand primary schools. Photochemistry
and Photobiology, 80. (pp. 334-339). http:
www3.interscience.wiley.com/cgi-bin/fulltext/11921593/htmlstart.
Mackay, C A. (2003). Designing safe and comfortable indoor living spaces.
Passive Low Energy Architecture, Proceedings of 20th International
Conference, November 2003. Ins by Bustamante, W. & Collados, E. (Eds).
Pontificia Universidad Catolica de Chile. B-24. (pp. 321-325). Santiago,
Chile.
Passive Low Energy Architecture - Proceedings of 20th International
Conference, November 2003. Ins by Bustamante, W. & Collados, E. (Eds).
Pontificia Universidad Catolica de Chile. A-18. (pp. 143-150). Santiago,
Chile.

Cheers
Christina

------------------------------------
Victoria University of Wellington School of Architecture
Michael Donn
[email protected]
PO Box 600
139 Vivian St
Wellington
New Zealand
tel: +64 4 463 6221
fax: +64 4 463 6204
mobile: +64 21 611 280
Skype ID:the_donn
------------------------------------

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Subject: Radiance-general Digest, Vol 94, Issue 1

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than "Re: Contents of Radiance-general digest..."

Today's Topics:

1. Re: Daylighting metric for outdoor spaces (Mostapha Sadeghipour)

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

Message: 1
Date: Wed, 30 Nov 2011 19:27:27 -0600
To: Radiance general discussion <[email protected]>
Subject: Re: [Radiance-general] Daylighting metric for outdoor spaces
Message-ID:
[email protected]>
Content-Type: text/plain; charset="iso-8859-1"

Hi Andy,

Thank you for clarification and explanation. It was so informative.

I agree that using hours of sunshine (sunlight hours) in this way totally
make sense however in the code I mentioned it was a metric for building
envelopes (e.g. two hours of sunlight hours in 21st December is needed for
residential buildings).

As you said the weakness of metrics like VSC or Daylight Factor
(SC+ERC+IRC) is not being climate-based and orientation sensitive but
maybe
this is the best possible way for now.

Thanks,
Mostapha

On Wed, Nov 30, 2011 at 12:18 PM, Andy McNeil <[email protected]> wrote:

> Hi Mostapha,
>
> BRE has a metric - Vertical Skylight Component - for what you describe.
> It is intended as a planning tool to insure that housing blocks are not
> located to close together. It is also used in rights to light
litigation
> in the UK. It's independent of climate though, it's mainly to ensure
that
> an appropriate percentage of daylight is made available at the window
(i.e.
> not too many tall buildings nearby). I'm not saying it's a great
metric,
> but it's commonly used for what you want to do.
>
> VSC is commonly coupled with the hours of sunshine in a courtyard metric
> you mentioned in an earlier email. I just want to point out that this
is
> not a daylight metric but a planning tool to ensure that courtyards are
not
> more damp and dank than an open park in the same climate. For example,
if
> you have a week of damp overcast weather both your open space and your
> courtyard will be damp, but then when you have a day of sunshine your
park
> will dry up, but your courtyard may not if there isn't sufficient sun
> penetration. A courtyard that stays damp gets even worse in the next
week
> of wet weather. The metric is intended to prevent mold, mildew and
> perpetually damp courtyards. So in reality this metric is more
applicable
> to climates like London and Seattle than Phoenix or Dubai.
>
> Andy
>
>
>
> On Nov 30, 2011, at 9:31 AM, Mostapha Sadeghipour wrote:
>
> Hi John, Michael, et al.
>
> Michael,
>
> Sorry if it wasn't clear enough. I think you get the concept. Yes! I
> wonder if there is a number to determine the outdoor illuminance to
provide
> enough illuminance level inside. What you are saying is true and the
> effective parameters are much more than only VLT and ceiling reflectance
> but if I want to consider all of them I should modify the geometry and
run
> the lighting simulation.
>
> The way I did the ray-tracing in my mind was the simplest possible
> backward ray-tracing. I started from the sensor inside, then traced only
> one ray upward and bounced it from the ceiling to the glazing. So
> illuminance level inside the space is equal to illuminance level outside
> the glazing (on the envelope of the building that I can simulate)
multiply
> by VLT of the glazing multiply by the reflectance of the ceiling. In
this
> way I can make a target for the illuminance level on the envelopes
rather
> than indoor.
>
> The question could be more general though and thinking about the
relation
> between outdoor illuminance level and then the external envelopes.
>
> John,
>
> Thank you for the great link! This is exactly what I'm talking about. I
> actually ran the accumulative annual study. That's true that cumulative
> result shows you get less illuminace in more dense areas but what are
the
> cutting levels? Do we have the concept of over-daylit for outdoors?
>
> For example if I calculate the availability of useful daylight
illuminance
> based on 100 lux and 2500 lux for working hours and calculate the result
> based on the percentage of hours a large portion of the well-daylit
outdoor
> spaces will be considered as over-daylit because they receive more than
> 2500 lux, and then the more dark outdoor spaces located in Seattle or
> London (hi Rob!) will be assumed as well-daylit since they will be in
the
> range. We already knew this is not true and the spaces next to an
outdoor
> space with 150 lux horizontal illuminance level cannot be well-daylit.
>
> Maybe we can say there should be no upper-limit for outdoor illuminace
> level since we can always mitigate the light level by building envelope
> design, but what is the lower limit then?
>
> Best,
> Mostapha
>
> PS.1: I liked the concept of "warm shade" so much. So interesting to
think
> about.... Can you send me a link to the paper or any other resources?
>
>
> On Wed, Nov 30, 2011 at 10:26 AM, John Mardaljevic <[email protected]> >> wrote:
>
>> Hi Mostapha,
>>
>> > For an urban design study I wanted to avoid measuring light levels
>> inside the buildings as far as possible.
>>
>> How about using cumulative values, say annual or maybe monthly? You
>> could also look at just the hours of occupancy. Some examples here:
>>
>>
>> The image for London clearly shows the effect of tall buildings
reducing
>> the ground level cumulative illuminance (actually, irradiance in the
legend
>> but just x 100 to estimate klux-hrs / yr).
>>
>> Best
>> John
>>
>> Institute of Energy and Sustainable Development
>> De Montfort University, The Gateway, Leicester, LE1 9BH, UK
>> Tel: +44 (0) 116 257 7972
>>
>> [email protected]
>> http://www.iesd.dmu.ac.uk/~jm
>>
>>
>> _______________________________________________
>> [email protected]
>>
>
> _______________________________________________
> [email protected]
>
>
>
> _______________________________________________
> [email protected]
>
>
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