# how to 1) simulate reflected solar radiation and 2) longwave radiation from heated surface

Hi David,

While it may be possible to do something like this through careful scene design & trickery, Radiance is not geared towards long-wave IR calculations and under normal conditions, reflectors cannot also serve as emitting surfaces. It is also tricky to separate components, such as distinguishing what came from building surfaces from the sky component. Again, there are ways to accomplish it, but it's an advanced task and there would definitely be some debugging involved.

Cheers,
-Greg

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From: David Davidson <this.is.david.davidson@gmail.com>
Subject: [Radiance-general] how to 1) simulate reflected solar radiation and 2) longwave radiation from heated surface
Date: January 17, 2015 12:57:50 AM PST

Dear list,

May I ask if Radiance can simulate the following:

1. the amount of solar radiation (both direct and diffuse) receivable for a given point that is reflected from a given nearby surface, e.g the amount of solar radiation at the centre of a 10x10 courtyard and 2m above ground that is reflected from the building surfaces facing the courtyard.

2. the amount of longwave radiation received on a given point contributed as a result of a nearby surface that are heated by the sun,

Thanks!

Hi David,

I can't think of anything off-hand that would suit your needs, but perhaps there are others on the list who will have suggestions.

Best of luck,
-Greg

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From: David Davidson <this.is.david.davidson@gmail.com>
Date: January 24, 2015 11:44:39 PM PST

Thank you very much, Greg! Can you suggest alternative approaches for this type of task, e.g. CFD software?

- D.

Greg Ward <gregoryjward@gmail.com>于2015年1月21日星期三写道：
Hi David,

While it may be possible to do something like this through careful scene design & trickery, Radiance is not geared towards long-wave IR calculations and under normal conditions, reflectors cannot also serve as emitting surfaces. It is also tricky to separate components, such as distinguishing what came from building surfaces from the sky component. Again, there are ways to accomplish it, but it's an advanced task and there would definitely be some debugging involved.

Cheers,
-Greg

From: David Davidson <this.is.david.davidson@gmail.com>
Subject: [Radiance-general] how to 1) simulate reflected solar radiation and 2) longwave radiation from heated surface
Date: January 17, 2015 12:57:50 AM PST

Dear list,

May I ask if Radiance can simulate the following:

1. the amount of solar radiation (both direct and diffuse) receivable for a given point that is reflected from a given nearby surface, e.g the amount of solar radiation at the centre of a 10x10 courtyard and 2m above ground that is reflected from the building surfaces facing the courtyard.

2. the amount of longwave radiation received on a given point contributed as a result of a nearby surface that are heated by the sun,

Thanks!

Hi David,

my 2cents: The long wave part sounds basically achievable by ESP-r. You would probably need to model the courtyard as "indoor" with a very transparent roof, however. Long wave exchange can be tracked in ESP-r with quite high detailing. Possibly, you could also answer the solar question with ESP-r (separating "reflection" from "direct/diffuse solar" is probably also tricky, if actually necessary and likely a question of designing a few "experiments"). I am not entirely sure, though, how detailed reflections in closed spaces are followed (they are, to some degree). You can couple ESP-r with Radiance and if your material properties are "solar" and not "visual", I would expect that you could get a very good idea of what is happening in your space of interest.

A CFD package may be the alternative approach. However, I am not aware of any specific package in which solar reflection may be handled sufficiently. Long wave exchange should be covered O.K. One other possible source of a modelling package I am aware of could be Physibel (Belgium). They have tools that may cover your requirements.

Best
Achim

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On Jan 21, 2015, at 5:51 AM, Greg Ward <gregoryjward@gmail.com> wrote:

Hi David,

While it may be possible to do something like this through careful scene design & trickery, Radiance is not geared towards long-wave IR calculations and under normal conditions, reflectors cannot also serve as emitting surfaces. It is also tricky to separate components, such as distinguishing what came from building surfaces from the sky component. Again, there are ways to accomplish it, but it's an advanced task and there would definitely be some debugging involved.

Cheers,
-Greg

From: David Davidson <this.is.david.davidson@gmail.com>
Subject: [Radiance-general] how to 1) simulate reflected solar radiation and 2) longwave radiation from heated surface
Date: January 17, 2015 12:57:50 AM PST

Dear list,

May I ask if Radiance can simulate the following:

1. the amount of solar radiation (both direct and diffuse) receivable for a given point that is reflected from a given nearby surface, e.g the amount of solar radiation at the centre of a 10x10 courtyard and 2m above ground that is reflected from the building surfaces facing the courtyard.

2. the amount of longwave radiation received on a given point contributed as a result of a nearby surface that are heated by the sun,

Thanks!

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