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[OL-Forum] Digest Number 1259
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There are 5 messages in this issue.
Topics in this digest:
1. Re: Re: exact answer on shielding and skyglow
From: kgfleming@att...
2. Re: Re: exact answer on shielding and skyglow
From: "Fabio Falchi" <fabio_falchi@yahoo...>
3. FCO/CO Performance Comparison
From: "Leo Smith" <leo@smith...>
4. Re: FCO/CO Performance Comparison
From: George Nickas <nickas@hanover...>
5. Re: FCO/CO Performance Comparison
From: "Fabio Falchi" <fabio_falchi@yahoo...>
________________________________________________________________________
________________________________________________________________________
Message: 1
Date: Sat, 05 Mar 2005 16:45:17 +0000
From: kgfleming@att...
Subject: Re: Re: exact answer on shielding and skyglow
-------------- Original message ----------------------
From: Jan Hollan <jhollan@amper....muni.cz>
>...As this is one of our main controversies with the lighting industry (they
> mostly claim the opposite), it's really important to prove that sky
> luminance almost nowhere increases several times due to snow, as it would,
> if the lit terrain would be dominant (it would be dominant in a completely
> FS-luminaires lit city)...
Jan,
A couple of years ago I gave a talk to the local IESNA chapter. It was a two part program and I followed a Lithonia sales rep who gave his take on the dark sky issue. I didn't know what to expect from him and he mostly dismissed dark sky concerns. One of his visual aids was a computer generated streetscape viewed from zenith of first a semi-cutoff streetlight array, then the same scene utilizing fco instead of sco. Surface luminance was clearly greater in the fco version. This he reasoned, demonstrates that sco creates less sky glow than fco.
The problem with his reasoning, of course, is that his images depicted surface brightness of the ground when viewed along a specific angle. Conceivably the images demonstrate that fco results in greater ground reflectance toward the zenith. That however, demonstrates nothing about the aggregate amount of ground reflectance at all angles above horizontal, all of which impacts upon sky glow.
After the meeting I asked him if I could get a copy of these images he used. He said they were from Lithonia and would have to check with them. I never was able to get them.
Kevin
________________________________________________________________________
________________________________________________________________________
Message: 2
Date: Sat, 5 Mar 2005 19:16:36 +0100
From: "Fabio Falchi" <fabio_falchi@yahoo...>
Subject: Re: Re: exact answer on shielding and skyglow
Really I don't understand the line of defence of the light producers (and
polluters).
It would be AGAINST their aim (sell fixtures) if the reflected light was the
most important in producing sky glow.
This is why:
We say that if we install only FS fixtures there will be a great beneficial
effect on the sky glow. So they can sell their fixtures (FS, of course).
They say that FS fixtures cause more pollution that SCO. This imply that, to
lower the sky luminance we MUST IMPOSE a generalized dimming of the existing
implants and, moreover, stop the installation of new fixtures!
Of course, this will be the way even if the FS politics will be adopted,
but, with a significative delay in time. Producer should resign themself
that the market cannot sustain an infinite exponential growth. They should
resign to a sostitution market, as the car producer learned time ago.
Clear skies,
Fabio Falchi
----- Original Message -----
From: <kgfleming@att...>
To: <OutdoorLighting-Forum@yahoogroups...>
Sent: Saturday, March 05, 2005 5:45 PM
Subject: Re: [OL-Forum] Re: exact answer on shielding and skyglow
>
> -------------- Original message ----------------------
> From: Jan Hollan <jhollan@amper....muni.cz>
>
>>...As this is one of our main controversies with the lighting industry
>>(they
>> mostly claim the opposite), it's really important to prove that sky
>> luminance almost nowhere increases several times due to snow, as it
>> would,
>> if the lit terrain would be dominant (it would be dominant in a
>> completely
>> FS-luminaires lit city)...
>
>
> Jan,
>
> A couple of years ago I gave a talk to the local IESNA chapter. It was a
> two part program and I followed a Lithonia sales rep who gave his take on
> the dark sky issue. I didn't know what to expect from him and he mostly
> dismissed dark sky concerns. One of his visual aids was a computer
> generated streetscape viewed from zenith of first a semi-cutoff
> streetlight array, then the same scene utilizing fco instead of sco.
> Surface luminance was clearly greater in the fco version. This he
> reasoned, demonstrates that sco creates less sky glow than fco.
>
> The problem with his reasoning, of course, is that his images depicted
> surface brightness of the ground when viewed along a specific angle.
> Conceivably the images demonstrate that fco results in greater ground
> reflectance toward the zenith. That however, demonstrates nothing about
> the aggregate amount of ground reflectance at all angles above horizontal,
> all of which impacts upon sky glow.
>
> After the meeting I asked him if I could get a copy of these images he
> used. He said they were from Lithonia and would have to check with them. I
> never was able to get them.
>
> Kevin
>
>
>
>
> OutdoorLighting-Forum - "The largest uncensored and most active forum on
> light pollution."
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________________________________________________________________________
________________________________________________________________________
Message: 3
Date: Sat, 5 Mar 2005 13:54:43 -0500
From: "Leo Smith" <leo@smith...>
Subject: FCO/CO Performance Comparison
The outdoor lighting manufacturers claim that if FCOs are used, more
fixtures will be required. Our state DOT does not use FCOs when an SCO burns
out, because of concern that the FCO will have a narrower cone of
illumination and will thereby disrupt the light distribution.
Recent research indicates this assumption not to be true. Additional
research studies on the performance of specific maufacturers FCOs would be
useful, especially countering the claim that more FCOs are required to light
an area.
I would appreciate any additional research information comparing the
performance of specific FCO makes and models to the performance of CO or SCO
fixtures.
Leo Smith
________________________________________________________________________
________________________________________________________________________
Message: 4
Date: Sat, 5 Mar 2005 14:03:34 -0500
From: George Nickas <nickas@hanover...>
Subject: Re: FCO/CO Performance Comparison
Getting old I guess--can somebody put FCO, SCO, CO in context for me
once again? I promise not to forget, and will even write it down.
Thanks.
gn
On Mar 5, 2005, at 1:54 PM, Leo Smith wrote:
>
> The outdoor lighting manufacturers claim that if FCOs are used, more
> fixtures will be required. Our state DOT does not use FCOs when an SCO
> burns
> out, because of concern that the FCO will have a narrower cone of
> illumination and will thereby disrupt the light distribution.
>
> Recent research indicates this assumption not to be true. Additional
> research studies on the performance of specific maufacturers FCOs
> would be
> useful, especially countering the claim that more FCOs are required to
> light
> an area.
>
> I would appreciate any additional research information comparing the
> performance of specific FCO makes and models to the performance of CO
> or SCO
> fixtures.
>
> Leo Smith
>
>
>
>
> OutdoorLighting-Forum - "The largest uncensored and most active forum
> on light pollution."
>
> Inbox out of reach? Choose "no email" at
> http://groups.yahoo.com/group/OutdoorLighting-Forum/join?referer=1
> and view posts in the archives,
> http://groups.yahoo.com/group/OutdoorLighting-Forum/messages - only on
> OLF.
> To join: OutdoorLighting-Forum-subscribe@yahoogroups...
> Unsubscribe from any Yahoo list: listname-unsubscribe@yahoogroups...
> =======================================================================
> =======
> No endorsement of content posted to OLF by any organization is implied.
> =======================================================================
> =======
> Yahoo! Groups Links
>
>
>
>
>
>
________________________________________________________________________
________________________________________________________________________
Message: 5
Date: Sun, 6 Mar 2005 10:13:03 +0100
From: "Fabio Falchi" <fabio_falchi@yahoo...>
Subject: Re: FCO/CO Performance Comparison
Avaiable for free is a light design software (Easy light-Save the sky:
http://www.vialattea.net/bonata/stskyen.htm) that can be downloaded with
3600 photometrical data form several manufacturer. All the data are of FS
fixtures and with them it is possible to obtain unbelievable performances,
like ratio distance/height of the poles of more than 5 (this with the more
stringent uniformity parameters required by European standard rules!).
You can add your own photometric data of SCO and compare them.
Try it!
Fabio Falchi
----- Original Message -----
From: "Leo Smith" <leo@smith...>
To: <OutdoorLighting-Forum@yahoogroups...>
Sent: Saturday, March 05, 2005 7:54 PM
Subject: [OL-Forum] FCO/CO Performance Comparison
>
> The outdoor lighting manufacturers claim that if FCOs are used, more
> fixtures will be required. Our state DOT does not use FCOs when an SCO
> burns
> out, because of concern that the FCO will have a narrower cone of
> illumination and will thereby disrupt the light distribution.
>
> Recent research indicates this assumption not to be true. Additional
> research studies on the performance of specific maufacturers FCOs would be
> useful, especially countering the claim that more FCOs are required to
> light
> an area.
>
> I would appreciate any additional research information comparing the
> performance of specific FCO makes and models to the performance of CO or
> SCO
> fixtures.
>
> Leo Smith
>
>
>
>
> OutdoorLighting-Forum - "The largest uncensored and most active forum on
> light pollution."
>
> Inbox out of reach? Choose "no email" at
> http://groups.yahoo.com/group/OutdoorLighting-Forum/join?referer=1
> and view posts in the archives,
> http://groups.yahoo.com/group/OutdoorLighting-Forum/messages - only on
> OLF.
> To join: OutdoorLighting-Forum-subscribe@yahoogroups...
> Unsubscribe from any Yahoo list: listname-unsubscribe@yahoogroups...
> ==============================================================================
> No endorsement of content posted to OLF by any organization is implied.
> ==============================================================================
> Yahoo! Groups Links
>
>
>
>
>
>
>
________________________________________________________________________
________________________________________________________________________
OutdoorLighting-Forum - "The largest uncensored and most active forum on light pollution."
Inbox out of reach? Choose "no email" at http://groups.yahoo.com/group/OutdoorLighting-Forum/join?referer=1
and view posts in the archives, http://groups.yahoo.com/group/OutdoorLighting-Forum/messages - only on OLF.
To join: OutdoorLighting-Forum-subscribe@yahoogroups...
Unsubscribe from any Yahoo list: listname-unsubscribe@yahoogroups...
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