I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

In article ,
Guy Dawson writes:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

I would start by making sure your loft insulation is up to spec.
That helps summer and winter.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Andrew Gabriel wrote:
In article ,
Guy Dawson writes:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

I would start by making sure your loft insulation is up to spec.
That helps summer and winter.

Already done.

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.


I want to paint all my trees white. Is this what god invented bird**** for?

Guy Dawson wrote:
Andrew Gabriel wrote:
In article ,
Guy Dawson writes:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

I would start by making sure your loft insulation is up to spec.
That helps summer and winter.

Already done.

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

You need insulation between the rafters if you want the loft cool in
summer.

Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy

Whitewash is traditional. Its basically chalk in glue, and gradually
washes off in winter. If you want it to last longer then diluted lime
putty, but it needs 2 or 3 coats. In principle you could use masonry
paint, but then you'd have to actually get up there and make sure
there was no splash or overpaint. The lime paints thats not a problem
with, any spill is just hosed off, and a floor brush can be used for
painting.


NT

Stuart Noble wrote:

You need insulation between the rafters if you want the loft cool in
summer.

It's not so much the keeping the loft cool but the reflection of sunlight
back into space to avoid heating the atmosphere.

Prof Chu's point is that a lot of solar heating is caused by building
being heated by the sun and radiating the heat back into the atmosphere.

If the sunlight could be reflected back into space by white surfaces then
we'd help slow global warming.

http://www.climateark.org/shared/rea...?linkid=128556


Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd

Guy Dawson wrote:
Stuart Noble wrote:

You need insulation between the rafters if you want the loft cool in
summer.

It's not so much the keeping the loft cool but the reflection of sunlight
back into space to avoid heating the atmosphere.

Prof Chu's point is that a lot of solar heating is caused by building
being heated by the sun and radiating the heat back into the atmosphere.

If the sunlight could be reflected back into space by white surfaces then
we'd help slow global warming.

http://www.climateark.org/shared/rea...?linkid=128556


Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd


White tarmac too maybe.

Stuart Noble wrote:

White tarmac too maybe.

That's also suggested!

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd

Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

On 28 May, 08:02, Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

Extensive green roof (or brown roof) is better.

Admittedly a bit hard to retrofit to a 45° slope, but it's what I'm
doing with my sheds (which are 3× the house roof area).

In article ,
"Fredxx" writes:

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

White is a definition which relates to visible light.
I suspect far more energy is present in the infrared,
and it's more important that it's reflective in the
infrared than the visible. Sheet copper would probably
be quite good if it didn't tarnish, or some type of
plasticised film version. At a former workplace, we
had the roof painted to reduce solar gain, and IIRC,
the paint looked green.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Dave Osborne wrote:

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

hang head in shame
Oh yeah!
/hang head in shame

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd

Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N 986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4 4.45.4

Surely we should be trying to collect this energy and substitute it for
fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?

Don

Donwill wrote:

Surely we should be trying to collect this energy and substitute it for
fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?

Indeed. However the systems are quite expensive still.

Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

"Andrew Gabriel" wrote in message
...
In article ,
"Fredxx" writes:

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N
986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4
4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

White is a definition which relates to visible light.
I suspect far more energy is present in the infrared,
and it's more important that it's reflective in the
infrared than the visible. Sheet copper would probably
be quite good if it didn't tarnish, or some type of
plasticised film version. At a former workplace, we
had the roof painted to reduce solar gain, and IIRC,
the paint looked green.


It's not a coincidence that the suns energy is concentrated in the visible
spectrum. The peak is in fact at green.

Reflecting the near infrared is a complete waste of time, it is generally
not transmitted through the atmosphere, and if we do manage to reflect the
re-radiated near infrared energy, it would only be absorbed again by the
atmosphere. Infrared reflecting paints are next to useless.

"Fredxx" wrote in message
...

"Andrew Gabriel" wrote in message
...
In article ,
"Fredxx" writes:

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help
combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey
concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N
986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4
4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

White is a definition which relates to visible light.
I suspect far more energy is present in the infrared,
and it's more important that it's reflective in the
infrared than the visible. Sheet copper would probably
be quite good if it didn't tarnish, or some type of
plasticised film version. At a former workplace, we
had the roof painted to reduce solar gain, and IIRC,
the paint looked green.


It's not a coincidence that the suns energy is concentrated in the visible
spectrum. The peak is in fact at green.

Reflecting the near infrared is a complete waste of time, it is generally
not transmitted through the atmosphere, and if we do manage to reflect the
re-radiated near infrared energy, it would only be absorbed again by the
atmosphere. Infrared reflecting paints are next to useless.


Indeed, the greenhouse effect works because visible/uv energy comes from the
sun through the atmosphere (or greenhouse glass) (mostly) and is absorbed by
the earth and re-radiated as infra-red, which the atmosphere (or green-house
glass) doesn't let out again (mostly). So white or silver reflectors would
work best in terms of cooling the earth.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not)

On Thu, 28 May 2009 11:05:49 GMT, Stuart Noble wrote:

Guy Dawson wrote:
Stuart Noble wrote:

You need insulation between the rafters if you want the loft cool in
summer.

It's not so much the keeping the loft cool but the reflection of sunlight
back into space to avoid heating the atmosphere.

Prof Chu's point is that a lot of solar heating is caused by building
being heated by the sun and radiating the heat back into the atmosphere.

If the sunlight could be reflected back into space by white surfaces then
we'd help slow global warming.

http://www.climateark.org/shared/rea...?linkid=128556

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd


White tarmac too maybe.

With black lines?
--
Peter.
You don't understand Newton's Third Law of Motion?
It's not rocket science, you know.

Guy Dawson wrote:
Donwill wrote:

Surely we should be trying to collect this energy and substitute it
for fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?

Indeed. However the systems are quite expensive still.
Expensive to who? yourself? The planet? The planet wont care one way or
another, it will survive. However the human species that has inflicted
itself on the other species which inhabit this planet will probably
destroy itself competing for resources. We have the ability and
arrogance to reckognise when other species need culling, yet we are
blind to our own faults and untrammelled ambitions.

Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

I suggest you go and read James Lovelock's "The Vanishing Face of Gaia"
that could be useful to you.

Don

Guy Dawson wrote:
Donwill wrote:

Surely we should be trying to collect this energy and substitute it for
fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?

Indeed. However the systems are quite expensive still.

Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

solar warm air heating can be installed for hundreds of pounds, and
pays back ok if sufficiently well designed.


NT

Donwill wrote:
Guy Dawson wrote:
Donwill wrote:

Surely we should be trying to collect this energy and substitute it
for fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?

Indeed. However the systems are quite expensive still.

Expensive to who? yourself?

Me of course.

The planet? The planet wont care one way or another, it will survive.

Indeed. The planet will be fine. It coped with the 7C rise in 50years at
the end the last ice age - I think I read that in the book Six Degrees - and
the plant will cope in some way with what ever we throw at it.

However the human species that has inflicted
itself on the other species which inhabit this planet will probably
destroy itself competing for resources. We have the ability and
arrogance to reckognise when other species need culling, yet we are
blind to our own faults and untrammelled ambitions.

So it's not worth us doing anything?


Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

I suggest you go and read James Lovelock's "The Vanishing Face of Gaia"
that could be useful to you.

If you're in a sinking boat do you wait to drown or start bailing and
look for a plan B?

Guy

Guy Dawson wrote:
Donwill wrote:
Guy Dawson wrote:
Donwill wrote:

Surely we should be trying to collect this energy and substitute it
for fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?

Indeed. However the systems are quite expensive still.

Expensive to who? yourself?

Me of course.

The planet? The planet wont care one way or another, it will survive.

Indeed. The planet will be fine. It coped with the 7C rise in 50years at
the end the last ice age - I think I read that in the book Six Degrees -
and
the plant will cope in some way with what ever we throw at it.

However the human species that has inflicted itself on the other
species which inhabit this planet will probably destroy itself
competing for resources. We have the ability and arrogance to
reckognise when other species need culling, yet we are blind to our
own faults and untrammelled ambitions.

So it's not worth us doing anything?


Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

I suggest you go and read James Lovelock's "The Vanishing Face of
Gaia" that could be useful to you.

If you're in a sinking boat do you wait to drown or start bailing and
look for a plan B?

Guy
Unfortunately the boat is already many metres below the surface because
of the inertia in the system.

Don

Guy
Unfortunately the boat is already many metres below the surface
because of the inertia in the system.


I cannot find the energy involved in sourcing, transporting and applying
reflective paint. Nor the opportunity cost of spending money on that
rather than other options. I can specialist paints make sense where the
energy would otherwise be removed by conventional air conditioning but
for those of us who just pant.....?

In passing, anyone offering odds on the North Koreans arguing that their
nuclear programme is geared to solving global warming by carefully
applied doses of nuclear winter?

--
R

Donwill wrote:

Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

I suggest you go and read James Lovelock's "The Vanishing Face of
Gaia" that could be useful to you.

If you're in a sinking boat do you wait to drown or start bailing and
look for a plan B?

Guy
Unfortunately the boat is already many metres below the surface because
of the inertia in the system.

So it's not worth trying to swim up towards the surface?

Guy

On Thu, 28 May 2009 17:07:44 +0100, wrote:

On Thu, 28 May 2009 13:57:15 +0100, PeterC
wrote:

On Thu, 28 May 2009 11:05:49 GMT, Stuart Noble wrote:

Guy Dawson wrote:
Stuart Noble wrote:


If the sunlight could be reflected back into space by white surfaces then
we'd help slow global warming.

http://www.climateark.org/shared/rea...?linkid=128556

Guy
-- --------------------------------------------------------------------
Guy Dawson I.T. Manager Crossflight Ltd


White tarmac too maybe.

With black lines?

A negative point against the idea would be having to repaint all the
Zebra crossings.

G.Harman

yeah - white and black.
--
Peter.
You don't understand Newton's Third Law of Motion?
It's not rocket science, you know.

Stuart Noble wrote:
Guy Dawson wrote:
Stuart Noble wrote:

You need insulation between the rafters if you want the loft cool in
summer.

It's not so much the keeping the loft cool but the reflection of
sunlight back into space to avoid heating the atmosphere.

Prof Chu's point is that a lot of solar heating is caused by building
being heated by the sun and radiating the heat back into the
atmosphere. If the sunlight could be reflected back into space by white
surfaces
then we'd help slow global warming.


White tarmac too maybe.

HTF are you going to keep that clean? :-)


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

In message , Bob Mannix
writes
"Fredxx" wrote in message
...

"Andrew Gabriel" wrote in message
...
In article ,
"Fredxx" writes:

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help
combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey
concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N
986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4
4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

White is a definition which relates to visible light.
I suspect far more energy is present in the infrared,
and it's more important that it's reflective in the
infrared than the visible. Sheet copper would probably
be quite good if it didn't tarnish, or some type of
plasticised film version. At a former workplace, we
had the roof painted to reduce solar gain, and IIRC,
the paint looked green.


It's not a coincidence that the suns energy is concentrated in the visible
spectrum. The peak is in fact at green.

Reflecting the near infrared is a complete waste of time, it is generally
not transmitted through the atmosphere, and if we do manage to reflect the
re-radiated near infrared energy, it would only be absorbed again by the
atmosphere. Infrared reflecting paints are next to useless.


Indeed, the greenhouse effect works because visible/uv energy comes from the
sun through the atmosphere (or greenhouse glass) (mostly) and is absorbed by
the earth and re-radiated as infra-red, which the atmosphere (or green-house
glass) doesn't let out again (mostly). So white or silver reflectors would
work best in terms of cooling the earth.

Now, where have all those old CDs gone ?

--
geoff

"Guy Dawson" wrote in message
...
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Cover it with aluminium foil - more reflective and it will keep the Martian
mind control rays out too.

Colin Bignell

wrote:
Guy Dawson wrote:
Donwill wrote:

Surely we should be trying to collect this energy and substitute it for
fossil fuels rather than attempt to reflect it back through our
atmosphere to space. I think that makes more sense don't you?
Indeed. However the systems are quite expensive still.

Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

solar warm air heating can be installed for hundreds of pounds, and
pays back ok if sufficiently well designed.


NT
Bwahahah

In the Mojave desert maybe. Not in e.g.Accrington...

On Thu, 28 May 2009 15:22:06 +0100, Guy Dawson wrote:
If you're in a sinking boat do you wait to drown or start bailing and
look for a plan B?

The trick is presumably to not be so busy bailing that you miss plan B
altogether

On Thu, 28 May 2009 09:33:59 +0100, The Natural Philosopher wrote:

Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey concrete
tiles on it. It sure does get hot in the loft during the summer.


I want to paint all my trees white. Is this what god invented bird**** for?

Hmm, so I'm already doing my bit by having so many silver birch?

Guy Dawson wrote:
Donwill wrote:

Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

Guy

I suggest you go and read James Lovelock's "The Vanishing Face of
Gaia" that could be useful to you.

If you're in a sinking boat do you wait to drown or start bailing and
look for a plan B?

Guy
Unfortunately the boat is already many metres below the surface
because of the inertia in the system.

So it's not worth trying to swim up towards the surface?

Hope springs eternal..............

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember Guy Dawson
saying something like:

I see that Prof Chu says we should paint our roofs white to help combat
climate change.

Paint your bottom blue and have done with it.
I'm sure that would be as much use.

"Guy Dawson" wrote in message
...


So it's not worth us doing anything?

Not if saving the planet is your goal.


What people appear to forget is that we are in an ice age and the normal
climate of the Earth is about 15C higher than it is now.

It goes much colder too.
We just happen to have evolved during one of the bits in-between.

"Guy Dawson" wrote in message
...
....
Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

However, painting our roofs white is not doing something useful. We would
need to cover a lot more of the planet with cities before their colour
became significant.

Colin Bignell.

"Owain" wrote in message
...
Fredxx wrote:
It's not a coincidence that the suns energy is concentrated in the
visible spectrum. The peak is in fact at green.

Don't you mean it's not a coincidence that our visual receptors are
optimised to the sun's peak output?


I thought that's what I said? Visible impies our visual receptors have a
sensitivity.

"nightjar .me.uk" cpb@insert my surname here wrote in message
...

"Guy Dawson" wrote in message
...
...
Rather than doing nothing and waiting for the perfect solution we can
still do something useful...

However, painting our roofs white is not doing something useful. We would
need to cover a lot more of the planet with cities before their colour
became significant.


I don't know, but at the same time, I haven't seen any figures which relate
a Kg of CO2 to KW of atmospheric heat retention.

Given than the sun's energy falling on a roof top is around 1KW, a white
roof can contribute a significant return of sunlight back into space, and
potential cooling of the ground and consequently, the atmosphere.

On Thu, 28 May 2009 13:53:55 +0100, "Bob Mannix"
wrote:

"Fredxx" wrote in message
...

"Andrew Gabriel" wrote in message
...
In article ,
"Fredxx" writes:

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help
combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey
concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N
986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4
4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

White is a definition which relates to visible light.
I suspect far more energy is present in the infrared,
and it's more important that it's reflective in the
infrared than the visible. Sheet copper would probably
be quite good if it didn't tarnish, or some type of
plasticised film version. At a former workplace, we
had the roof painted to reduce solar gain, and IIRC,
the paint looked green.


It's not a coincidence that the suns energy is concentrated in the visible
spectrum. The peak is in fact at green.

Reflecting the near infrared is a complete waste of time, it is generally
not transmitted through the atmosphere, and if we do manage to reflect the
re-radiated near infrared energy, it would only be absorbed again by the
atmosphere. Infrared reflecting paints are next to useless.


Indeed, the greenhouse effect works because visible/uv energy comes from the
sun through the atmosphere (or greenhouse glass) (mostly) and is absorbed by
the earth and re-radiated as infra-red, which the atmosphere (or green-house
glass) doesn't let out again (mostly). So white or silver reflectors would
work best in terms of cooling the earth.

I thought that the painting roofs white theory had been debunked? I
guess Prof Chu has shares in Dulux.

--
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(='.'=) Owing to the amount of spam posted via googlegroups and
(")_(") their inaction to the problem. I am blocking most articles
posted from there. If you wish your postings to be seen by
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"Mark" wrote in message
...
On Thu, 28 May 2009 13:53:55 +0100, "Bob Mannix"
wrote:

"Fredxx" wrote in message
...

"Andrew Gabriel" wrote in message
...
In article ,
"Fredxx" writes:

"Dave Osborne" wrote in message
...
Guy Dawson wrote:
I see that Prof Chu says we should paint our roofs white to help
combat
climate change.

We have a 1930s semi with a normal pitches roof with dark grey
concrete
tiles on it. It sure does get hot in the loft during the summer.

Any recommendations as to what I can use to paint (I assume) the
tiles
white?

Guy
-- ---------------------------------------------------------------------
Guy Dawson@SMTP - // ICBM - 6.15.16W 57.12.23N
986M
4.45.4 4.45.4 4.45.4 The Reality Check's in the Post! 4.45.4
4.45.4

Well, you could try googling for "roof tile paint"

e.g. http://www.nwepaints.co.uk/acatalog/...nCoatings.html

or even "solar reflective paint"

e.g. http://www.paco-systems.co.uk/pdfs/solarref.pdf

I'm always wary of solar reflective paints which are a grey.

For good reflectivity, they ought to at least start out white.

White is a definition which relates to visible light.
I suspect far more energy is present in the infrared,
and it's more important that it's reflective in the
infrared than the visible. Sheet copper would probably
be quite good if it didn't tarnish, or some type of
plasticised film version. At a former workplace, we
had the roof painted to reduce solar gain, and IIRC,
the paint looked green.


It's not a coincidence that the suns energy is concentrated in the
visible
spectrum. The peak is in fact at green.

Reflecting the near infrared is a complete waste of time, it is
generally
not transmitted through the atmosphere, and if we do manage to reflect
the
re-radiated near infrared energy, it would only be absorbed again by the
atmosphere. Infrared reflecting paints are next to useless.


Indeed, the greenhouse effect works because visible/uv energy comes from
the
sun through the atmosphere (or greenhouse glass) (mostly) and is absorbed
by
the earth and re-radiated as infra-red, which the atmosphere (or
green-house
glass) doesn't let out again (mostly). So white or silver reflectors would
work best in terms of cooling the earth.

I thought that the painting roofs white theory had been debunked? I
guess Prof Chu has shares in Dulux.


Oh I wasn't supporting his theory in general - there aren't enough roofs
but, if there were, I was commenting on the principle of white rather than
dark, which is correct.


--
Bob Mannix
(anti-spam is as easy as 1-2-3 - not