Talk:Reflective surfaces (climate engineering)

Untitled

Taken pretty much directly from the reference.

Planet cooling

I have doubts about this recent addition to the end of the lead: "provided that the materials used not only reflect solar energy, but also emit infra-red radiation to cool the planet." Certainly, it's a good thing if it emits thermal IR, but the way that's phrased makes it sounds like that's the only way it could help reduce global warming. A broadband low-emissivity surface would still help, and perhaps even have most of the benefit of an ideal low-e roof material. Am I missing something? And is there a reference for this?Ccrrccrr (talk) 04:39, 6 January 2009 (UTC)

There is a technology that only emits IR at a selected IR window, that being the 8 to 13um Atmosphere to space window, the same window that C02 is suppose to be blocking and causing global warming. The technology is know as SkyCool, it is capable of extracting heat out of a building via its spectraly selective emittance. I have seen buildings in very hot climates where the internal temperature is up to 8 degrees C below the external shade temperature. This technology passively cools the building without any electricity consumption. Usually large metal roofed buildings use it because the steel roof will easily become double the ambient shade temperature, however with Skycool applied it will only reach ambient and the sub roof temperature will be below ambient, infact it performs better without subroof insulation, as this slows the rate at which the heat can be conducted through the coating and then emitted to the upper atmosphere. —Preceding unsigned comment added by 203.217.18.179 (talk) 05:26, 4 June 2009 (UTC)

Silly Picture

Not a single roof is visible. A bullet point list would be just as informative. —Preceding unsigned comment added by 192.38.4.206 (talk) 15:49, 28 July 2009 (UTC)

Agree it is useless. Poor legibility combined with a gratuitous "illustration" which illustrates nothing. A list or chart would at least have the ability to rank the options.--75.164.155.194 (talk) —Preceding undated comment added 01:57, 25 August 2016 (UTC)

White Roofs Catch On as Energy Cost Cutters

• nytimes.com/2009/07/30/science/earth/30degrees.html?_r=1&em

White Roofs Catch On as Energy Cost Cutters

By FELICITY BARRINGER

NY Times: July 29, 2009

"In an experiment, the National Laboratory in Oak Ridge, Tenn., had two kinds of terra-cotta-colored cement tiles from American Rooftile installed on four new homes at the Fort Irwin Army base in California. One kind was covered with a special paint and reflected 45 percent of the sun’s rays — nearly twice as much as the other kind. The two homes with roofs of highly reflective paint used 35 percent less electricity last summer than the two with less reflective paint." -96.237.13.44 (talk) 01:55, 31 July 2009 (UTC)

Converting between centigrade and Fahrenheit for temperature differences

This statement "In the heat of the full sun, the surface of a black roof can increase in temperature as much as 50 °C (90 °F)" has been changed a couple of times in the last few minutes to read "In the heat of the full sun, the surface of a black roof can increase in temperature as much as 50 °C (122 °F)". 90 °F is correct because it is a temperature difference (an increase in temperature), and in taking the difference the 32° that normally would be part of the conversion gets canceled out. Here is the algebra. If C₂ - C₁ = 50 °C, where C₁ and C₂ are temperatures in degrees centigrade, and F₁ and F₂ are the corresponding temperatures in Fahrenheit, then F₁ = 9/5 * C₁ + 32 and F₂ = 9/5 * C₂ + 32. Then F₂ - F₁ = (9/5*C₂ + 32) - (9/5*C₁ + 32) = 9/5*(C₂ - C₁) + (32-32) = 9/5*(50) + 0 = 90 °F. Susfele (talk) 04:38, 2 September 2010 (UTC)

Actually the only correct way to measure temperature differences is in kelvin.77.13.246.125 (talk) 23:39, 18 September 2016 (UTC)

Disadvantages of Cool Roofs

This section is pretty hard to follow. Basically the study cited concluded that, considering Albedo only, then net effect of global conversion to white rooves was a slight temperature *increase*, due to secondary effects such as changes in wind and cloud cover. However this study did not take into account the effects of any reduced energy use and greenhouse gas emissions due to cool roofs.

I suggest rewording the paragraph as follows: "While the perceived benefits are enormous, a 2011 study suggested that although a reflecting roof will decrease temperatures in a single house, and also reduce the "heat island effect", these may actually contribute to a raised global temperature due to the effect on cloud cover and other weather patterns. This study, however, only considered the albedo (light reflection) effect of white roofs, and did not take into account lower energy use and emission creation that would result from less energy needed for cooling houses having white roofs." --Tombleyboo (talk) 22:03, 16 May 2012 (UTC)

Disadvantages...

Why is "A subsequent 2012 study by researchers at Concordia University..." in the DISadvantages section? Offsetting 150 gigatonnes of carbon dioxide is a GOOD thing. 71.139.164.10 (talk) 00:36, 29 August 2012 (UTC)

Because it is a refutation of the initial finding. This article is more the discussion of a topic than a factual resource. — Preceding unsigned comment added by 75.164.155.194 (talk) 01:51, 25 August 2016 (UTC)

Tropical roof

Wikipedia should at least mention a tropical roof. its just a second layer of iron (or perhaps solar panels!), providing a ventilated gap between the original roof and the heated surface. Charlieb000 (talk) 10:17, 25 February 2013 (UTC)

More images

I think the use of more images would help the page be clearer to the readers. KTakenak (talk) 15:46, 9 September 2014 (UTC)

The one image is noncontributory. Yes, there is a need for some diagrams here.--75.164.155.194 (talk) 01:59, 25 August 2016 (UTC)

More about reflective roads etc.

This article seems to be almost entirely about cool roofs rather than other surfaces; e.g. roads, and maybe other ground surfaces (e.g. I think planting more grass has been proposed).

So I suggest either more about these are added to this article, or this article is renamed Cool roofs and a separate article created for reflective roads etc.

Incidentally the word 'pavement' seems to be used in this article meaning road surface, whereas in the UK pavement means US sidewalk. I suggest a universal term is used (e.g. 'road' or 'road surface'?) Ben Finn (talk) 14:15, 24 June 2015 (UTC)

Benefits of cool roofs

This sentence doesn't make much sense:

A 2012 study by researchers at Concordia University included variables similar to those used in the Stanford study (e.g., cloud responses) and estimated that worldwide deployment of cool roofs and pavements in cities would generate a global cooling effect equivalent to offsetting up to 150 gigatonnes of carbon dioxide emissions – enough to take every car in the world off the road for 50 years.[14][15]

First, the units are incorrect. Replacing roofs and pavements with "cool" materials will reduce carbon dioxide emissions by a certain amount each year. This benefit would continue every year. Therefore the benefit needs to be stated as a rate, not an amount (Currently stated as 50 years of car carbon emissions; yes this is an amount not a rate.)

Second, the verbiage "global cooling effect" is misleading. It will prevent any amount of global warming that would be caused by the prevented carbon emissions, but it will not reverse previous emissions. I feel misunderstanding could be especially occur with this topic, because the "cool" materials will help cool a local area by reflecting, but globally the reflection impact is minimal, except for the prevention of carbon emissions caused by AC units, etc.

Quicknick5k (talk) 05:38, 25 November 2016 (UTC)quicknick5k

Indeed. Is this saying that one year of all roofs and pavement in the world being replaced would be equivalent to 50 years of no cars? I read the paper and it still doesn't make sense - when climate scientists give units of mass of CO2 do they mean per year? Maybe someone more familiar with that field could clarify this. Dakane2 (talk) 21:08, 9 October 2017 (UTC)

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Mirrors in agriculture, on desserts and oceans.

in agriculture it may have benefits of keeping humidity and protecting plants from heat. In desserts and oceans - just cooling earth. MEER: reflection project of Dr Ye Tao is all about that. (I was surprised, that the article on surfaces is almost entirely on roofs. Roofs deserve their own article and title in my opinion). 31.0.85.139 (talk) 23:41, 18 March 2022 (UTC)