Houses with black roof? What is the purpose?

[johng]

Maybe its psychological but I always feel hotter wearing a black T-shirt or trousers in the sun.

[DinoSabanovic]

On 2/22/2017 at 8:19 PM, johng said:

Maybe its psychological but I always feel hotter wearing a black T-shirt or trousers in the sun.

Of course it's hotter. When I use black hat my brain wants to melt under and wearing white hat I have zero problem when combining with white t-shirt when walking under the Sun even if it's 36C.

I have also white car.

[grollies]

On 22/02/2017 at 6:19 PM, eyecatcher said:

I tried to research colour and its affects with sunlight a while ago and I have found no evidence at all to suggest  for example why cricketers and tennis player play in white....its tradition thats all.

 

Then there are the Arabs, wearing white...but equally the women moslty wear black.....dont they??

 

You will find no evidence to suggest a black roof is better than a white roof. if anything you will get a negligable amount of light reflection...heat...well sorry it doesn't say "oh dear I am going to struggle to get through here, its primrose cream" 

 

white is often used because its clean looking, bright  and town planners prefer uniformity.

 

but hey its the hot season now, why don't you try wearing a white shirt one day and a black shirt the next. anyone tells me they noticed a difference is in dreamland.

 

the criteria is the material composition. a corrugated steel roof will get very hot, a grass roof will never get hot, a polyester tea shirt will get very hot, a cotton tea will not

So why are solar panels black?

[johng]

So that they absorb more solar radiation ?  or because the crystals are a naturally dark colour ?

or that both go hand in hand  the colour is dark because it absorbs solar radiation ?

Edited February 24, 2017 by johng

[grollies]

On 22/02/2017 at 6:19 PM, eyecatcher said:

I tried to research colour and its affects with sunlight a while ago and I have found no evidence at all to suggest  for example why cricketers and tennis player play in white....its tradition thats all.

https://www.waterproofmag.com/back_issues/201007/black_white_roofing.php

 

"Chu cited research from the Lawrence Berkeley National Laboratory, which claimed that the effect of painting about 63 percent of the roofs white in 100 large cities would provide about the same climate benefits as taking all the world's cars off the road for 10 years."

 

Quote

 

Then there are the Arabs, wearing white...but equally the women moslty wear black.....dont they??

Stops the women going outdoors for too long?

Edited February 24, 2017 by grollies

[eyecatcher]

8 hours ago, grollies said:

So why are solar panels black?

Ok...for your amusement just google "what colour are solar panels"

 

Go to images and you will see a psychedelic array of colours of the translucent glass they use.

 

Why not just google solar panels and look at the pagr after page of blue looking panels.

 

Essentially solar panels are as ugly as having a wind farm in the back yard. Seriously they have to be the most unsightly addition to a house.

Sadly the colour matching the roof tile or the grey sky doesnt get away from the fact that whatever you save in energy costs...you lose 10times more off the value of your property.

Its gotta be the most unwelcome addition to a property....period.

[grollies]

8 hours ago, johng said:

So that they absorb more solar radiation ?  or because the crystals are a naturally dark colour ?

or that both go hand in hand  the colour is dark because it absorbs solar radiation ?

As would a black roof perchance?

[johng]

Essentially solar panels are as ugly as having a wind farm in the back yard.

If you don't want yours you can donate them to me

[eyecatcher]

13 minutes ago, grollies said:

As would a black roof perchance?

I do likr the women going outdoors theory.......

......maybe its not a theory

 

Its the reason women have smaller feet also.....so they can get nearer the sink..the cooker...etc

[eyecatcher]

13 minutes ago, johng said:

If you don't want yours you can donate them to me

I only have the one and its on my head.

Even that one is ugly so the wife calls it a helicopter landing pad instead.

[DinoSabanovic]

A white roof is painted with solar reflective white coating and reflects up to 90% of sunlight (as opposed to traditional black roofs which reflect only 20%). A white roofs are a lot more than just white paint! White roofs' benefits are measured partly according to the solar reflectance index, or SRI. A roof's SRI is a measure of a surface's ability to reflect solar heat. SRI measures reflectance (reflecting the sun's rays) and thermal emittance (the roof's ability to radiate absorbed heat). If you've ever worn a black t-shirt in the sun than you already understand that black's reflectance is negligible and its emittance is zero. A white roof's reflectance is as high as 90% and its emittance is 100%.

[kovaltech]

20 hours ago, DinoSabanovic said:

A white roof is painted with solar reflective white coating and reflects up to 90% of sunlight (as opposed to traditional black roofs which reflect only 20%). A white roofs are a lot more than just white paint! White roofs' benefits are measured partly according to the solar reflectance index, or SRI. A roof's SRI is a measure of a surface's ability to reflect solar heat. SRI measures reflectance (reflecting the sun's rays) and thermal emittance (the roof's ability to radiate absorbed heat). If you've ever worn a black t-shirt in the sun than you already understand that black's reflectance is negligible and its emittance is zero. A white roof's reflectance is as high as 90% and its emittance is 100%.

congrats... almost 100% utterly nonsense...

 

The best heat retainer or heat shield is....: aluminium foil... ( rescue blankets to retain the heat for victims ? )

 

If perfect black absorbs 100%

then perfect white absorbs 10% and aluminium 0,1 %

 

same time perfect black radiates 99%

perfect white 9,9%

aluminium 0,09%

 

I think my number are far more correct then yours... 

 

"A white roof's reflectance is as high as 90% and its emittance is 100%"

if this where true then: your house would cool itself , no need for aircon anymore...

[DinoSabanovic]

It's from website : http://www.whiteroofproject.org/faq

And read what you wrote.

I wrote " white coating ... reflects up to 90% of sunlight" and you " then perfect white absorbs 10%"

Don't you think this is the same?

[kovaltech]

46 minutes ago, DinoSabanovic said:

It's from website : http://www.whiteroofproject.org/faq

And read what you wrote.

I wrote " white coating ... reflects up to 90% of sunlight" and you " then perfect white absorbs 10%"

Don't you think this is the same?

its about the whole sentence you used, not about a single word...

 

you did not wrote " white coating ... reflects up to 90% of sunlight"

 

but:

 

"A white roof's reflectance is as high as 90% and its emittance is 100%"

 

Its not the intent, but what people understand from your wording...

 

[DinoSabanovic]

On 3/1/2017 at 9:41 AM, kovaltech said:

its about the whole sentence you used, not about a single word...

 

you did not wrote " white coating ... reflects up to 90% of sunlight"

 

but:

 

"A white roof's reflectance is as high as 90% and its emittance is 100%"

 

Its not the intent, but what people understand from your wording...

 

Right. But... As I said before it's a copy/paste.

And second, English is not my native language and I don't have the time to check every single word is it spelled correctly.

That being said, don't you think reader should have some flexibility and read between the lines when reading forums?

 

This just proves my point that black color should not be used on places exposed to the Sun in tropical country's. 

[kovaltech]

1 hour ago, DinoSabanovic said:

Right. But... As I said before it's a copy/paste.

And second, English is not my native language and I don't have the time to check every single word is it spelled correctly.

That being said, don't you think reader should have some flexibility and read between the lines when reading forums?

 

This just proves my point that black color should not be used on places exposed to the Sun in tropical country's. 

English is not my native language either, but my data is still correct and in context.

 

If you understand why Touareg uses dark clothes in full sun, then you'l understand what the positive effect for a roof could be... (or actually is ) 

[Kwasaki]

Now then,  what is the purpose of black roofs girls. 

 

Just a thought it might be the planning dept, down our soi we had to have blue.