Comments for Jason Underdown's Blog

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by Peter Kaminsky

Peter Kaminsky — Mon, 30 Nov 2009 04:12:16 +0000

I absolutely agree with Jason's views. But i think the reason behind painting the flat roofs white is that slanted roofs are oriented at a certain angle w.r.t. to the horizontal axis which minimizes the amount of heat that can be reflected, compared to the flat roofs. One more thing, Considering to the Science literacy rate in our country, it is indeed a disappointing fact for us that countries like India and China have a great amount of science literacy compared to us and this makes them much more superior. By the way, i came across these excellentphysics flash cards. Its also a great initiative by the FunnelBrain team. Amazing!!!

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by rorroyaphyBup

rorroyaphyBup — Wed, 25 Nov 2009 18:57:36 +0000

Awesome, I didn’t know about that until now. Thx!

Comment on Creating Printable PDF Flash Cards Using LaTeX by Jason Underdown

Jason Underdown — Wed, 25 Nov 2009 01:01:50 +0000

I would not say that I am giving up on them, but I have no immediate plans to update them in the near future. However, I plan to be a college math professor, and will certainly use them in my classes in the future.

The LaTeX source code is available, so feel free to download that and change or add to them as much as you please. If you post new sets on your web site, please link back to me.

Comment on Creating Printable PDF Flash Cards Using LaTeX by Rafael

Rafael — Wed, 25 Nov 2009 00:26:11 +0000

Are you going to finish the flashcards available on you page or you gave up on them?

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by wookiemeister

wookiemeister — Tue, 25 Aug 2009 10:15:33 +0000

ok….a quick explanation of why white paint works to cool the planet……

1 around 50 percent of sunlight is visible light

2 around 50 percent of sunlight is heat (infra red – i will call it heat for the moment)

3 visible light is a frequency of light NOT absorbed by the atmosphere. repeat not absorbed by the atmosphere in practical terms.

4 some HEAT (infra red) from the sun IS absorbed by the atmosphere directly (greenhouse gasses which makes the atmosphere warmer).

5 HEAT from the sun also warms the surface of the planet and this HEAT is then radiated back into the atmosphere again being absorbed by greenhouse gasses.

6 visible light is poorly absorbed by the atmosphere/ greeenhouse gasses, some of it gets reflected back by the atmosphere.

7 the visible light that doesn’t get reflected back by the atmosphere is either reflected by the surface (eg a snow field) or absorbed by the surface (an asphalt carpark/ road). this absorbed light heats the dark surface. this heat is then radiated into the atmosphere and is absorbed by greenhouses gasses making the atmosphere warmer.

8 by painting your roof white and other surface you reflect around 50 percent of the visible energy from the sun, a significant amount of this is reflected back into space WITHOUT heating the atmosphere.

9 by painting enough roofs you make buildings cooler and cool the atmosphere. air conditioning works easier to cool houses because they are cooler, perhaps you wouldn’t even need air conditioning?

if you are thinking of using white paint to cool your roof you will need a special white insulative paint that both reflects the visible frequencies of light and stops infra red frequencies from heating your roof.

the special paint (something like insultec a waterbased white insulatiove paint) does two functions it reflects half of the suns energy and the insulative properties makes conduction and radiation of energy into your roof space is significantly reduced.

my house already has a pale cream colour to it but given a bit more time i will probably paint my roof and walls facing the sun sometime this summer (i australia it gets very hot here in summer)

chu is making the assumption that a cooler roof and building will mean less energy used to remove heat from the building, he’s right. its good to see the americans are finally waking up about how to use energy efficiently. over here in australia many people have foolishly bought houses with dark roofs. i can only hope that the american influence will convince them to change their thinking.

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by ritublog

ritublog — Tue, 18 Aug 2009 14:38:39 +0000

Everybody is aware with the fact that darker materials absorb more heat from sun than white/light colors, but an interesting data I want to share that black surface in the sun can be 40°C (70°F) hotter than the reflective white surface. This phenomenon occurs in the case of roofs also and heated roof then transfer their heat to surrounded air and contribute to heat island effect, while reflective metallic/ ceramic roof can reflect 65-75 %solar light. According to California energy commissioner “White roofs can cut a building’s energy use by 20% and save consumers money,” and “The potential energy savings in the U.S. is in excess of $1 billion annually.”

http://buildinggreenlife.wordpress.com/2009/08/17/magic-of-white-roofs/

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by Jason Underdown

Jason Underdown — Fri, 24 Jul 2009 19:53:26 +0000

I don’t see how you can infer from this post, or for that matter any post on this blog that I am hateful towards the political right wing.

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by Concerened Citizen

Concerened Citizen — Thu, 23 Jul 2009 02:52:15 +0000

I stumbled upon your post through visiting one of your family member’s blog. I am sorry to say that said family member is far more intelligent and interesting. This family member is also far less hateful towards the right wing. What happened to you?

Comment on Stephen Chu’s White Roof Proposal and Rush Limbaugh’s Response by Richard Warg

Richard Warg — Thu, 02 Jul 2009 22:14:24 +0000

Dear Jason-

Ditto! I started re-painting my house white last week when it hit 111F.

Upon reflection it seems clear that we must eliminate excessive black body radiation in residential areas.

Comment on Creating Printable PDF Flash Cards Using LaTeX by Kortec

Kortec — Thu, 18 Jun 2009 20:32:06 +0000

This fixed the warnings and errors I had quite nicely, except for some of the obligatory overfull hbox chatter. Well done!