On Thu, 03 Jul 2014 21:28:13 -0700, Jeff Liebermann
wrote:

On Thu, 03 Jul 2014 18:40:06 -0700, RobertMacy
wrote:

Ceiling exhaust fan !!! when it's 105 outside no way!!! you want me to
suck in outside air at those temps??!!

Let's see at night 81 during day 105, making the average high side of 93,
sounds about right.

I thought it gets kinda cold at night in Az. I've only been there
once. It was quite hot during the day, but we nearly froze sleeping
in the car at night.

Since I painted my house a darker color and take advanatage of 'night time
radiation' the average in our house has dropped substantially. Who would
have thought? dark house = cooler average, light colored house = hotter
average. but true we noticed a difference the moment the house was painted.

In some areas, white rocks and white roofs are required by code to
reduce air conditioning requirements. It's suppose to reflect the
sunlight instead of absorbing it. Now, you're telling me that the
collective wisdom of the local planning department might be wrong? Are
you sure?

From New York:
http://whiteroofproject.org/about/mission/
A roof covered with solar-reflective white paint reflects
up to 90% of sunlight as opposed to the 20% reflected by
a traditional black roof. On a 90°F day, a black roof can
be up to 180°F while a white roof stays a cool 100°F
reducing cooling costs up to 40 percent.

The problem is that the temperature of the roof only tells part of the
story. If the ceiling area was super insulated, the indoor
temperature would be independent of the roof temperature. Kinda looks
like this is based on the assumption that some of the roof heat is
conducted into the building interior. That works, but I suspect
varies radically with building construction and ceiling insulation.

The advantage of a black roof might be because black radiates heat
better than white. The black roof might be hotter during the day, but
as soon as the sun goes down, a black roof will cool down quicker than
a white roof. That might affect the average.

Mo
http://whiteroofproject.org/research/scientific-data/
http://whiteroofproject.org/research/urban-heat-islands/
http://en.wikipedia.org/wiki/White_roof
http://www.globalcoolcities.org
http://www.nyc.gov/html/coolroofs

Unscientific anecdotal drivel: My office building was blessed with a
shiny new white roof in Oct 2013. It was previously black asphalt and
a thin layer of fine gray rock. It seems much cooler inside this
summer, but I have no measurements to prove it.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558