Discussion on:

Color-changing roof tiles can absorb, reflect heat with the seasons

White roofs and cool roof technology performed remarkably when we
completed several thousand hours of advanced infrared to see how the
roofs were reflecting or absorbing the sun's rays. These tiles have
the potential to save on emissions but there is a very real concern.

There isn't a time when you want tiles to be absorbent on the outside
of the building because you will create urban heat islands and change
weather. The walls of the buildings should be white, shaded or
protected from solar radiation as well.

Buildings are designed and insulated for very specific temperatures
and absorbent finishes on the exterior can compromise that. Here is a
link to a youtube video we completed to show how absorbent finishes
contribute to urban heat islands and climate change. Watch the trees
from neighbors protecting buildings across roads.
http://www.youtube.com/watch?v=1EmBQcXr6ng

This is thinking outside of the box that has real possibilities.

I also like the idea of polymer based photovoltaic cells printed on the same presses that Australian currency currently uses for producing a roof filled with photovoltaics. I believe that the efficiency is now fairly poor, but improving,but the cost is low. The idea being presumably to produce electricity producing roof tops that can be marketed much the same way and for much the same cost that colourbond roof sheeting is currently produced for.

If it absorbs heat when it's cold outside, how does it know it's still cold outside? Dark (infrared-absorbing) surfaces can take in a lot of heat, even when the ambient temperature is significantly lower - like asphalt melting snow on a sunny mid-January day. Sounds a bit self-defeating to me. If end-user costs are inexpensive enough and the product is durable, it will make the decision easy, but if it will be expensive to buy, it sounds like a tough sell to me.

Did these guys test conventional thermochromics; surely there must be a thermal analog to electrocromics?

Clever idea.

Suncat2000 brings up important questions. Solar radiation is 365 days
a year regardless of season. We completed several thousand hours,
several years and seasons to document solar interaction with
buildings as well as development. The information contradicted our
own professional education in the calculator but the accuracy of the
data couldn't be ignored. When the sun comes up it hits the walls
first and impacts the entire building throughout the day.

In July when it was 92 degrees F outside and in the afternoon, we
documents the walls of buildings as high as 198 degree F because of
solar radiation.(not good for a building insulated for a max of 92
degrees F) In February of this year on a 32 degree F day in Canada,
there was snow on the roof but the dark exterior walls were 170
degrees F.

For education only we completed several time-lapsed infrared videos
and there are 3 of them for you to view at the link provided. The 3rd
video shows the impact of solar radiation on the inside of the
building. Right after that there is an image of a radiated cutblock
in the winter. www.thermoguy.com/urbanheat.html

re how does it know, you couple it with a heat exchanger (think forced air or flowing water) which is then used to heat the inside of the building.

the problem is in the present form its just a gimick and it needs proper thought in order to make it a viable piece of technology.

Thanks for working on this. The model I made in the 1970s using digital chemical thermometers was rudimentry, as it varied too many colors at various temperatures. This can be incorporated as granules on shingles or as paint pigments.

The problem I had with paint pigments changing colors was "perceived buyer resistance" to telling freinds directions to their house ... "It's the light blue house on the right, unless it's between 70 and 80 degrees, in which case it's yellow, except in Winter it'll be dark green" ... keep up the work guys

This is a great idea but another company has already thought of it. Check out movingcolor.net.

This is a great idea but another company has already thought of the idea. Check them out at movingcolor.net.

This is a great idea but another company has already thought of it. Check them out at movingcolor.net.