Heat Flow Meter

Has anyone ever seen a heat loss meter?
I have an idea how to make one using infrared and ultrasound sensors and getting a transfer function as if it was a black box.
Once you figure out the software, making the device should be very cheap.
                 - = - Vasos Panagiotopoulos, Columbia'81+, Reagan, Mozart, Pindus, BioStrategist          http://www.panix.com/~vjp2/vasos.htm ---{Nothing herein constitutes advice. Everything fully disclaimed.}--- [Homeland Security means private firearms not lazy obstructive guards] [Urb sprawl confounds terror] [Phooey on GUI: Windows for subprime Bimbos]
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Being a dirt- and oxide-sensitive surface effect, emissivity is difficult to characterize: http://en.wikipedia.org/wiki/Emissivity
This shows the 20:1 range of variation for bare aluminum: http://www.engineeringtoolbox.com/radiation-heat-emissivity-aluminum-d_433.html
Right now it's 32F outside in the shade. A brushed, anodized aluminum plate that I washed and left to dry in the back of my truck measures 59F in the early morning sun, with a fine type K thermocouple held in contact with a Q-tip.
The simple way to quantify and integrate the various heat loss paths is to measure a controlled heat -input- and equilibrium temperature or heating/cooling rate, which answers the original question by a different method.
I figure the heat loss from my house by recording the indoor cooling rate with the heat off versus the outdoor temperature. The answer is around 2% of the difference per hour, a piecewise approximation of an exponential process. When the sun is out the indoor temperature is stable at about 15-20F above outdoors.
jsw
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