Self-radiation

I left something out of my essay on Thermal Comfort (under Energy).  I said a lot about radiant heating,  and how the walls themselves act as radiators if they warm up and stay warm.   But of course this also applies to people.

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This is a photograph of an emergency blanket used to keep accident victims warm. As you can see, it consists of a thin, metallised plastic film which reflects light of all wavelengths,  including radiant heat emitted by the body.  Reflecting this heat (actually infrared radiation) back to the body is an important part of keeping warm, and these blankets are a routine component of first aid kits. Of course, a fluffy woolen blanket will also help, and one is recommended; but this conserves only conducted heat: the foil is needed to handle radiated heat.

So, what does this tell us about thermal comfort in the domestic environment? Well,  we need to keep the walls warm so they send back as much radiated heat as we send to them; but it also suggests warm clothing should have a metallised aspect. I think some grayish quilted ski-jackets do this,  but I don’t see this in current winter styling.

 

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