alt.sci.physics

Dear lister:


On Aug 14, 6:07 am, lister wrote:
> Hi all,
>
> Physics numptie here who is trying to insulate his
> shed from heat in the summer.
>
> Currently I have 1" expanded polystyrene around
> all the walls and ceiling, but I was just wondering
> whether it was worth putting tin foil between the
> polystyrene and shiplap in order to reflect radiated
> heat?

It is most probably aluminum foil, as it is difficult to find tin foil
in the grocery store. A lot of insulation products have this built
in.

> Will this make any difference whatsoever?

Some small difference. Might be hard to measure, except as a dollar
or two in cooling bills over a month (or more). Not sure it is worth
your time and effort to add this in.

> Will the fact that it's touching the shed wall
> anyway mean that heat is simply transferred via
> conduction instead?

The most effect would be had if it were the the surface the sunlight
hit, and it were surrounded on both sides by vacuum. The next best is
neither of its surfaces were in contact with a solid surface
(insulation doesn't count, even your polystyrene). They make a mylar
coated "bubble wrap" that should do as good a job as what you want,
and can be pushed right against the exterior siding.

A mirror gets hotter than anything else, as long as it cannot conduct
heat to some other radiator.

David A. Smith