>Of course there may be some advantages, but for disadvantages would'nt cement
>(concrete) hives be very poor insulators?

        The thermal insulation value (U, or its reciprocal R) of concrete
is not an immoveable feast.  In particular, if you can tolerate the even
weaker physical properties, incorporation of pumice in concrete increases
its thermal insulation value very considerably.
        And don't forget those coefficients U are for a given thickness,
whereas a concrete hive (once you abandon portability) can be several times
thicker than normal wood.
        So, even in climates where high thermal insulation is desirable for
beehives, concrete might be OK.

R

-
Robt Mann
consultant ecologist
P O Box 28878   Remuera, Auckland 1005, New Zealand
                (9) 524 2949