The energy in the form of heat, though, is prevented from leaving because heat transfer through the glass walls is rather slow compared to light transfer.
(The energy in the form of heat; is prevented; from leaving; because heat transfer through the glass walls is rather slow compared to light transfer) (heat transfer through the glass walls; is; rather slow)
The energy in the form of heat heat transfer through the glass walls
is prevented is
from leaving because heat transfer through the glass walls is rather slow compared to light transfer
rather slow