If you have a light, or indeed any electrical device, which uses
100 watts of electrical power, then it is fairly safe to say that
you will ultimately end up with 100 watts of heat going somewhere.
A very efficient light will emit a greater fraction (though still
not very large) of this initially as light. But once the light has
bounced around the enclosure and been absorbed, it is turned into
heat. I imagine that it is a very tiny fraction indeed of the light
which is actually absorbed by the plants and used for photosynthesis.
This bit of the energy is temporarily stored as chemical energy in
the growing plant, and doesn't finally emerge as heat until the
plants rots and the chemicals turn back into the simpler molecules
from which they were made.
So what I guess I was getting at is: If you have a more efficient
light, then you will be able to use one of smaller power and still
grow your plants. If you use one of the same power, you will get the
same amount of heat - but more of it initially as light.
And finally - back to something more interesting: My Cephalotus seeds
from Rowland (Bedford, UK) turned up today - the first packet they
sent me was accidentally empty, so now they have sent me 2 packets,
with 5 seeds in each, as compensation. What do I do with them?
Is chilling, as for Sarracenia, needed?
Clarke