I've just built a growing case which is illuminated by a 1000w Metal Halide
lamp
and wanted to grow some of the rarer small orchids which would
be suitable.

Can lower the night temps down to 10C with the use of a small air
conditioner
which is mounted outside of the case, the days never get above
25C. It has its own humidifier so that can be set to whatever is
needed.

Can anyone suggest any please?

Thanks for any help given.
Cheers,
Steve