Basement HVAC

[JohnMazz]

need advice on how to design an efficient HVAC system in a besaement.
some general rules of thumb and design suggections would be helpful.

[suemarkp]

This is a rather vague question. You should post specifics in the HVAC group and not this one -- this is the brag forum and many people may not look here for questions.

Basements generally have low heat gain and loss, so the system typically doesn't have to be very large.
You need to calculate your heat gain/loss, preferably by doing an ACCA Manual J calculation.
Do you have preferences on how you want to do heating -- radiant, forced air?
Do you have a preference for energy source -- electric, gas, oil, propane?
Do you know how to calculate the least expensive energy source?
If you do forced air, you should do an ACCA manual D calculation to size your ducts.
Do you have special air filtering requirements?
Do you have humidity issues?

Efficient doesn't matter much if the system doesn't perform to your requirements. You need to define those first.