[Biophysics] reduce amount of exhaled water-vapor?

[no_child_left_unleashed at yahoo.com.sg]

The only cite I can find, says that an "average" person exhales
approximately two liters of water into the air in 24 hours.  The
question arises when sizing dehumidification capacity for
air-conditioning systems.  Of course, you remember  that it costs you
about 0.3521 KW-hours to condense that amount of water out of the air
with an air-conditioner.  Which is quite a lot if you have to live on
what you can generate from wind/solar/microhydro.  Heck, it's a lot if
you don't, and oil is running $60/barrel

Can anything be done by a homedweller to safely reduce the amount of
water-vapor he exhales?