Yes, stop breathing (sorry, couldn't resist).

Humidity in living quarters is best controlled by ventilation. That need
not be excessive, 10 min 3-4 times a day, with all windows open and
heating switched off is quite sufficient. During that short time walls,
furniture and the like do not noticably change temperature, so that the
heating system only has to warm up the air afterwards, this is
relatively cheap because of its low heat capacity.

The use of cooling systems should be limited to really extreme
conditions, i.e. ambient temperatures in excess of about 40 degrees
Celsius. Temperatures below that value can be controlled by appropriate
building construction to keep room temperatures in the upper 20s. This
is not only cheap but much healthier when changing between hot outside
and cold inside. And people have done that for thousands of years before
aircon became available.

Fup set to bionet.biophysics

Well, if the air temperature is at or higher than 37C and the relative
humidity is 100%, you won't lose any water via your respiratory system,
but that doesn't help either, does it?  Your exhaled air will always be
at 100% saturation at body temperature.  The drier and colder the air
you breathe in, the more moisture you lose when you exhale.

If you're in Singapore, as your address suggests, the outdoor air is
always hot and humid, so ventilation may bring more moisture into your
air conditioned home than breathing will.  Of course, that doesn't mean
you should seal yourself in beyond some reasonable level.

Other sources of indoor humidity are moisture from cooking, bathing,
drying clothing and (if you overdo it) aquaria.  Get a tea kettle with
a whistle, and don't fill it too full.

I'd recommend you look for other places to save electricity.  Turn up
the thermostat on your air conditioner, don't run it when you aren't
home, or perhaps just air condition the room you sleep in.  People
survived without air conditioning until just a few decades ago, and
most still do, even in the tropics.  Hot humid weather is easier to
take if you don't keep exposing yourself to cool dry environments.
Fans are a lot cheaper to run than air conditioning, and can be quite
effective.

Some other places to save are conserving hot water if you have electric
water heating (e.g. use cold water for laundry, hand wash small loads
of dishes, fix dripping taps), don't leave appliances and electronic
equipment on when not in use, and replace incandescent light bulbs with
ones of lower wattage, or with fluorescents.

Keep breathing!