"gardenlen" wrote in message
...

wow so we might run out of water to drink? that's a different slant.

does anyone ever think that building and designing a home that needs
no air con might be the way to go long term.

that way then the 2 evils of air con'/cooling don't factor in. but
anyway lets waste good drinking water cooling someone down.
evaporatives add to the humidity which at the end of the day make the
whole situation a wholke lot less comfortable so more cooling is then
used.

As I said, neither refrigerated nor evaporative cooling is desirable.
Passive design is of course the ideal way to go, but isn't always feasible
eg existing poorly designed apartments and houses. However where the
decision is made to go for some form of mechanical cooling, I would rather
see evaporative used in appropriate climates like Melbourne's than
refrigerated cooling. As I said previously, I think its the lesser of two
evils. Coal is (1) a depletable resource and (2) one of the major sources
of greenhouse gas. Water on the other hand is not depletable - the problem
with water (1) it gets dirty when used by humans and consequently does
environmental damage and (2) the location and frequency of precipitation
changes, eg causing droughts and floods in specific locations. Drought and
flood in specific locations is (in part) a consequence of climate change,
not the cause. In any event, the real problem with water is not evaporative
air conditioning - approx 90% of all water consumed in Victoria is used for
farming, almost all of it grossly inefficient (the figure is more like 80%
for Australia as a whole IIRC, probably because irrigation is relatively
more important in Vic). In other words, I suspect that refrigerated air
conditioning is a (much) bigger part of the energy problem than evaporative
cooling is in relation to the water problem.