Design temperature

[vinod]

Why AC design temperature keeping 23°C in winter and 27°in summer. Winter set point is less than summer set point . please advice.

[HVACRAU]

For the reason of energy saving.

[mikeref]

Considering where you are, i would say it would be to conserve electricity.
27 C for summer is warm by Australian standards. Generally 22*C is the average Summer/ Winter target.

[Tesla]

Hi Vinod
Two reasons
1 energy savings
2 comfort - minimising thermal shock
http://www.google.com.au/search?q=ashrae+comfort+chart&hl=en&client=firefox-a&hs=iOg&rls=org.mozilla:en-US:official&biw=1595&bih=911&prmd=imvnsb&tbm=isch&tbo=u&source=univ&sa=X&ei=JAgiUMrFFdGXiQfSqIDwCQ&ved=0CFIQsAQ
shows some ASHRAE comfort charts. I think I used the 65 chart at an energy saving company. This takes into account if it's a hot day people dress for it and if they are sitting in an office gossipping or surfing the net they are not using energy therefore need less cooling. It caters for 90% of people where 10% would complain. The old standard in Ausie was 22.5degC + or - 1.5degC.
23degC in winter is a bit warm unless it is a much warmer day outside.

[vinod]

Does it mean humidity also a factor?

[Brian_UK]

I seem to remember that some say that you only need the indoor temperature to be lower than the outdoor not that you need a specific temperature for comfort.