I set the AC to one or two degrees below the ambient temperature. It gives surprisingly good enough cooling and also cuts energy consumption. People in my lab try to create a hill station by setting the temperature at 16 deg C, but I overrule with an iron hand! (senior most member :P).

The reason why setting the A/C temp at just 1 deg C below ambient works is that AC not only reduces temperature, but also humidity, which makes it feel much cooler (see heat index). Setting 16deg C is actually pointless in a poorly insulated concrete constructed building as AC struggles to reduce the temperature to below 24 deg C.