I cheat as I generally extract brew/mini mash /hop tea. I do a reduced boil volume 6-8 litres of a 21 litre brew length. A couple of near freezing bottles of water to hand to make a temp adjustment. Last time I checked cold water from tap it was 14c. My process means chilling not required. On the odd occasion I need to pitch yeast in high 20's+ I boil a bit more water.