On a roof you’re nearer the sun so it’s bound to be even hotter than at ground level. Yes, being baked alive on a dangerous roof makes your inadequate office desk fan look like unimaginable luxury. There’s also shitloads more wasps’ nests when it’s hot, which you’ll discover when you’re cutting hedges. The only real danger of working in a hot office is brain damage from people repeatedly saying ‘Hot, isn’t it?’ Your office may be deeply unpleasant and stuffy, but you’re pretty sure it’s not 1,300C.