QUOTE : It is amazing, he said, how little variation, too hot or too cold, can lead to complaints. We have efficient HVAC systems - that stands for heating, ventilation, and air-conditioning - and in the summer, we try to keep things ten to fifteen degrees cooler than it is outside. We are constantly checking them, so it is a big operation. But of course no one notices the temperature unless it becomes uncomfortable, when the nozzles get blocked, or there's a local break-down in the system. And, he added with a laugh, you don't ever notice your oxygen until it's gone: something goes wrong with the HVAC, even for fifteen minutes, and people are ready to riot.