Computers as a Heat Source
IT'S not a secret - or hardly a secret - that we have many computers and screens running here in "the offices". Last year it was 9 computers, now it's down to 7 (laptops) and they're constantly wired/connected to half a dozen external monitors. They work non-stop, albeit some go to sleep if unused for a period of time. Each of these produces heat, some more than others (depending on activity too, as modern PCs throttle down or re-scale CPU clock speeds). Let's consider the amount of heat they can emit*.
Depending on the type of computer, screen size etc. the emissions of heat will vary. Using TVs (or "smart" TVs) as a reference, some dudes online say that nearly all energy entered into the screen (TV) will be released as heat. "Obviously," a dude said, "some of the energy is given off as light and sound but the majority is emitted immediately as heat. I’d guess at around 90% so if your TV rating plate states 30 Watts maximum, the heat generated will be less than 27 Watts."
Based on intuition and common sense, this isn't far from the truth and the same goes for laptops, where a lot of energy is consumed (when idle) by the monitor that's built in.
Now, suppose you have over a dozen activated monitors in a room or two. Suppose some are taking up just 20 Watts each, on average. That makes a total of around 200 Watts, more than what the aquarium makes if it works non-stop to warm up the water. A decent heating device can operate at 1,000 Watts or more (as high as 2,000 or above), but for a couple of rooms (or a floor) not that much is needed. That means that insulation alone (in a room with many computers) can be OK in a night with outdoor temperatures close to -10**. Accounting for factors other than energy emissions, it can be a "breeze", relatively speaking, so a lot of energy gets recycled or reused.
More than 20 years ago when I worked at MCC (not accidentally the name of the first GNU/Linux distro***, ever!) our offices were attached through the shaft to the datacentre feeding off JANET. The offices - including mine (I had my own office at age 21) - were heated by using energy from servers in that datacentre. We should still be able to do this. In cold days there's no point spewing out the energy outwards rather than inwards. █
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* Set aside factors such as body heat (clothing too), double glazing (insulation), the 200 Watts heater inside the aquarium, hot beverages, radiator (or central heating) etc.
** This is relevant today because from almost 20 degrees last January (in the north) we've fallen to -8 as expected tonight for Manchester ("temperatures set to plummet as low as minus 16C in some areas," says local news). It's hard to recall a night (or day) this cold here, but it's not unprecedented.
*** Owen, who was my colleague at MCC for several years, had created MCC. After all those years he's still in the University of Manchester (or Victoria University of Manchester, prior to the UMIST merger).