Whether you work from home all day, play hard after hours, or both, your computer adds a measurable amount of warmth to your home. Here’s why and how to calculate exactly how much it heats up a space.
Computers are surprisingly efficient heaters
Of course, anyone who uses a computer knows that it produces heat. If you put the laptop on your lap, it heats up pretty quickly. Anyone who has used a gaming bender with a desktop computer knows that the room slowly gets warmer as the session progresses.
So the idea of a computer adding heat to the room it’s in while running isn’t necessarily shocking to most people. However, what surprises many is how efficient computers are at converting electricity into heat.
Every bit of electricity used by a computer (as well as all electricity used by peripherals such as monitors, printers, and so on) is eventually released as heat.
In fact, assuming you set the space heater to use the same energy as the computer, there would be no finite difference in room temperature between the operation of the space heater and the computer. Both use electricity to operate and both end up “throwing out” waste heat into the room.
You can run the test yourself, but if you’d rather just read the results of someone else using a computer versus calculating a space heater, you can rest easy knowing it’s been done. Back in 2013, Puget Systems, a custom computer company, conducted a test for fun to see if a computer would actually work just like a space heater under the same conditions.
They loaded up a PC with enough GPU and hardware to match the power output of a basic small 1000W space heater they bought for the experiment and tested it in a room isolated from the building’s HVAC system. The end result? Running a gaming PC under load to force it to be as close to 1000W output gave the equivalent result in terms of increased ambient temperature.
We’re sure this comes as no surprise to physics students reading at home. The electrical energy invested in the system has to go somewhere and goes into the room as heat. Whether the source is an electric motor on a fan, a computer, a space heater, or even a toaster, heat eventually enters the room.
As an aside, we’d argue that computers—in a philosophical sense, not a strictly physical one—are even more efficient than space heaters. A space heater converts 100% of electricity into heat, and a computer converts 100% of electricity into heat, but a space heater is limited to simply heating or not heating.
A computer, on the other hand, actually does all sorts of useful and interesting things for you while making the room a little toastier. You can run Doom on many things, though, but you can’t run it on your space heater.
How to calculate how much heat your computer generates
It’s one thing to know that the electricity your computer uses will eventually end up as heat. It’s another thing to determine exactly how much heat it’s putting into your home.
However, there is a wrong way and a right way to get to the bottom of the problem, so let’s dig in.
Do not use the power rating for estimation
The first thing you should avoid is looking at the power rating as an indication of how much heat your computer is generating.
The power supply unit (PSU) on your desktop computer may be rated at 800W, or the fine print on the bottom of your laptop’s PSU may indicate 75W.
But those numbers don’t show the actual workload of the computer. They simply indicate the maximum upper threshold. An 800W PSU doesn’t suck 800W every second it runs—that’s the maximum load it can safely supply.
To further complicate matters, computers do not have a steady state when it comes to power consumption. If you have a space heater with low, medium, and high settings of 300, 500, and 800 watts, respectively, then you know exactly how much energy is being used at each setting.
With a computer, however, there’s a whole power consumption curve beyond something as simple as high/low. This curve includes everything from the small amount of power a computer needs to stay idle, to the modest amount of power it uses for simple daily tasks like browsing the web and reading email, all the way up to the larger amount of power needed to run a high-end GPU- and while playing a demanding game.
You can’t simply look at the power label and calculate anything from that, other than calculating the absolute maximum amount of power a device can use.
Use a real power meter
Instead of judging based on a label, you should actually measure. For accurate measurement, you need a tool that reports the wattage of your computer and peripherals. If you have a UPS unit with an external display that shows the current load (or has software that allows you to check load statistics via a USB connection), you can use that.
We’d consider a UPS a key piece of hardware for everything from your desktop computer to your router – so if you don’t have one now is the time to get one.
If you don’t have a UPS (or your model doesn’t report power consumption), you can also use a stand-alone power meter like the Kill A Watt meter. We love the Kill A Watt meter and you’ll see us use it a lot, like when we show you how to measure your power consumption or answer questions like how much it costs to charge a battery.
Just plug the Kill A Watt into the wall, plug your computer’s lead into the device (so you can measure both your computer and peripherals), then check the reading. Easy peasy.
If you use actual measurement, you will quickly see that the power rating is not the actual power consumption, by a wide margin.
Here’s a real-world example: I monitored my desktop computer’s power consumption with the meter built into the UPS and the Kill A Watt meter just to double-check that the UPS reading was accurate.
The power supply in this machine is 750W. But when it’s on and idle (or doing very basic tasks like writing this article or reading the news) the power consumption hovers around 270W. Playing relatively light games pushed it into the 300W range.
When loaded either by playing more demanding games or by running a benchmark application such as 3DMark that loads the processor and GPU, the energy consumption rises to around 490W. Despite a few moments flickering just above 500W, at no point did the PC come close to the 750W PSU rating.
This is just an example, of course, and your setup may have more or less power consumers than mine — which is why you need to measure it to get to the bottom of things.
What to do with that information
Unfortunately, we can’t tell you “OK, so your computer is adding 500W worth of energy to your room, so it’s going to raise the temperature of the room by 5 degrees Fahrenheit in 1 hour,” or anything like that.
There are simply too many variables at play. Maybe your home is a super-insulated concrete structure with triple-glazed windows and an R-value of insulation equal to a YETI cooler. Or maybe you live in an old farmhouse with non-existent insulation, constant drafts and single-pane windows.
Season also plays a role. When the sun beats down on your home in the summer, the extra bit of heat radiating from your gaming PC can make an otherwise tolerable room unbearably warm. But in winter, it could feel quite cozy instead.
So while that 500W of power (or whatever the value may be for your setup) will go into the space regardless, because all the electricity will eventually become waste heat, what that waste heat means for your comfort level and room temperature is quite variable. If you want to see the actual degrees Fahrenheit change before your eyes, put a table thermometer in the room—this model is great for both at-a-glance information and tracking data with your phone.
All in all, whether you throw a thermometer on the table next to your gaming or not, you’ll have to judge based on your computer setup, your home setup, and what kind of cooling options are available to you, how much power (and subsequent heat) you’re willing to tolerate. .
Furthermore, you may want to consider changing your usage based on your needs and the weather. For example, if you’re actually doing serious on-demand gaming with a GPU, you may need to fire up your desktop to get the experience you want.
Answering emails or just doing light office work? Maybe turn on the laptop instead and reduce the thermal energy pumped into the room from 300W to 50W or less. Many “light” games also work well on a laptop, so you don’t always need to turn on desktop equipment to play.
Just browsing reddit or reading the news? Maybe skip the desktop or laptop entirely and do those activities on your phone or tablet. At that point, you’ve reduced your energy consumption from hundreds of watts to a few watts—and kept your living space significantly cooler in the process.
But hey, if you don’t want to give up all those hours of gaming (nor do you want to add heat to your home and sweat in the process), you can always use a window air conditioner in your gaming room of choice. and stay comfortable and extract the extra heat introduced by your gaming device.