this post was submitted on 22 Mar 2026
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Those particular ones might be a waste of energy, but outdoor heaters like that in general are great for in front of hotels, and in the vestibule for doormen at clubs or valets
I responded further down but the infrared equivalent to these are very useful and explicitly solve for the energy waste issue you describe. Infrared heaters canβt heat open air which means heat-energy is transferred right to solid surfaces. It is extremely efficient in areas with any amount of airflow as the heat isnβt able to be blown away as itβs radiating from the surfaces below the heater, not the heater or the air between.
I bet we can take it even further. Switch it out for a phased array of infrared emitters that track and target people based on body temperature. Then it won't have to be on all the time and there's no way it could possibly go wrong.
Nah we can go way further, what we need is to switch from infrared to microwaves. By emitting microwaves at the right frequency, we can directly transfer energy in a super efficient way. We could tune it to make water molecules vibrate and turn that energy directly into heat. Since humans are basically bags of water, they'd be pretty warm without much energy required at all.
That might work. You could use masers, but I think, in the interest of costs, a cavity magnetron and waveguide would be a better choice for generating the microwaves. You'd have to build a large metal cage around the area with the gaps being smaller than the wavelength to make sure you weren't heating anything unintended or causing electrical interference to nearby devices/circuits.
There'll be the problem of the resultant interference pattern in the--what should we call this?--microwave sauna, creating cold and hot spots. You could set it up so the magnetron and waveguide move around, but that's a failure point centered on the most expensive components. It would probably be wiser to put a rotating platform in the sauna to move the subjects through the bands of positive and negative interference for more even heating.
You'll probably need to have controls for power level and time. Can't have the thing on full blast constantly or people will get a little too warm. Those controls will have to be on the outside, so they don't receive interference from the microwaves. Also, it'll be really important to educate people not to bring metal with sharp edges into the sauna, otherwise the potential difference between the magnetron and the point/edge of the metal can overcome the electrical resistance of air, creating a plasma arc that could short the whole thing and electrify whatever the metal is connected to. It needn't be a long list of banned items, just simple things like cell phones, bank cards with chips, zippers, keys, jewelry, dog tags etc.
One of the coolest things about this solution is based on the fact that corn kernels have the moisture to absorb enough energy from the microwaves to make steam and cook internally until they rupture, forming a tasty snack. You could totally put a button on the control panel for making popcorn.
Being around microwaves like that has been proven to melt chocolate bars in pockets, though.
Ra's al Ghul would like a word with you
"All we found was a pile of ashes."
We haven't heard any complaints, though! Just the distant sizzling sound of contentment.
Im wondering how large a phased array of infrared sources would be
Given that they have to be a distance apart relative to the wavelength they're emitting, I'd guess about 10 times larger than a single emitter with the same output. However, because it's able to create beams with cross-sections similar to the profile of its targets, I'd argue it could just have a lower output and resolution with similar performance to a single emitter for half that. Those are wild guesses. Hopefully an engineer is lurking around here somewhere.
Better yet, people just wear better clothes and retain body heat instead of sticking heaters outside.
With respect, I fail to see how that advances shareholder value. How would you even build a recurring monthly fee into the use of clothes?
And usually they are infrared so you're only heating people, not concrete.
I don't think that's how radiant heat transfer works. Should generally heat anything colder than the heat source
Kinda both right, it heats surfaces the infrared energy emitted by the heater can make contact with. It wonβt heat open air which makes it extremely useful in outside environments or anywhere with a potential for airflow. But yeah it does heat everything it does point at, just not the air in between. Really useful for heating furniture to heat the ambient area in addition to the people present.
I dont know how people absorb infared vs concrete, but i do know that once it emits a photon of infared, that energy is gone from the system, regardless of where it is absorbed. Meaning you spend the exact same power heating nothing as heating the air, concrete, or people. As long as the heater is emitting, it is emitting the same amount always.
This parapraph began as a short tangent but now i have a longer question. I was going to explain that the energy delivered does chnage if you prevent the energy from escaping, but now im not sure exactly how. If you, say, reflect all the ir back at the emitter it heats up. Therefore, it emits more blackbody radiation. Im just gonna take a guess and say that blackbody radiation is not the mechanism by which quartz ir heaters operate though. Im assuming they operate closer to an LED, where they are doing fancy quantum magic to directly create the chosen photon and the chosen amplitude, which would be way more efficient. In that case, as the emitter heats up it would have a lower efficiency because the electrical resistance goes up, wasting power. It would also serve to expand the bandgap in the IRED, either reducing efficiency or pushing it into another frequency of light altogether.
However, all that "wasted energy" or "reduced efficiency" has another name... heat. And its a heater. So like.... net energy generation stays the same? I think my confusion is coming from not clearly defining what it actually is im trying to measure or where im taking that measurement.
Why do you think concrete does not get heated?
They are there to stop ice from forming on the walkway of the entrance. There are more for safety than heating.
Elderly and young children's natural thermostats don't regulate as quickly as others ', either.
I'll agree that they have very specific locations where they have reasonable use cases, but the vast majority of where they're located are a waste. Like you mentioned, specifically somewhere with dry desert conditions, where it can get very cold at night rapidly where people are tourists and not dressed properly.