The Fundamentals
What Is Infrared Heat?
The same warmth as the sun. Delivered directly to you.
Infrared heat is not an invention. It is a force of nature. The invisible warmth you feel from the sun on a clear winter’s day, the radiant heat from an open fire or a campfire — that is infrared. An Opranic infrared heater does precisely the same thing, on your terrace, in your conservatory, or beneath your canopy. The warmth travels directly from the source to you, with no need to heat the air in between.
That single property is what makes infrared heating the only form of outdoor heating that genuinely works.
A Force of Nature
Infrared heat warms you, not the air
Infrared radiation is not an invention. It is a force of nature. The sun produces infrared radiation, and these invisible rays are converted into heat the moment they are absorbed by an object — having travelled, undiminished, through the vacuum of space and the open air. When infrared rays strike a surface, thermal energy is released regardless of the surrounding air temperature. The clearest way to understand this is to feel the sun on a cold winter morning. The moment it appears from behind a cloud, you feel the warmth immediately; every surface around you begins to absorb and re-radiate that energy, and the temperature of those surfaces rises even as the air itself remains cold.
An infrared outdoor heater works by the same principle. It produces electromagnetic waves that warm bodies and objects directly — not the air between the heater and you. This is radiant heat: a direct transfer of thermal energy via invisible electromagnetic waves from the source to whatever stands in their path. Conventional heaters warm by convection, using air as an intermediary. That intermediary introduces energy losses and inefficiency under any conditions; outdoors, where that air is constantly displaced by wind, convection heating becomes practically useless.
Infrared radiation warms you directly. Not the air. You.
Three methods
Infrared vs convection: three ways to transfer heat, one that works outdoors
Heat moves in exactly three ways. Conduction is direct contact — hold a warm coffee cup and your hand warms because the surfaces are touching. Useful physics, but irrelevant to a terrace or patio. Convection heats the air. Warm air rises, cools, and sinks again. It is how most indoor heaters work, and indoors it makes sense: walls and a ceiling contain the air and hold the warmth in place. Outdoors, convection becomes a losing proposition. The heated air lifts straight towards the sky, and the wind replaces it with cold air the moment it leaves. You are, in effect, paying to heat the atmosphere.
Radiation is direct energy transfer from a source to a surface, with no reliance on the air in between. It is precisely how the sun warms the earth — across 150 million kilometres of near-absolute-zero space, without a single air molecule involved. Infrared radiation travels, strikes a surface, and is absorbed as heat. It is the only viable way to heat an outdoor space efficiently, and it is the principle behind every Opranic patio heater.
If you would like to go deeper on choosing the right model for your outdoor space, our buying guide for outdoor infrared heaters covers the decision in full.
The sunshine principle
Why you feel warm on a mountain slope in sub-zero temperatures
Infrared radiation is part of the electromagnetic spectrum — the same family as visible light, radio waves, and X-rays. It sits just below the red end of the visible spectrum, which is precisely where the name comes from: infrared means “below red.” When an Opranic outdoor heater is running, you may notice a faint red glow. What you feel is the radiant heat itself — infrared radiation absorbed by the skin and converted to warmth within the body.
The infrared band is broad, and different parts of it behave very differently. Certain wavelengths are absorbed almost entirely by the skin, producing a gentle, comfortable warmth. Others are reflected away or felt as an unpleasant prickling sensation. Choosing the right wavelength is the most consequential engineering decision in any infrared heater, and it is where more than twenty years of Opranic’s development work has its roots.
The human body is 80% water.
That determines which wavelength works.
The Spectrum
Where infrared sits in the electromagnetic spectrum
Infrared radiation is part of the electromagnetic spectrum — the same family as visible light, radio waves, and X-rays. It sits just below the red end of the visible range, which is precisely where the name comes from: infrared, meaning “below red.” When an Opranic infrared heater is running, what you see is a soft amber glow, not unlike the light of an open fire. What you feel is the radiant warmth itself — infrared energy that the skin absorbs and converts to heat within the body.
The infrared band is wide, and different portions of it behave very differently. Some wavelengths are absorbed almost entirely by the skin, producing a gentle, comfortable warmth. Others are reflected away or register as an unpleasant prickling sensation. Wavelength selection is the single most consequential engineering decision in any outdoor patio heater, and it is where more than twenty years of Opranic engineering has its roots.
For a deeper look at the physics of wavelength, surface temperature, and absorption, read our technical guide on how infrared heating works.
Water content
Why 2.2 micrometres is the right wavelength for infrared heating
The human body is roughly 70% water. That single fact determines which type of infrared radiation actually warms you — and which does not. If the radiation is not absorbed by water in the skin, intensity is irrelevant; it either passes straight through or reflects away without producing any heat.
Water absorbs infrared radiation most efficiently in the 2.2–3.0 micrometre range. Radiation at precisely 2.2 µm is taken up directly in the outermost layer of the skin, where the heat receptors sit, and is converted into perceptible warmth rather than bouncing away. That is why the Opranic IR-X Carbon Black element is engineered with its peak output at precisely this wavelength. Every joule of energy goes exactly where it should.
IR-X Carbon Black peak output
Mid-wave is absorbed. Short-wave reflects away.
The skin’s defence
The skin’s natural reflectance: a built-in defence
Skin is not a passive receiver of heat. It has evolved over millions of years under direct sunlight, which means it is remarkably selective about which radiation it admits and which it deflects. That selectivity is a defence mechanism — one that serves us well in nature, but one that also makes the character of infrared radiation matter enormously for the comfort you actually experience.
Infrared that is too intense, or of the wrong spectral character, is largely reflected away from the skin’s surface — much as the harshest midday sun bounces off a pale shirt. It may feel warm at close range, but the majority of the energy never penetrates to where it can do any useful work. Infrared of the right character, such as that produced by an Opranic infrared heater, is absorbed directly into the outer layers of the skin. The sensation is the same gentle, penetrating warmth as a September afternoon sun — the kind that makes you close your eyes and tilt your face upward.
100% natural
Infrared warmth is 100% natural for the body
Infrared warmth is completely natural to the human body. It is the same form of energy the sun delivers on a spring afternoon, the same warmth that presses through a t-shirt on a July jetty, the same radiant heat that lingers in a sun-baked stone long after sunset. Sitting beneath an Opranic infrared heater is to borrow precisely that sensation — and carry it into September, October, and beyond.
The warmth is gentle, even, and felt directly on the skin. It creates no warm air currents, does not dry the surrounding air, and requires no warm-up time. Switch it on, and the heat is present from the very first second. The air around you stays fresh to breathe — exactly as it would on any ordinary evening outdoors — while the quiet, steady radiance is what keeps you outside for another hour.
Air quality
Infrared heating and air quality: a genuine advantage for allergy sufferers
One detail that rarely receives the attention it deserves is air quality. Infrared heating does not move air. There is no fan, no airflow, no stirred-up dust or pollen. For anyone who suffers from allergies, that distinction matters — indoors and out on the terrace alike.
Indoors, an Opranic infrared heater delivers quiet, even radiant warmth without drying the air. It does not disturb settled dust, it does not circulate pollen drawn in through open windows, and it spares you the dry, stifling atmosphere that a radiator running at full output so reliably produces. The air stays fresh and easy to breathe; the room feels more like a mild spring morning than a sealed, overheated space.
Outdoors, the contrast with a gas patio heater is particularly clear. An Opranic outdoor heater produces no combustion gases, no water vapour, and no odour. There is no open flame, nothing interacting with the air around the table. The fresh outdoor air remains exactly that — fresh — while the radiant heat warms you directly.
Infrared is the only heating technology that is rational outdoors.
Outdoor performance
Why infrared heating works better outdoors
Infrared is the only heating technology built genuinely for outdoor use. The difference is not simply physics — it is also about how an infrared heater behaves when the weather and wind are exactly as unpredictable as a northern European climate tends to be.
When wind sweeps across a terrace, warm air is carried away instantly. That is nature redistributing temperature. An infrared heater is indifferent to it. Radiant heat travels in straight lines from the source to you, regardless of whether the surrounding air is moving or still. You can be sitting in a gusting crosswind and still feel the warmth across your shoulders and on the backs of your hands.
An Opranic outdoor heater is also built to live outdoors year-round. Its IP65 rating means it withstands rain, sleet, and salt-laden coastal air without compromise. There is no warm-up time, no gas cylinder to change, no flame to shield from the wind. Switch it on and you are warm from the first second — through the full season from early spring to late autumn, and frequently well into winter.
Independent research
Independent Research Behind Opranic’s Infrared Technology: LTU and Vattenfall 2019
In 2019, an independent study was conducted at Luleå University of Technology in collaboration with Vattenfall’s research division and Opranic. The study, subsequently published in the peer-reviewed Journal of Cold Regions Engineering, examined how infrared heat can be used to de-ice wind turbine blades in Swedish winter conditions. Tests were carried out in a climate chamber at the Arctic Falls facility in Piteå, at temperatures as low as minus 30 degrees Celsius.
The researchers compared different types of infrared heating and established that wavelength and distance are the two parameters that matter most to performance. Longer wavelengths — that is, the medium-wave technology Opranic uses — proved most effective at transferring heat into the target surface rather than reflecting away from it. That is precisely the engineering logic Opranic has built its outdoor heaters on for over 20 years, now independently confirmed by academic research. Read the full research paper as a PDF.
Infrared radiation at comfort levels has also been safety-assessed by ICNIRP, the international expert body on non-ionising radiation. Their guidelines underpin radiation protection recommendations across Europe and confirm that infrared heat of the kind delivered by a patio heater is entirely safe for daily use.
Sources & Partners
- Luleå University of Technology
- Vattenfall R&D
- Journal of Cold Regions Engineering (ASCE, 2022)
- ICNIRP (safety guidelines)
Energy Efficiency
Infrared heating converts 96% of energy into warmth
An Opranic infrared heater converts up to 96% of the electricity you pay for directly into radiant heat. The remaining fraction is emitted as the soft amber glow you see when the heater switches on — the same warm light that makes the skin feel genuinely at ease, even on a cold evening.
No warm-up time. No energy lost to the wind. No idling. Press the button and the heat is there immediately, directed precisely where it is needed. On a typical outdoor terrace, that translates to an operating cost of a few kronor per hour — often a fraction of what a gas patio heater costs to run.
That is the difference between running a heater at full power and hoping the space warms up, and directing exactly the right amount of radiant heat to exactly the right place.
converted into radiant heat
96% of the energy you pay for is converted into warmth felt in the body.
The system
Opranic infrared heating: a complete system, not just a heater
The IR-X Carbon Black element is the heart of every Opranic infrared heater. But no heart functions alone. It must sit within a precision-engineered parabolic reflector that directs radiant energy exactly where it is needed, housed behind a stainless-steel casing and side reflectors that contain and focus that energy, and governed by electronics that hold the element’s surface temperature at precisely the right point to maintain optimal output wavelength.
For over 20 years, Opranic has developed and refined every one of these components as a single integrated system — not as a collection of separate parts. That engineering philosophy is why Opranic outdoor heaters consistently outperform alternatives, both in independent academic research and in real-world installations from Scandinavia to the Mediterranean. No single component accounts for the difference. The system, taken as a whole, does.
To find the right outdoor patio heater for your space, read our buyer’s guide to outdoor infrared heaters. To learn more about the company and the engineering tradition behind the products, visit why Opranic.