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Kris de Decker and Heating People, Not Places

Kris de DeckerKris de Decker is a freelance journalist, founder of Low Tech Magazine and No Tech Magazine, who has donned a number of hats in his extraordinary career. If a “journalist” sparks an image of a person reporting local and national news on TV, your perception of Kris cannot be further from reality. He is someone who has flipped conventional wisdom upside down through his work (more on that later). Putting his innovative genius to great use, he has carved a new profession altogether, though he is modest enough to call himself a freelance journalist.

There are thinkers and there are doers. There are doers and there are followers. There are people who turn their backs to challenges and there are those who see opportunities within them. Kris has been an open thinker, a persistent doer and someone who looks for opportunities within problems. Be it solving a new problem or refining an existing one – he has the vision to see what most miss out on. A science and technology enthusiast to the core, he has a rare combination of imagination and unrelenting passion that bring about disruptive innovations.

Driving force

Kris has spent over eight years as a freelance science and technology journalist, with keen focus on energy efficiency. In this time, he has travelled across France, Belgium, The Netherlands and The United Kingdom – delivering talks, conducting workshops, and executing consultancy projects for government organizations and universities. His unique ability to draw inspiration from the past enables him to apply traditional concepts to solve modern problems.

As innovation continues to push technological boundaries in the 21st century, there has been a growing belief that the more technology we use to solve a problem, the better the solution will be. A downside to this school of thought is that we often come up with over-engineered solutions, missing out on opportunities to offer simple solutions that require minimal technology involvement. While providing hi-tech solutions at mass levels might be commercially viable (owing to economies of scale), it is not the case when a problem has to be solved at a local level. To solve such problems, Kris has assimilated his learnings from the past and comes up with ways to apply them in the present age. Kris refused to accept the seemingly obvious fact that any modern day problem needed a high end technology solution. Keeping this as a base, he has authored several articles on websites, journals and magazines across Europe. In this article, we focus on one such aspect of his work – the problem with modern day heating solutions and how they can be improved by adopting heating principles from yesteryears.

The problem – keeping people and places warm during winters

Anker Die Bauern und die Zeitung 1867

llustration: People gathering around a tile stove. Die Bauern und die Zeitung, a painting by Albert Anker, 1867.

A large part of northern hemisphere experiences extreme winters. There are places which experience continuous sub – zero temperatures for months. In these extreme conditions, keeping warm is no longer a luxury – it’s a necessity for survival. A heating system that can normalize the room temperature is the need of the hour. Traditional solutions such as lighting up the fireplace seem incapable of providing lasting comfort.

Modern day heating solutions seem to be the obvious choice for this situation. Blowers, heaters and air conditioners provide comfort by heating the surroundings. Heating the air within a room raises the temperature of our surroundings and our body receives heat from them, gaining temperature and eventually, feeling warmer.

Heating people instead of places – an energy efficiency game changer

Kris questions the seemingly fundamental assumption that places needed to be heated in order to make people within them feel warmer. While all the modern research focuses on reducing energy consumption of heating devices and making heating appliances with the maximum “star ratings” at minimum cost, Kris has brought back to life a simple but long forgotten concept of heating people instead of places to solve heating problems. This can be achieved by heating certain parts of a room instead of the entire room or a building. His idea might seem out of line initially but we only need to look a few hundred years back in our history to draw inspiration.

In earlier times, the concept of heating was more localized. Heat sources were utilized to heat only parts of a room, which meant lesser energy utilization. To enhance utilization, insulating furniture such as folding partitions and hooded chairs were used. To heat specific body parts, personal heating sources were used.

Air heating vs Radiant heating

Air heating (left) versus radiant heating (right) in a church building. Source: Fabric-friendly heating, Dario Camuffo.

How does heat transfer take place?

There are three basic modes of heat transfer, i.e. conduction, convection and radiation. Conduction is the heat transfer when two objects are in contact. Heat is transferred from a hotter object to a colder one. Thermal resistance of the object has a big part to play in the rate at which heat transfer takes place. Lower thermal resistance means faster heat transfer and vice versa. This is the reason why metal feels colder than wood, even though both of them are at the same temperature.

In convection, heat transfer takes place through a medium. The air surrounding a hot object gets heated up and rises. Here, air is the medium which carries heat from one point/body to another. This is convection.

Radiation is a very different heat transfer method compared to conduction and convection. The infrared part of the electromagnetic spectrum transfers heat from one point to other, without needing any medium or physical contact. Radiant heat has this unique ability of making people comfortable, even though the surrounding temperature is unpleasant.

Radiant heating devices work on the same principal. They do not heat the air in a room but the surfaces present in an environment such as human skin, furniture, etc. This provides comfort even though air temperature is chilling. “Radiant temperature” and “air temperature” both affect the way we feel. To be precise, a weighted mean of both these temperatures results in “operative temperature” – the temperature we feel at a place.

Localized heating: The old way of warming

In old times, before the concept of air conditioners kicked in, only one room in the average small house had a fireplace. Within that room, temperature differentials could be created, depending upon how far you were sitting from fire. In this setup, objects get heated by a radiant heating source.

Contrast this with an air conditioned room. Its aim is to heat up all the air present in a room. After a while, you would feel the same warmth at all places within a room because of the uniform heating. Though this might appear comforting at first, imagine the amount of energy that got wasted, given that at any particular moment, you would be occupying only a small place in the room. Only this place is actually required to be heated.

How to achieve energy efficiency by local insulation

The concept of spot heating or zone heating works in both the vertical and horizontal plane. In a vertical plane, radiant temperature would decrease as the distance (and obstructions) from a radiant energy source such as a fireplace increases. In a vertical plane, the concept of zone heating only heats the surface placed at the bottom. It can be a floor, table or a bed. This surface does not lose as much heat in upward direction unless it is pointing upwards. What this means is the surface remains warm for a long time and provides comfort.

Contrary to this, when an air conditioner heats up air in a particular room, hot air rises up and goes towards the ceiling. Cold air takes its place at the floor level. This process continues until the entire vertical section gets warm. As we stay closer to the floor of a room than the ceiling, it is not the most energy efficient solution, as most of the energy used up in heating the air was actually not required.

Radiant heating devices achieve energy efficiency by heating only that region in space (and not the entire volume of air) that is required to be heated. If you are sitting close to a fireplace, your body is heated and not the surrounding air. Though there is some heat spent in heating the air by conduction, the majority energy of a radiant heating system is spent in warming the bodies, which is manifold more efficient than heating the entire volume of air in a room.

How to solve thermal discomfort arising despite thermal balance

This process of localized heating poses another dilemma. When you are sitting close to a fireplace, one half of your body would be towards it and the other half (say left) would be facing away. The right half, being closer to a radiant heat source, would feel warmer, as it receives radiant energy from a closer range. The left half, facing away from the source, is left in the cold, losing heat to the cold air. This creates a thermal balance. If there is too much difference in temperature of either side, a person would not feel comfortable despite being in thermal balance.

How to solve thermal discomfort caused by a radiant heating source?

One way to tackle this problem is to keep switching sides after fixed intervals. This would ensure that both sides of your body get equal heat over a period of time. This method, though effective, is at times logically not viable. Imagine asking all your guests to flip around every half an hour so that they can feel comfortable with the heating system!

Our ancestors discovered a solution to this problem – local insulation. It was achieved through a number of tailored furniture designs. Hooded chairs is one such example. To prevent the problem of radiant asymmetry, a chair was covered with wool or leather blankets from behind. This protected the back from low temperatures. The shape of these hoods was often an open one, something close to that of a loudspeaker. This allowed it to create maximum obstruction in the path of radiant energy emitted from the heating source, utilizing it to the fullest in heating up the chair gradually and make the occupant comfortable by preventing loss of heat. Some of these chairs were such designed that they could host more than one person.

Hooded chairs from the nineteenth century. Sources: Period Oak Antiques (left) and Polyvore (right).

Hooded chairs from the nineteenth century. Sources: Period Oak Antiques (left) and Polyvore (right).

Folding screens provide another option to tackle the problem of drafts and cold temperatures. Like the hood in chairs, these also trap radiant heat by creating obstruction and keeping a warm local microclimate.

How modern heating innovations can work with ancient ones

While we have seen all the good parts about ancient heating systems, we cannot entirely ignore modern innovations. Although conduction and radiation as primary heat transfer modes are appealing, it does not imply we should all go back to using fireplaces. Conceptually, the old school thought is energy efficient. However, the choice of heating devices definitely needs a re-look. Imagine the amount of heat that escapes through the chimney of a fireplace. They consume all the cold air from surroundings, often making the room appear colder than it actually is due to cold air flow. The less spoken about resulting air pollution, the better. As we’ve covered previously, tile stoves and masonry heaters are exemplary modern heating devices that can achieve almost 100% efficiency. If wood is your choice of heating fuel, nothing else provides a more environment friendly solution than this. Rocket mass heaters and thermally active building surfaces are modern innovations that implement the concept of radiation based, localized heating in clean, efficient manner.

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