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Heating & Cooling Ceilings

Busting the Myths

There are many myths about radiant ceiling panels and some are quite convincing – but if you believe them, you’re at risk of missing out on radiant heating’s advantages. The truth is that radiant ceiling panels can be a great-looking way of making a building more comfortable and more energy efficient. Time then, for those myths to be busted.

Myth no.1

"Radiant heating is a fairly new technology..."

Not true. You might be surprised to hear that radiant heating is a mature and proven technology that has been around for more than a hundred years! The impression that radiant heating is a fairly recent invention is probably a result of its increasing popularity and visibility.

Myth no.2

"Radiators provide radiant heating..."

You’d think so, wouldn’t you? But the odd truth is that radiators aren’t really radiators at all. In fact, radiators generate only about 20% of their heat through radiation and 80% through convection.

To briefly remind ourselves of the difference, convection is the transfer of heat from one place to another by the movement of fluids or gases – and so, in heating spaces, convection heats the air, which in turn heats the objects and people in contact with it. Radiation is the transfer of heat by electromagnetic radiation, generated by the thermal motion of charged particles in matter – and so radiation heats the solid objects in a space.

Myth no.3

"Radiant ceiling panels are just radiators in disguise..."

Not true. Unlike radiators, which mostly heat the air in a space, radiant heating panels really do radiate, heating the solid objects in a space such as people and furniture, whilst benefitting from re-radiation.

In radiant ceiling panels, radiator technology is cleverly adapted. Take a radiator, remove the convectors from the back, insulate it and install it in a ceiling, and you’ve converted it to a radiant panel. These changes alter the heat output from 20% radiant and 80% convection heating to 70% radiant and 30% convection heating.

Myth no.4

"Because warm air rises, underfloor heating must be better than heated ceiling panels..."

This is untrue for two reasons.

Firstly, the types of heat output from underfloor heating and radiant panels are different. Underfloor heating is convective because it primarily heats the air in a room. Radiant panels are radiant because they heat solid objects in their ‘line of sight’, in the same way that radiant heat from the sun can heat you without necessarily heating the air around you.

Secondly, there’s the matter of efficiency. Although underfloor heating will provide a consistent temperature across a space, it doesn’t take into consideration the occupancy levels in that space or how the space is used. Also, highly resistant floor coverings, such as certain carpets or wood, can significantly reduce the amount of energy that penetrates them. Radiant panels aren’t muffled in this way.

Myth no.5

"Because warm air rises, floor- and wall-mounted radiators must be better than ceiling-height radiant panels..."

Convective warm air rises, yes - but radiant heat can radiate in the direction in which its source is pointed, including downwards. To give one spectacular example, the sun’s radiant heat reaches us on earth after travelling more than 90 million miles. There’s no pretending that radiant panels are quite that powerful, but they are plenty strong enough to send heat to occupants and objects in a room from heights as great as 30 metres.

Myth no.6

"Space heating, through split units or fan coils, is more comfortable than radiant heating as it heats the space in a room rather than the objects..."

Again, not true. To keep occupants comfortable, it isn’t necessary to heat great volumes of air around them, and it can be wasteful of energy to do so. It’s more efficient to heat the human directly by radiant heating. Indeed, radiant heat feels more natural as it’s more like the sun’s rays.  

The effectiveness of space heating through split units or fan coils (air conditioning) is influenced by the size of the room and the number of units installed. Depending on which areas of the room are heated and the air that’s being heated (determined by factors including the fabric of the building), space heating can prove inefficient and costly. Conventional (air) heating systems allow distributed heat to collect in areas where it is more likely to escape, for example along ceilings and walls, so that achieving a comfortable temperature can be difficult. One of the key advantages of radiant ceiling panels is that heat can be directed to the interior of the space, reducing or eliminating excessive temperatures on outer walls and ceilings.   

Myth no.7

"Heating that radiates from the ceiling must make your head hot..."

Even if you were ten-feet tall, this shouldn’t be true when radiant heating panels are correctly installed. It is true that as the mounting height of the panels is increased, the intensity of the heat is reduced and the output is spread over a greater area, but for installations up to 10m there is no need to increase the panel output. There are easy-to-calculate formulas for systems higher than this. Panels should be spread at a ratio of 2:1 to their mounting height, so that a panel mounted at 3m will provide a radiant field of 6m.

Myth no.8

"Delivering heating and cooling within a building – doesn’t that mean a cluttered, complex and costly solution?.."

The versatility of radiant panels enables them to provide heating or cooling, or both simultaneously, eliminating the need for air conditioning units. And simultaneous heating and cooling from radiant panels costs less to maintain or service than air conditioning units that are used for both.

As well as being versatile, radiant heating and cooling panels are adaptable for use with alternative energy sources, such as solar panels and heat pumps.

Myth no.9

"Radiant heating panels look odd hanging from the ceiling..."

The main consideration is whether to have radiant panels incorporated within the fabric of a building or to have them free-hanging. Each has its own advantages, so choice may be influenced by the fabric of the building and whether installation is part of a new build or a refurbishment project.  

Zehnder offers a great variety of design styles, with ceiling sails and panels in a multitude of different sizes, shapes, and colours. Some options can also incorporate additional services, such as lighting.

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