Radiant ceilings deliver comfort

Nov. 7, 2014
Find out the advantages and disadvantages of radiant ceilings.  Radiant ceilings have the MW Rating of Best!

In my October article, we began reviewing all of the different typical methods for delivering radiant comfort. This month’s article will focus on my personal favorite, radiant ceilings.

Radiant Ceilings: On a Montgomery Ward scale of “good,” “better” and “best,” radiant ceilings fall into the best category. They have the ability to deliver more heating and cooling energy than a radiant floor due to the fact that there is no human contact with the emitting surface.

They also have the distinct ability to provide heating and cooling from the same common emitter, thereby requiring minimal air movement to maintain healthy indoor air-quality requirements. For retrofit consideration, they impose the least amount of displacement of space, requiring minimal electrical box extensions for ceiling mounted lights, etc.

Advantages: They make the space extremely comfortable because we are in direct view of the emitting surface, and the emitting surface has no resistive coverings (pad and carpet or throw rugs) to impede the flow of heating and cooling energy into the conditioned space.

One key advantage to radiant ceilings is that they eliminate the possibility of the homeowner covering the emitter with items that do not show on the building blue prints, that being large thick throw rugs and carpeting with thick padding.

If the consumer wants to cover the floor with bear rugs, let him. It will not affect the output of the radiant ceiling. If “future proofing” of the conditioned space is not a major consideration, technically speaking a person can install less emitting surface space for a ceiling than is required by floors. Again, this is due to the fact that there is no human contact between the emitting surface and the people occupying the space.

It is possible to do a 4-foot exterior band of radiant ceiling and be able to keep the space very comfortable. There will be more on “future proofing” at the end of this month’s article.

Disadvantages: Unfortunately, radiant ceilings have gotten off to a slow start and have received a low level of consumer acceptance due to a lot of misguided information. Probably the one piece of misinformation that has held them back more than any other information is the old saw that “heat rises.” In reality, hot fluids (e.g. hot water, hot air) rise. Radiant energy flows in all directions, including downward, from a warm surface to a less warm surface, as part of Mother Nature’s continual efforts to put the space into thermal equilibrium.

People think their heads will be hot and their feet will be cold. From personal experience, I can tell you that my head is only warm when my occasional-use home is in recovery mode (accelerating from 40°F to 68°F) and quite honestly, I find that warmth quite comforting. The other piece of misinformation is the “shadow” effect caused by sitting at a table.

Again, based on personal experience, this is the case while the home is in the deep set back recovery mode, but once all of the mass is charge and the home is stable, you cannot feel any difference sitting at a table or a desk where your legs cannot see the radiant ceiling, and unless it is extremely cold outside, you can’t tell where the heating energy is coming from.

MW Rating — Best: Having personally experienced just about every method of radiant delivery there is, I prefer radiant ceilings where appropriate (radiant floors are still the king of bathrooms, swimming pools and walk-in closets). And when you think about it, with the ability to address heating and sensible cooling, the net installed cost of a comfort system will be less than a conventional radiant floor heating system with a separate forced-air cooling system. It also makes the most sense for sleeping areas.

Why do we install radiant floors and then cover them with thick padding and carpet, and mattresses and box springs, and then wonder why the sleeping area is always so cool?

I mentioned “future proofing” earlier in this article. Although it is possible to decrease the emitting surface area by choosing a higher fluid and surface operating temperature, as we move this industry forward, terms like eXergy become quite obvious. In order to make our systems more compatible with these low eXergy designs, the operating temperature must be as low as possible.

This may require covering a larger surface area with your emitter, but it will make the system design much more efficient and can easily put it into a category that is perfectly compatible with alternative energy, like air source heat pumps, ground source heat pumps, solar PV and others with a typical low operating temperature.

As I have stated before, if we are to get radiant heating and cooling into the mainstream of delivering good radiant comfort experiences, we must take the focus off of “warm floors” and redirect the focus to “radiant comfort” regardless of the emitting surface. Remember, many of our RPA manufacturers now have the functional ability to deliver radiant cooling.

Tune in next month as I help you continue to evaluate your options in delivering good radiant comfort from alternative surfaces. Next up: How do we control these wonderful systems?

All Mark Eatherton material on this website is protected by Copyright 2014. Any reuse of this material (print or electronic) must first have the expressed written permission of Mark Eatherton and CONTRACTOR Magazine. Please contact via email at: [email protected].

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Mark Eatherton

Mark Eatherton material on this website is protected by Copyright 2017. Any reuse of this material (print or electronic) must first have the expressed written permission of Mark Eatherton and CONTRACTOR Magazine. 

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