Looking up to radiant ceilings for heating and cooling

radiant panel
CC BY 2.0 Lloyd Alter

Most North American homes are heated, cooled and ventilated with forced air. Some have radiant floors and almost none have radiant ceilings. In fact, many think that radiant ceilings can’t possibly work. After all, heat rises! We want warm feet, not a hot head! And cooling? It will be raining condensation!

Well, no. In fact, hydronic radiant ceilings, like these made by Italian manufacturer Messana, make a lot of sense, perhaps more sense than radiant floors and certainly more than forced air.

Most North American homes with forced air heating and cooling have hot and cold spots, noisy ductwork but are a very effective dust moving system. Most also get their fresh air through the leaky walls rather than any kind of controlled ventilation system. As houses get built to higher air tightness standards, proper management of ventilation becomes more important. As they get built with more insulation they need less heating and cooling. So it becomes logical to separate the ventilation from the heating and cooling, because really they are two different things with different requirements.

That’s when radiant heating and cooling becomes really interesting. But radiant floors have their own issues; as Alex Wilson noted in his book Your Green Home,, “it's a great heating option for a poorly designed house.... For the radiant floor system to provide enough heat to feel warm underfoot (the feature everybody likes with this system) its going to be cranking out more heat than the well insulated house can use, and it will likely cause overheating.“

single panel© Messana Radiant Cooling

Radiant ceilings don’t have these problems because people are not usually in contact with the ceiling, so it can be radiating heat for warmth or absorbing it for cooling without problems of conduction. They also work just as well or better, because the operative word is radiant; as Robert Bean notes in Healthy Heating,

Radiant heating systems provide comfort by warming the interior surfaces which reduces the temperature difference between your clothing and skin and the interior surfaces which in turn reduces the loss of body heat via radiation. You see it's not necessarily the radiant energy you are absorbing - it is the heat you are not losing which results in perceptions of comfort….Radiant cooling works in the opposite direction of heating by encouraging the loss of body heat via radiation...it is the loss of heat from your clothing and skin via radiation which provides the cool sensation.

And as long as the panel is kept above the dew point, there is no issue of condensation and raining in your room.

radiant panels© Messana Radiant Cooling

The Ray Magic from Messana is a lot easier to install than an underfloor system; it is a prefabricated system built behind a sheet of drywall. The pattern of the piping is printed on the facing paper so that installers don’t accidentally puncture the plastic tubing, which is installed in aluminum spreaders to heat the gypsum evenly. Special connectors snap the tubing in the panels together.

It is 1-1/2” thick with its EPS backing, so it actually has a great sound transmission coefficient on its own, much better than a sheet of drywall. And because it is on the ceiling, it can run hotter or cooler than a floor, typically up to 100°F for heating and 56°F for cooling, temperatures that would be really uncomfortable if you were standing on it.

panel pieices© Messana Radiant Cooling

There is also less thermal lag because gypsum board is a good conductor and not very thick; consultant Tom Tesmar notes:

Radiant ceilings accelerate fast, when needed, to meet a big change in heating load. They dissipate energy fast as well. The responsiveness of radiant ceilings makes them excellent for modern controls, placing energy where it is needed when it is needed, and achieving superior comfort and efficiency. Some high mass radiant floors are sluggish in that they take a long time to accelerate to meet the load.

He also says that radiant ceilings can cost half of what radiant floors cost, and notes that they are great for retrofits- “It is very inexpensive and easy to lower a ceiling to accommodate the radiant ceiling, but difficult to raise a floor.”

Mesanna also notes that their panel system “is an effective way of reducing labour costs compared to both forced air and radiant floor systems. Its installation is simple and straight: the job is done in no time at all.” That can certainly not be said for radiant floors.

Messana was exhibiting at the North American Passive House conference in New York, which makes some sense; Passive houses do not need a great deal of heat or cooling and a radiant floor would rarely turn on. But a few radiant panels in the ceiling might be enough to do the job nicely. However I suspect that it might do better in the pretty good house market, where a little more heating and cooling is needed. If one can get over the preoccupation with toasty toes, radiant ceilings seem to be a really interesting option.

Tags: Air Conditioning | Heating | Italy | passive house

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