The author brings to this edition a profuse reflection on the radiant ceiling, an initiative that seeks to contribute to the luenga journey of the industry towards the goal of energy saving. by: Alfredo Sotolongo*
In the constant search for new or old systems and components, anywhere in the world, to achieve energy savings I find very interesting an application in which we are working at the moment. It is the radiant ceiling, either for cooling or heating. This is a European development product of the culture of energy saving that is much more rooted in Europe than in America. Although in this opinion piece we are going to concentrate on the cooling that requires more care in its application,
The panels that make up the radiant ceiling have inside a coil through which cold water passes at temperatures always higher than the dew temperature of the air inside the conditioned area, which avoids the possibility of condensation in the panels. Energy transfer occurs by means of radiation and convection. Achieving the necessary comfort without any exaggerated air movement, even in areas conditioned with high thermal load.
As we all know, radiation is the process of heat transfer by which heat flows from a high-temperature body to a lower-temperature body when those bodies are separated from each other. Radiant heat is understood as the energy emitted by a body by means of electromagnetic waves. The total radiation that is emitted in a known area and time can be measured using the Stefan-Boltzmann equation.
While when the bodies are sufficiently far apart, heat transfer by convection occurs. It is the process of heat transfer by which heat is transferred from a body of higher temperature than the air that surrounds it which heats that air and moves to bodies that are at lower temperatures, which creates the cycle called natural convection.
The area of panels that are selected to install on the ceiling is directly proportional to the thermal load of the area to be conditioned. The construction of the panels and the materials used in it allow the most effective heat transfer by radiation or convection. By means of proportional thermostats located in the conditioned area, through modulating valves it is possible to maintain the balance between the thermal load and the mass of cold water that passes through the tubes of the panels. In addition, to eliminate any possibility of condensation on the panels, it is recommended to install a dew temperature sensor in the conditioned area which will reduce, in the remote case that it is necessary, the flow of water to the panels regardless of the signal of the thermostat.
Among the companies that have researched and managed to develop radiant ceilings are Metal Aire and Barcol-Air, both with high European technology which has been applied around the world with excellent results.
The radiant ceilings have varied benefits, from the architectural point of view since it allows the architect to specify a ceiling that harmonizes with its interior decoration with a variety of colors, eliminating air diffusers among other things. Also, the mechanical designer eliminates the electrical consumption of the motors of the handlers, the cost of them and obtains an extremely silent air conditioning system.
For the owner of the building, in addition to energy savings, it is assumed that due to the reduced space needed within the ceiling is saved in building materials. In addition, for approximately every seven floors one more floor can be added while maintaining the maximum authorized height for the building.
As I always tell you, any product or system for more energy you save has to be able to be justified, not only by how quickly the investment is recovered, but also because it has a practical application.
*Engineer Alfredo Sotolongo, president of Protec, Inc., is certified as a professional engineer in Puerto Rico and the State of Florida; has more than 40 years of experience in the application and sale of systems and equipment for energy conservation. He is a member of ASME (American Society of Mechanical Engineers), AEE (Association of Energy Engineers), with whom he is certified as an Engineer in Energy Management; he is also a member of ASHRAE and was president of the Miami chapter of that association. He has also presented numerous talks on the subject of energy conservation.
