This news article was originally written in Spanish. It has been automatically translated for your convenience. Reasonable efforts have been made to provide an accurate translation, however, no automated translation is perfect nor is it intended to replace a human translator. The original article in Spanish can be viewed at Sistemas radiantes: sostenibilidad y ahorro energético

With them are removed the radiators, which rooms earn in aesthetics and space

Radiant Systems: sustainability and energy saving

Source: Rehau 03/11/2009

November 3, 2009

In recent years the radiant systems have undergone a revival thanks to the use of new technologies, modern methods of calculation and the polymeric materials of new generation. The reasons for this renewed success are found in some of the typical features of these systems: high degree of comfort, energy savings and increase in the available space in the rooms with the removal of the radiators.

The constant technological development has allowed also increase the possibility of installation of these systems. On the basis of the traditional "ground" radiant today provides a broader range of solutions that offer the possibility to install the system also in walls and ceilings. This makes it possible to always find the ideal solution for each client. This development is reflected not only in the possibilities of installation of the system, but also in the possibility of its use throughout the year, either for the heating in winter to refresh in summer.

Radiant systems are now able to ensure maximum comfort and reduce annual energy consumption; In addition, the system eliminates radiators, which spaces the rooms earn in aesthetics.

Comfort

With radiant systems the transmission of heat is mainly by thermal radiation, by means of surface temperatures slightly above the desired ambient temperature.

The homogeneous distribution of heat, typical radiant systems, allows to reach a thermal equilibrium between the human body and the air-conditioned environment, thus increasing the feeling of well-being.

The temperature of the surfaces has in fact an incidence highlighted on the feeling of comfort. As it allows to observe the following chart, there are precise temperature limits which can not be exceeded by medical and physiological reasons:

Feeling of comfort based on temperature environment TRL and the temperature of the surfaces that surround the TF environment.

The advantages of radiant systems in terms of comfort are evident. In system of heating the value limit of radiating surfaces has been established in a maximum of 29 ° C (see links in 1264: underfloor heating.) (Systems and components) with an ambient temperature of 20 ° C. Thanks to existing systems, in practice the surfaces temperature hardly reaches this value, typically remaining among the 23 ° C and 25 ° C, temperature values more favourable to the feeling of comfort.

The same phenomenon can be considered for the holidays period (refresh scheme), since the surfaces temperature reaches values between 21 ° C to 23 ° C with a temperature of 26 ° C.

Refresh scheme also completely prevents cold air currents that could disturb the sense of comfort. In summer, in fact, radiant systems are not intended to reduce the temperature of the air (as it is in the traditional air cooling systems) they remain cool the atmosphere of the building.

Thanks to the integration of dehumidifiers specially designed for the system is also the optimal level of moisture in the air (55-60%).

For complete comfort benefits, the radiant system has also present the thermal profile in regime of heating for the winter.

It is generally known that traditional systems tend to overheat the ambient air in the higher areas of the premises and, accordingly, to suffer losses of temperature in areas more low.

Underfloor heating systems ensure an optimal very close to the ideal thermal profile instead. The following figures highlight the differences of thermal according to the heating system used profile:

Energy saving

Energy conservation is of growing interest mainly due to three factors: the global effects of the warming of the planet, the steady increase in the price of traditional fuels and the depletion of oil stocks.

Spanish law dealt heavily in recent years in promoting the reduction of energy consumption and emissions systems of heating of the buildings. To provide indications clear and appropriate parameters have been published several rules associated with an improvement in the insulation of buildings, higher levels of performance of heating systems and a significant increase in the share of energy from renewable sources. In this new environment, the use of radiant systems is highly appropriate.

Radiant Systems improve the thermal insulation thanks to the placement of tubes is done over a layer of insulating Deputy, guarantee Furthermore increased performance of heat emission and combine perfectly with solar energy systemsgeothermal and condensation boilers.

With regard to the improvement of the degree of isolation of the building, should be stressed that the implementation of an additional layer of insulation, in accordance with the laws in force, under the tubes through which circulates the hot (in winter period) water (during holidays) contributes to limit effectively the dispersions to below.

However, very often not is paid little attention to this measure in the use of other radiant systems as ceiling or wall, which have the same effect on the cladding applied, facilitating the rehabilitation of buildings in which for various reasons it is not possible to carry out interventions for improving the provision of energy.

With regard to emission performance, cannot be taken as a benchmark the data published in the regulation UNE-EN 15316-2-1: 2008

Radiant panels with isolation of the structure = 0.97.
Radiators with temperature of drive of 85 ° C in external wall insulated = 0.90.

These two simple data offer an idea of how the choice of the system of heating instead of the traditional systems already during the screening phase help the designer to achieve the value of minimum performance required by the regulations currently in force.

The following practical example attests to this. The value of average seasonal performance is obtained by each of the performance:

Ηp = production performance.
Ηr = performance of regulation.
Ηd = distribution performance.
Ηe = emission performance

Simulation of the example:

A system with caldera of condensation with regulation for setting type on-off, distribution with tube isolated according to regulations, radiators or, Alternatively, underfloor obtains the following results:

With radiators: 74%.
With underfloor heating: 80 per cent.

Obviously, in the second case to complete the ideal mode system would be needed a climate regulation with compensation curve depending on the external temperature expressly studied for the radiant systems, able to take full advantage of the characteristics of inertia of these systems to ensure optimal comfort and maximum energy savings. As mentioned previously, radiant systems work with temperatures very close to the parts that should be put up.

In winter the temperature of the water discharge is between 40 to 45 ° C, while in summer the values remain between the 19 and 17 ° C, approximately. This feature makes the radiant systems ideal for the use of renewable energy sources such as, for example, solar thermal energy or geothermal. Both systems can to maximize their potential if they are used in the winter with temperatures of drive not too high.

Solar thermal energy guarantees a good coverage for the least cold months and excellent performance in the less hot months; on the other hand, geothermal heat pumps always work effectively with very high coefficients of performance (Cop).

In summer geothermal heat pumps always kept Cop high and less hot periods get similarly temperature desired drive without the help of the compressor of the circuit of refrigerator, achieving a 'free cooling' operation.

In less hot periods or in buildings with low loads the desired drive temperature gets pushing water directly to the subsoil. thermal Exchange obtained through the temperature difference between water and subsoil is sufficient to satisfy the requirements of the heating system.

Classical conditioning systems can not enjoy this advantage because that will supply water to 7 ° C and in our territory the terrain reaches never as cool.

Increase of the living space

End customers especially appreciate the latter because they have a clear impact on those who need free space and for those who appreciate the distribution of the spaces from an aesthetic point of view. The heating system can be used both floor and wall or ceiling and does not require large spaces.

Radiant ceilings are gaining more and more followers because they are the ideal solution for buildings of commercial use and in open spaces; In addition, thanks to the low thermal inertia, adapt quickly to changes of thermal load or capacity. In the projection and realization of a radiant system must give maximum attention to the typology of the materials used and the system of regulation.

With regard to the tubes, should be always present its useful life and its capacity for resistance to brief peaks of temperature. In this sense, the most used material and providing greater guarantees of duration in time is the lattice polyethylene of class A, better known as PE-Xa. This type of material is particularly indicated with its long life and ease of manipulation that offers even at low temperatures.

With regard to the distribution manifold, the most commonly used for heating purposes are those of brass, accredited and with an excellent price/benefit ratio; cooling systems are however advised the use of polymeric collectors. This product reduces the formation of condensation during the holidays; in this sense for roof systems are those who get the best performance.

As previously mentioned, the regulation plays a crucial role in the installations of air conditioning and radiant systems are no exception in this regard. The regulation of a system of this kind should bear in mind the thermal inertia of the interior of the installation and present a high degree of sensitivity. Mainly for systems of heat transfer by radiation, a slight variation of the temperature of the surface corresponds to a difference of feeling by the user of the installation.

The regulation of heating systems, therefore, must be very precise and have always controlled all the parameters of operation, the temperature, humidity and time so that they can provide the maximum comfort and optimal use of energy in circulation.