EPACRA: Lanzadera project. Study of air flow patterns in radiating conditioning systems.

Effective period: 01/12/2015 - 01/06/2017
University: Universidad de Valladolid

Researchers:
        - Jesús Feijó Muñoz (UVa)
        - Alberto Meiss Rodríguez (UVa)
        - Miguel Ángel Padilla Marcos (UVa)

ABSTRACT
Currently, ventilation has become an essential process for human comfort inside buildings: it is known its impact on asthma, allergies and respiratory diseases by sick building syndrome and the decrease in general productivity when the indoor air does not have the necessary quality. Consequently, on the outside air (very hot in summer, very cold in winter) inlet, a lot of energy must be spend for conditioning, which has a very significant impact on the energy efficiency and sustainability: therefore, the use of a more efficient ventilation strategy is equivalent to reducing total primary energy consumption on ≈9% in the EU countries.

The various existing national regulations (in Spain, the CTE DB-HS3, Indoor Air Quality) often study the spaces globally, meaning it establishes minimum ventilation flows depending on its type, surface, potential pollution sources or number of occupants. However, even if those regulations are fulfilled in the enclosure, there may be areas inside who have a ventilation excess or deficit. Thus, the currently proposed systems are not efficient when it comes to supply air to those areas of the building that require it, even if they fulfil the regulatory minimum flow contribution.

It is therefore necessary to analyze the ventilation efficiency in detail: this procedure results in studies which allow optimizing the used systems and, by operating more efficiently, to achieve significant energy savings.

Together with the need to ensure air quality, it is necessary to ensure the thermal comfort of the enclosure user for obtaining comfort. This sensation will be related to parameters such as operating temperature, humidity and air velocity.

The concept of operating temperature acquires particular importance. As the rules state (in this case the Regulation of Thermal Installations in Buildings) on this notion, the concepts of dry temperature and radiant temperature are combined.

The traditional heating and cooling systems from modern architecture are usually calculated from the dry temperature parameter, but can not achieve human comfort (or energy efficiency) on their own. It is necessary to incorporate the influence of surface temperatures from the envelope that surround the studied space. Thus, it may be briefly recalled how this notion is present in our history: the traditional Glorias are based on radiant heating, as well as the custom of covering the thick stone walls of our castle in winter by tapestries.

The concept is that the human body perceives the temperature as a combination of these two parameters: air temperature from where you are and the wall temperature surrounding it (which emits thermal radiation). Therefore, planning radiant heating and cooling systems allow condition the air temperature inside the buildings energy reduction, which means huge energy savings, with comfort conditions even higher than the ones with current traditional systems (since the air velocity is very low and no annoying air currents are perceived anymore).

These radiant systems are already common in many of our buildings: radiant heating, cooling ceiling, radiant ceiling, etc. However, so far they have only been studied from the thermal point of view (temperature stratification, drafts, thermal comfort of the occupants) without incorporating how these affect the ventilation efficiency and how they affect in an attempt to reduce the air inlet flows entering from outside.

The methodology that is proposed will replicate different scenarios (the usual in our buildings) inside a test chamber. For this purpose, the Ventilation Laboratory facilities of the ETS Architecture School of Valladolid, built under a national research project (from the Ministry of Education and Science) will be used.

The facilities constructive system also allows studying the feasibility of implementing soundproof insulation solutions, so that the various processes will have their corresponding test. This solution would allow improving the acoustic performance of our buildings, according to the current regulation of CTE-HR.

Quantitatively, our former studies give the clue that it is possible to obtain up to 10% energy savings compared to other similar existing radiating conditioning systems.

Qualitatively, it is possible to state that a thorough study of the proposed system can establish design guidelines that involve a very significant improvement in thermal comfort, air and sound quality of the building users of Castilla y León, making it feasible to being materialized in lawsuits to be included in the tendering specifications for new works.

Finally, the proposed global optimization will directly impact on design, production, installation and applicant promotion systems, putting their work in value against the Swiss multinational to which it is associated.