ENEA

Panel for variable transmittance wall

“Responsive” perimeter walls, adaptable to different outdoor or indoor climatic conditions of use, by means of components capable of varying the thermal insulation properties of the building envelope (thermal transmittance).

Patent Status

PENDING

Priority Number

102018000003193

Priority Date

01/03/2018

License

ITALY

Market

The target market is the construction market related to new construction, including urban regeneration interventions with demolition and reconstruction, and to renovations where demolition of perimeter walls may be important if not necessary. An assessment of the potential stock of existing vertical perimeter walls of interest for energy upgrading (CRESME-FIVRA -2014) is 5,049 Mm2 of which 4,140 are residential. For new construction, the annual potential for vertical walls according to the same study is 25.8 Mm2/year, of which 16.8 residential. In the four-year period 2016-19, the interventions carried out under the incentive of tax deductions for energy upgrades of vertical walls covered an area equal to an average value of 2.83 Mm2/year. An acceleration can also be expected in the coming years as a result of European and national policies to reduce primary energy consumption in both the residential and tertiary building sectors. Europe-wide, an estimated 210 million buildings, 40% of which were built before 1960, are in need of major energy upgrades.

Problem

The energy performance of a building depends on the thermal characteristics of the perimeter walls such as conductivity and thermal capacity. Reducing thermal conductivity allows a reduction in winter heat loss to the outside and at the same time a reduction in thermal reentry in the summer period. Such walls, however, generate in the summer period the tendency to:

an increase in thermal energy needs;
an overheating in the presence of internal loads;
an increase in the duration of the cooling season.

The cause is related to the difficulty of such walls to cool down at night or generally during periods when the outside temperature is lower than the inside temperature.

Current Technology Limits

At present, the improvement of the summer behavior of the wall is achieved by structuring the wall in order to obtain high values of the thermal phase shift and/or low values of the periodic thermal transmittance. Another possibility is offered by the use of ventilated facades that reduce solar loads acting on the wall through a screen placed on the wall. However, the need to reduce primary energy requirements for building air conditioning is leading to the development of new technologies in a highly integrated context, characterized by being “adaptable” to various uses and with varying physical or efficiency characteristics depending on outdoor and indoor conditions.

Killer Application

With the patented panel, multilayer perimeter walls can be built according to dry/wet methods in order to make the behavior of the wall “responsive” (RBE – Responsive Building Element), i.e., adaptable, to outdoor and indoor climatic conditions by making the thermal transmittance variable. The adoption of perimeter walls with variable thermal transmittance for building envelopes can significantly reduce primary energy consumption for cooling while retaining the optimal characteristics for winter operation.

This provides an innovative solution for achieving a reduction in primary energy consumption in the building sector, both residential and tertiary, for new construction, urban regeneration with demolition and reconstruction, and major renovations involving the demolition of perimeter walls.

Our Technology and Solutions

The patented panel makes it possible to build multilayer perimeter walls (panel coupled with other insulation layers, PCM, emission system, interior finish, even pre-assembled) according to dry/wet methods in order to make the behavior of the wall “responsive,” i.e., adaptable to outdoor and indoor climatic conditions. Such a wall significantly reduces the building’s primary energy demand.

The control system can, in addition, be easily implemented in common home automation control systems already widespread in the market.

Advantages

With the patented ‘responsive’ wall, it is possible to make the thermal transmittance value variable by allowing:

to have low transmittance values in winter while ensuring high insulation values;
high transmittance values in summer when outside temperatures are lower than inside temperatures, ensuring natural cooling of the building;
high transmittance values in situations of use with high internal loads in mid-season, ensuring natural cooling of the building. The wall realised with the patent artefact has a responsive and controllable behaviour depending on climate (external temperatures) and use (internal temperatures and loads);
to significantly reduce primary energy consumption for cooling while retaining optimal characteristics for winter operation.

Roadmap

Experimental results from a proof-of-concept project confirmed the performance and ability to achieve a wall with variable thermal transmittance. The Technology Maturity Level of the technology reached a TRL 4, with the realisation of the prototype perimeter wall and its validation of its functioning in the laboratory. A panel with significantly increased exchange coefficient performance compared to the starting panel was developed and tested. The operation of the panel was also tested with the use of home automation type ventilated control systems. Tests with massive walls and/or pcm have not yet been carried out. Continuing the activities with the continuous operation of the prototype in the operational environment, it is plausible to achieve a TRL 7.

Potential players with whom to develop the technology are manufacturers of semi-finished and prefabricated components for the construction of perimeter walls (including particular manufacturers of insulating panels in combination with them and in the various implementations envisaged by the patent) and manufacturers of prefabricated walls for the construction of new wall configurations.

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Team