Objectives and Problems to be solved:
The efficient use of daylight in buildings should provide different, contradictory functions concerning light and climate like illumination, redirecting, sun shielding, glare protection, contact to the outside environment or utilisation of solar thermal energy. The state of the art is to use a combination of several systems where each system is optimised for a certain task. Such systems are expensive and require complex constructions and big maintenance efforts. Standard control strategies are not available. Additionally the dominant influence of these systems on the appearance of the facade and difficulties concerning the technical integration in the facade tend to be an obstacle for their utilisation. So a system that integrates all these different functions in the glazing is far beyond the current state of the art. The electro-optical properties of liquid crystals are well known for usage in LCD's, but their use in fenestration systems is more recent. It is possible to combine the mechanical properties of polymer films with the electro-optical properties of liquid crystals and thus to produce liquid crystal films that can be used in daylight systems. The usable liquid crystal technologies are rapidly growing and some offered possibilities (such as colours, grey levels, progressive variation of optical properties in different localised parts of the glazing) are not yet integrated in the glazing field.
Description of work:
The goal of the research project is the development of a multifunctional daylight system which is able to control simultaneously light and climate.
The main idea is to use a specially designed movable lamella system embedded in insulation glass and to integrate layers with electrically controlled liquid crystals in this system:
-The insulating glass with incorporated mechanically adjustable lamellas provide a perfect integration in the facade with all the assets of this approved technology.
- The electrically controlled liquid crystal film offers the possibility to change the optical properties (transmission, reflection, scattering) of the lamellas.
- An intelligent control optimises the synergetic effects between the lamellas and the liquid crystal layers.
Aimed technical data of the LCDAYLIGHT system are:
- Total solar transmittance (g-value) 0.10 < g < 0.60
- Thermal transmittance (u-value) 1.1 W/m²K
- Internal luminance 200 cd/m² < L < 2000 cd/m²
- Diffuse light transmittance 0,05 < < 0.75. The LCDAYLIGHT system should be adjustable between these values using intelligent control strategies. This can be reached and electrically controlled by a combination of movable lamellas with layers of liquid crystals.
Approach and Expected Results:
- Definition of quantitative factors as above
- Geometrical and mechanical parameters of lamellas, simulation and evaluation
- Geometrical and electrical parameters of the LC system, functionalities, evaluation- Lamella/LC compound - geometrical, electrical, gradient, colour, mirror parameters and factors, LC deposit on lamellas
- Studies of a first LC/Lamella system, strengths and weaknesses- Prototype
Funding SchemeCRS - Cooperative research contracts
83160 La Valette Du Var