Adaptive heat transfer and sunshading for a fully glazed façade

A fully glazed facade is a facade which provides maximal advantages for buildings concerning daylight and view. Daylight reduces the energy use for lighting; view provides comfort and gives the possibility to experience the surroundings of the building. The possibility of providing solar entrance into the building has big influence on the reduction of energy consumption for heating in winter period. Applying a fully glazed façade requires necessary measures to control solar entrance in the building. Unwanted solar radiation results in a unwanted heating of the building, increasing the energy consumption for cooling. Unwanted light irradiation leads to discomfort due to overexposure. In the current design practice shading is applied in- or in front of the glazing. The shading (temporarily) outweigh the benefits of the glass surface. A permanent- solar controlling glass prevents the utilization of the heat of the sun in any situation. And an adjustable sun shading device in front of the window is keeping out the heat of the sun, but also keeps out the light and the view. For these reasons, also from an energetic point of view, the amount of glass in a façade is often limited. The façade concept researched in this study is a fully glazed façade that has the ability to shade without drastic reduction of light and view, and that optimizes the energy balance of the building. The facade has two positions: closed and open. The facade in closed position, is flat, vertically oriented, and offers the benefits of insulation and solar gain. When the facade is in open position, it is forward inclined and is creating shading as a result of the inclination. The change of position of the facade is performed by tilting the facade forward. The expectation is that this dynamic facade can provide energy savings compared to existing façade types. The purpose of this study is to calculate the resulting energy consumption of this dynamic facade. Also the façade concept is technical-practical elaborated. The main questions of the research are: What is the energetic performance of the dynamic façade, what is its best configuration, and which mechanisms play a role in the energetic result. The facade is proposed for an office with fully glazed facade. For the calculation of the energy performance, a detailed model of a standard office room and its façade is created. Existing façade types, used to compare the dynamic façade with, are the following conventional variants: - a façade with low g-value, a facade with outdoor blinds, a facade shading by geometry, and a façade with reduced glass area. The technical-practical elaboration of the dynamic façade answers the question of how the adaptable façade can be made in practice. This elaboration focusses on how an adaptable façade can be created while maintaining constant primary functions. The results of the energy performance calculations are the input for the technical elaboration. The method of the research is as follows: first the two static positions of the façade are modelled separately by means of dynamic modelling in TRNSYS. The two positions are combined in a dynamic model of the dynamic façade that is able to change position during simulation, depending on the desired comfort-temperature. The resulting values of energy use for heating and cooling of both the dynamic façade and the conventional variants are compared to each other. Researched is the influence of the properties of the dynamic façade on the resulting energy use. For various locations in Europe, the dynamic facade is compared to the best performing conventional variant(façade with external sun shading). This comparison makes it clear the locations of preference for the dynamic facade. Concerning the technical elaboration; by means of researching the separate elements of the façade, the concept is elaborated into a detailed design. Factors that are addressed are the material choice of the movable layer, the moving of a façade element and the combination of those factors into a façade system. Results are in favour of the dynamic facade. Following from the comparison with the existing types, the dynamic facade gives an energy consumption of a fifth of the best performing static variant. Applying night- cooling changes the advantage of the dynamic façade to a third of the best performing conventional variant. In this comparison the energy use for heating and cooling is used. To get a complete overview of the energy use, the influence of ventilation- energy, lighting- energy and motion- energy needs to be added in the comparison. During the period of the year where normally cooling takes place, the initial state of the facade is opened, and during the period of the year where normally heating takes place, the initial state of the façade is closed. During these periods the facade changes to another phase when the external climatic makes that the thermal comfort otherwise could not be guaranteed. Out of the comparison of the dynamic façade to the conventional, for other climates in Europe, the effect of the dynamic façade depends on the type of summer; locations with a hot summer, compared to locations with a warm summer are reducing the effect. Concluding, the simulated facade is focussing at exchanging heat by means of transmission. The elaboration of the façade is focussing on the combination of the two positions. In closed position the heat transmission is minimized, and in open position the heat transmission is maximized. To ensure constant basic functions of the façade, like water- and air- tightness, and sound isolation, a flexible movable layer with high mass is used. A foldable bellow principle is used to make this layer movable. The resulting façade system is a fully glazed facade with adaptive heat transfer and sun shading.