Re-LOOP TRANSPARENCY

Abstract

Glass is one of the oldest building materials used in the building envelope. Its attractiveness to architects, designers and users is mainly due to its fascinating ability to combine two otherwise contradictory functions; to separate and protect the interior from the exterior environment while at the same time allow for openness by letting daylight penetrate the space.

Apart from the apparent and basic function of transparency, glass, if properly designed, can fulfill almost any role in a building structure, from insulating a facade, to taking building loads besides its own weight and the imposed wind forces. Especially in terms of a building’s thermal performance, the assembly of single glass panes into insulated units is a colossal advancement for the building sector towards more sustainable structures since it allows the creation of fully glazed facades with minimised thermal losses.
However, the use of insulated glass units while improves greatly the energy conservation of glass buildings, it neglects to account for the impact of this assembly procedure on the waste streams the materials used create once their service life is over. Currently, there is no provision for extending the life-time of IGUs by the means of reuse, refurbishment or recycling and consequently they end up being discarded in landfills after a limited time of use.

For this reason, it is crucial to design an alternative IGU that abides by the laws of circularity, meaning the use of design approaches with an end-of-life plan for new products used as construction elements. Such a circular approach could greatly benefit the transition from a linear to a circular economy which is indispensable for the building sector since it accounts for a large amount of construction and demolition waste that end in landfills every year. The pollution from these wastes could be significantly reduced if the products applied were initially designed to be used in a circular way instead of having a single-life character.

The current master’s thesis focuses on the exploration, through detailed design, of the different ways in which an insulated glass unit can become more circular without compromising its transparency. The term circularity here refers to a design that tackles the end of life of the unit by facilitating its remanufacture in case its thermal performance starts decreasing; the reuse of parts of it or of the whole unit, and the recycling of the glass panes when neither reuse nor remanufacture are an option. Moreover, the aim is to create an IGU that is as transparent a possible by minimising the optical result of the current IGU edge seal connections.

In order to create a circular IGU, firstly, contaminating factors on the glass surfaces that could hinder their recylcability should be avoided. Secondly, a reversible way of connecting the different glass panes that comprise the IGU is opted for. Currently used IGUs have edge seals that consist of an element called a spacer bar and sealing elements that ensure the structural stability of the unit and prevent the air and moisture diffusion to the cavity. The element that connects the glass with the spacer bar in the current IGUs is a strong structural adhesive of black colour that cannot be removed without contaminating the glass. This is precisely the element that this thesis aims at replacing through an alternative connection design that enables the reversibility of the unit and the reduction of the optical impact of the edge seal.

The design exploration phase led to a final design that achieves the initial goal using an innovative alternative connection that replaces the spacer bar and secondary seal of a typical IGU with two cast glass elements each fused to the edge of the float glass panes. The connection of these cast glass elements occurs with the use of a simple mechanical clamping element, a metal spring clip that can be easily applied and just as easily removed. The small dimensions of this clip and its application internally between the float glass panes ensures the reversibility of the edge seal as well as its improved optical result.

The final design remains in a research stage proposal and further testing would be necessary regarding its thermal performance, its structural rigidity and the assurance of its good weather sealing. However, this research through design exploration concluded to a feasible, in theory, design that achieves the initial goal.