Deloitte Tower uses Technoform for energy efficient glazing

In order to control heat gain and loss, the glazing in the project is made up of dual pane insulating glass units (IGUs) with a low emissivity (low- E) grey colored coating on the inside surfaces.  The glass supplier and fabricator of the IGUs was Multiver Ltée of Quebec. Throughout the planning and design process, they assisted the architects with performance calculations, color selection, and other support. They recognized that the total performance of the glazing would be influenced not only by the glass itself but by the individual products that held the dual panes together, commonly referred to as glass spacers. Numerous independent tests and certification organizations have confirmed that selecting an inferior glass spacer results in the edges, as well as the center of the glass, performing poorly in terms of heat transfer.  If the seal along the edge of the spacer does not hold up, then air and water vapor can seep into the glass space otherwise filled with an inert gas. When that happens, the glass appears streaked or stained on the inside and performs even worse.

Further, in cold climates like Montreal, condensation can form on the inside of the glass along the cold edges causing other problems for the building components nearby.  Together, the architects and Multiver researched and chose glass spacers manufactured by Technoform since they met their design criteria for both excellent energy efficiency and the ability to meet unique aesthetic requirements. Specifically, they selected a 17/32” (13.44mm) TGI®-Spacer in a light grey tone to match the glass color beautifully.

Epsylon Concepts, Ltd. of Quebec, Canada designed, engineered, manufactured, and installed the curtain wall system. Epsylon is known as a leader in specialized high energy efficiency curtain walls making them ideal to meet the demands of the Deloitte Tower project. They also conduct an evaluation of all their products in regard to LEED certification for materials and vetted all products for compliance with the LBC “Red List” of 14 potentially toxic substances.  Because of the size and expanse of the curtain wall system, a pre-fabricated, unitized system was quickly determined to be the best choice.  Generally, these systems are used on mid-rise to high-rise structures that are 20,000 square feet and up where there is high repetition, tight job site access, and high installation labor costs. These systems hold up over time better than others because each curtain wall panel is installed to be able to expand and contract independently from the supporting structure and retain its ability to be completely weather tight.

The design team next considered traditional curtain wall systems compared to structural silicone systems. Traditional curtain wall systems use continuously gasketed aluminum pressure plates or caps that can conduct large amounts of heat in or out of the façade resulting in “thermal bridging”. Structurally glazed curtain wall systems consist of glass that is bonded or anchored back to a frame with engineered silicone sealant that can reduce or eliminate the thermal bridging along the joints between adjacent IGUs. The aesthetic benefit of a structural silicone glazed system is the creation of greater transparency than traditional systems.  There are less visual interruptions due to the lack of metal on the exterior, creating a seamless, continuous glass look. This system creates a completely clean, flush exterior appearance with superior energy performance. It can also be much more technically complex than a traditional system so the skill and quality control of the Epsylon team was heavily relied upon. 

The structural silicone glazed system selected was Epsylon Platinum Series 60.075 – 2S which is the highest performing curtain wall offered by Epsylon Concepts, Ltd. It is a pre-fabricated, unitized system, with structural silicone on 2 sides that allows multiple glazing types and materials to be combined into one ‘unit’ in a quality controlled shop environment. Precision is needed in sealing the units together since there is no outside metal frame to cover any irregularities or imperfections. That goes for the glass spacers used too, since in some cases they can be left partly exposed and create an unintended visual appearance. The TGI®-Spacer used in this project extends the colored polypropylene through an extended sidewall ensuring minimal opportunity for stainless steel peek through and overcoming this common quality control issue on structural silicone glazed units.  After the IGUs and spandrel glass are glazed into unit frames within the shop, they are transported and installed at the job site by crane.  The installed units then receive additional silicone and or EPDM gaskets on the exterior creating “stack joints” as the complete air and moisture barrier of the system allowing a weep at each floor.