Airtightness is critical to reducing heat loss and also preventing air migrating through the building fabric potentially leading to moisture damage. Steel frame was the only option to the upper floors to enable the large openings, but steel makes airtightness difficult. Pro Clima Aerosana is a liquid airtightness which can be brush applied and is much quicker and simpler than using tapes (and also easily allows the steel itself to be made part of the airtightness layer) thus providing significant cost savings. The (white) Aerosana is permanently flexible and can span gaps up to 20mm and the image shows joining the steel to the concrete and also sealing around the bolts.
