Hotel Indigo located on the edge of the Square Mile, is a four star hotel, part of the worldwide InterContinental Hotels Group. Occupying what was formerly an office building and bank, conversion to a boutique hotel and restaurant was a major architectural and interior design undertaking. As part of the conversion it was decided to replace the windows with double glazed frames but standard double glazing does not provide the levels of sound insulation required by guests. The solution was to install secondary glazing, thus creating triple-glazing which offered noise insulation in excess of 45dB and further improved the energy performance of the window, reducing heating costs and improving sustainability. The secondary windows were made bespoke to ensure the best fit and included horizontal sliding, vertical sliding and hinged casements all finished in a grey powder paint to blend with the new external windows.