This refurbishment project has produced a total of 133 "super luxury" short-term rental serviced apartments at one of the country's most prestigious addresses on London's Park Lane. This major internal reconfiguration and refurbishment, has retained many of the original features of this 1930s building, including all 600 windows. Acoustic trials demonstrated that double glazing could not provide the high levels of noise insulation required; the solution was to refurbish the sashes and compliment these with bespoke secondary glazing. The significant reduction in noise, elimination of draughts and much improved thermal insulation have all contributed to a comfortable environment for guests. Series 60 tilt-in units suitable for traditional sash windows with offset meeting stiles allowing a close fit to the primary window, were installed. Spring release catches allow sashes to tilt-in and "stay arms" safely hold the sash in the open position. To provide a very neat appearance all fixings are concealed within the frame.