A methodology for retrofitting of facades, via the addition of single- or double-glazings, has been developed in order to improve both the energy-performance of an existing building envelope and occupant comfort. This process of retrofitting is executed from the inside of the building, when the building is in use and with minimal disturbance to occupants. It also requires minimal intervention from the facilities team of the building, and does not involve de-commissioning of an office space during the retrofitting process. As such, this methodology of retrofitting is simpler and cheaper to execute when compared to the traditional method of re-installation of a new glazing from outside the building with/without- dismantling the existing glazing. The retrofitting solution has been launched at the pilot-scale for retrofitting office spaces, and estimates of the heat-ingress through the glazings demonstrate energy savings of the order of 50%. Pre- and post- retrofit evaluation of the occupant thermal comfort in an office space, as quantified using spatial distributions of the operative temperature, reveals a significant improvement in the thermal comfort of the space close to the facade. Depending on the time of the day, the drop in the operative temperature is found to range from 1.5 to 4 oC at workstation locations closest to the façade. Additionally, significant improvement in the acoustic comfort is also noted, and the peak noise levels, measured close to the façade (inside the building), are seen to drop from 60dB for the pre-retrofit scenario to 39dB for the post-retrofit scenario.