The majority of the units, which date from 1862, were 1.5m high with larger ground floor windows reaching 2.5m. Both frames and sashes had deteriorated and many were inoperable.
Ventrolla routed rotten timber out of the box frames and replaced that with its patented epoxy resin VR90. Bespoke slim double glazed windows were made to match the existing window profile and fitted into the renovated frames.
"Preserving the original sash windows was just as important as improving the energy efficiency of the building," a Ventrolla spokesman said.
The sash cords were replaced, pulleys serviced and sashes balanced to ensure smooth operation.
Military Academy project manager Andy Meachen said on the back of the work Ventrolla had been awarded the contract to work on its Old College project.
