Designed by architects M. De Renzi and G. Pollini in 1938, the Central State Archive was part of the so-called Piacentini urban development plan and allocated to stand at the end of one of the three thoroughfares crossing Via Imperiale. Work began in May 1938 but was only partly completed in 1942. Today the building is a listed heritage site under the stewardship of Rome’s Environment and Architecture Authority. The complex comprises a central volume and two side wings. Access is via a monumental central staircase to the entrance. The main façades have a porticoed front topped by a loggia while the elevations overlooking the inner courts present a series of simple openings, their heights differing according to the storey. The extraordinary restoration work carried out on the eastern portion of the right wing involved the interior and complete replacement of the outside window frames. Even though considered of particular note by the heritage authorities, the original large, interestingly shaped iron window frames and the single-glazed panes did not meet current building energy-efficiency regulations. New window frames were chosen on the basis of aesthetics and compliance with heat-conductance standards. Aluminium profiles by Metra were chosen: Model NC 65STH in 6060 primary alloy, UNI EN 573 and UNI EN 755-5 compliant in physical state T5 as indicated by UNI EN standard 515. Called an “open-joint” system, the frame has profiles with a thermal break as required by UNI standard 10860. The central seal is placed behind the outer profile in such as way as to create an ample pressure-equalizing chamber. The fixed frame (depth: 65 mm) lies flush with the wall. The internally mounted sash is 75 mm deep. The glass panes “snap-fit” into their fastener profiles and are further secured with special hooks. The seals around the panes should be in appropriate EPDM, correctly fitted and joined at the corners. A continuous 27mm polyamide wedge eliminates thermal bridges guaranteeing thermal transmittance of 2.4 W/m2K. The double-glazing comprises a 44.1 clear laminated pane + gap 20 + 33.1 low-emissivity pane. The new frames resemble the original ones in shape, size and colour while the modern double-glazing is compliant with thermal transmittance regulations. The designers decided on aluminium frames on account of their high wear and weather resistance even without maintenance, and their excellent weight-solidity ratio. This allowed the replacement of the tall frames (average height: 6 m) on the first floor. Choosing an article that both complies with architectural preservation requirements and allows energy savings in terms of lower interior heating and cooling demands has contributed considerably to the building’s overall quality. This would not have been possible had iron frames like the original ones been used. Indeed, heritage authority approval of the change in material was dictated by aluminium’s notable energy efficiency and durability. The renovation project has placed this building on a technological par with its modern counterparts while enhancing its historic value as part of Italy’s architectural heritage. It stands as an excellent example of how modern technology can be combined with historic architecture.
