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Historical building in London’s financial district improved thermally with secondary glazing


Selectaglaze has recently worked on an impressive building in Moorgate Place; midway between Moorgate and Copthall Avenue in Central London. It was built in the 17th century by the Clothworkers Livery Company, replacing a cluster of smaller buildings. Originally known as Coleman Street Buildings, it was renamed as Moorgate Place sometime in the 19th century. The layout of the buildings in this area is attributed to early developments in the Saxon and Norman periods. Now in 2022, Moorgate Place is in the heart of London’s financial district; a unique part of London and an important slice of English history.

As part of a substantial refurbishment spearheaded by architects TP Bennett, with works carried out by main contractor Overbury, Selectaglaze was approached to explore secondary glazing solutions for the main purpose of thermal insulation across all floors of the building. At one point, secondary glazing was value-engineered out of the scope of works. However, it was assessed that the extra equipment and associated cost of mechanical and electrical works to enhance the heating and ventilation system, was far greater than installing secondary glazing, which would provide the same benefits, so it was re-introduced into the plan.

Well-sealed secondary glazing will regulate temperature and help lower energy consumption. By improving the energy performance of an office building, it can contribute towards a higher rated Energy Performance Certificate or an improved BREEAM rating. An extra advantage of the seals incorporated in the secondary glazing is cleaner air through the reduction of airborne dirt and dust from outside. Furthermore, Selectaglaze secondary glazing fitted with a 100mm cavity will reduce noise levels by a certified 45dB or more and create the quiet internal space needed for productive work.

A total of 289 secondary glazing units were installed across all floors in the building; in open plan office spaces, elevator lobbies and a reception area at the entrance, the majority of which were Series 20 vertical sliders. With its slim profiles, it is perfect for treating traditional sash windows, an ideal match for the existing fenestration. A minimum frame to frame gap of 75mm is recommended to assist cleaning, especially near the meeting style/interlock. The sashes contra slide to help with cleaning and allow for access to the primary window.

The only difference in the secondary glazing specification was on the ground floor. Here, several tall Series 20 vertical sliders were installed with Series 31 lift out units coupled above them as the ceiling had been raised. A horizontal sliding system could have been used here as another treatment option, but the client preferred to remain consistent with the units on the upper floors and have, where possible, the same secondary glazing product throughout. Also, on the ground floor was a newly refurbished reception area with two large curved primary windows on either side of the front entrance. Six Series 46 curved fixed light units were specified for these windows as it has a very slim fixed frame that can be shaped and curved to a full circle if required.

The successful installation of secondary glazing will enhance the working environment, for the new occupants on each floor, with a significant difference in thermal retention, draughts virtually eliminated and improved energy performance. It will also ensure the working environment across all the office floors will be more peaceful. Overbury have been impressed with how well the secondary glazing is performing and have already noticed how much warmer and acoustically efficient the building is.

“Selectaglaze worked with Overbury and TP Bennet during the design phase to maximise both the thermal and acoustic properties of the existing building envelop to enhance the building to meet modern standards. Selectaglaze was very helpful during this stage and surveyed all the existing window openings. The programme was phased with 2 floors being installed together and each phase 3 weeks apart. The site guys were very organised and snagged their own works as it was installed so there were zero defects at the end of the project. I would have no hesitation in recommending Selectaglaze for future projects.” Comments Bob Squires, Overbury Senior Project Manager

For further details, visit: www.selectaglaze.co.uk, T: 01727837271, E: enquiries@selectaglaze.co.uk

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