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Raising sustainability in Town Halls with Selectaglaze secondary glazing

Town halls are great examples of structures that require secondary glazing because they traditionally have to retain the external appearance of the building, due to Listed statuses. Well-installed secondary glazing is virtually invisible from the outside of a town hall and delivers the advantages of energy efficiency and noise reduction. It also offers an added layer of security and the internal finishes that can be achieved with secondary glazing are now of such a high quality, they can be a real feature of the overall interior design.  

The £22m refurbishment of Wiltshire’s County Hall in Trowbridge was undertaken to consolidate the majority of Wiltshire Council’s 95 offices into four hubs, reducing floor area by 50% and releasing 59 properties for disposal. 

A major requirement of this development was to reduce the energy consumption by 40%, making it the first refurbishment project within the UK with a BREEAM ‘Excellent’ rating, achieved by a complete building services overhaul together with improvements to the glazing and thermal upgrading of the walls and roof. The traditional single glazed sash windows were retained as an important architectural feature of the 1930s building and secondary glazing was chosen as a way of dealing with the both the heat loss through the glass and discomfort caused by drafts. Selectaglaze worked closely with main contractor Kier Western and Bristol-based architects Stride Treglown to develop appropriate designs to meet the thermal requirements but also had to be as unobtrusive as possible.

The solution for most windows was a matching balanced sash design that permits access to the existing window. Each frame is purpose made with high performance seals to reduce drafts and glazed with a low emissivity glass that markedly improves the thermal efficiency. Some of the windows were very large, up to 3.5m high and 1.6m wide, and a heavy-duty frame from the Series 90 range was required to support the glass sizes. Smaller windows were treated with a slimmer frame from the Series 20 range.

The need to be unobtrusive was particularly important in the timber panelled Council Chamber which has some of the largest windows. A single monumental hinged casement design was chosen as it permits an uninterrupted view through the windows. The Series 50 range was specified with a bronze anodised finish to complement the panelling. More than 270 bespoke frames were fully fabricated off-site allowing rapid installation to all four floors in phases to suit the contractors programme. The result is a more energy efficient and comfortable environment that is also much quieter

Joseph Aloysius Hansom’s 1834 masterpiece, Birmingham Town Hall, has been restored to its former glory. With a refurbishment budget of £34m, the 1830s iconic masterpiece has once more become the performance centre of the city. However, the journey from faded glory to world class concert venue was hardly straightforward and took the combined expertise and ingenuity of main contractor, Wates Construction and Selectaglaze.

The client was keen to retain the primary windows because they were the last remaining parts of the original building. The windows were very tall, with a casement of 4.5 × 1.8m, set 8m off the floor at the balustrade level. Also, they had to perform extremely well acoustically. Working with their tried and tested Series 50 side hung casement, Selectaglaze produced a unit which, at 4.5m high, was substantially taller than any previous construction.

Having met this first challenge, the next was how to fit the largest casement ever made, 8m up from floor level to cill. Working closely with Wates Construction, an ingenious combination of rollers, vacuum lifting gear and purpose designed scaffolding was identified as being the most practical way of positioning the windows so that they could be presented to the specially reinforced openings. The acoustic performance of the glazing combination and the fitting procedure also had to be tested on the initial prototype before manufacture and installation. Other necessary changes to the original Series 50 unit included the modification of the locking mechanism so that the unit could be closed by a single handle operated near the base of the window.

Established in 1966, Royal Warrant holder Selectaglaze has vast experience in working with all types of buildings throughout the UK. 

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