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Article Date: 5th April 2017

Selectaglaze - A Georgian Townhouse is Remodelled to Meet the Highest Energy Performance Standards

Georgian Townhouse - Passivhaus EnerPHit - Secondary Glazing System

Selectaglaze - John Street Window

A historic Listed Georgian townhouse in London’s Bloomsbury has been transformed into a comfortable, peaceful and energy efficient home that passes Passivhaus EnerPHit standards.

Modern insulation techniques achieved this, including an advanced secondary glazing system from Selectaglaze that remarkably improves the performance of the traditional, single glazed sash windows.

The client needed a low energy home that offered the most comfortable environment. Robert Prewett of Prewett Bizley architects convinced conservation officers that a Grade II Listed building could be successfully fitted with a host of energy saving measures whilst respecting all the historic features.

The large single glazed sash windows were a particular challenge as they represented a significant proportion of the wall area and could not be changed. The answer therefore was secondary glazing; but due to the high levels of insulation required, the aesthetics and the need for working shutters in certain rooms demanded a bespoke solution.

Selectaglaze - John Street KitchenTo begin with, Robert approached Selectaglaze and suggested a brand new design but coincidentally the company was both developing a new sash window design and trialling Pilkington’s Spacia thin vacuum units which have a centre pane U-value of 1.0. The resulting Series 25 window proved perfect for the project with its high sealing efficiency, a very low U-value and a discrete frame with a specially developed slide catch for shutters to fully close. Today, he house has air tightness close to 1 air change per hour at test pressure which shows that the secondary glazing is performing very well.

The difficulties of the project and the time required to receive consents meant that part of the building had to be occupied before the secondary glazing was fitted. Subsequently the owner experienced a great improvement in comfort levels offered by the original window and with the secondary glazing in place.

Selectaglaze - John Street BathroomThe difference was extraordinary and what was also clear was that road noise was almost non-existent. This was not addressed as a major issue but the absence of noise undoubtedly added to the cosiness.

Monitoring tests will now review the efficiency of the scheme over time but meanwhile there has been a transformation that delivers a modern comfortable home environment within an historic building.

Selectaglaze has fifty years’ experience working on all forms of buildings from heritage buildings to new build hotels. Selectaglaze works closely with clients so that their requirements are met to make buildings warmer, quieter and safer.

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