Heritage & Timber
With 8.3mm LandVac vacuum glazed units , the Winston Heritage sash window delivers a whole window U-value of 1.12W / m 2 K and the Richmond flush casement offers a whole window U-value of 1.20W / m 2 K for a standard industry sized window . These values become even lower as the windows increase in size .
The range has ultra slim frames suitable for period properties , which are made from Accoya ®, a sustainable Class 1 durability rated acetylated wood , which requires minimal maintenance , has low life-cycle costs and a 70-year minimum service life ( TRADA ). These frames are protected by a specially formulated micro-porous paint system and the whole windows require no maintenance for their entire 10-year warranty period .
Other modern performance features include fully concealed gaskets and a patented sash sealer , neatly hidden within the joinery , which is shown in BSI testing to improve the air permeability of a sliding sash window to Class 4 standards . A traditional putty-line , replicated in the outer profile also significantly improves the windows ’ security and coating longevity . Amongst its many
Mew House deep retrofit – a case study .
The potential of the Heritage range to significantly advance building conservation is demonstrated in the retrofit of Mews House , a low energy Victorian listed mews property in West London , which won a 2022 RIBA Regional Award and 2022 AJ Retrofit Award for best house >£ 500k .
The renovation of this traditional carriage house , originally built in 1878 , shows how ‘ deep sustainability ’ can go hand in hand with building conservation and traditional craftsmanship .
Architects Prewett Bizley aimed to completely remodel the interior into an inspirational lightfilled open plan living space , enhance its external appearance within the local conservation area setting , and to drastically reduce the carbon footprint to better than that of a newly built home .
The replacement of the existing single glazed windows with Gowercroft ’ s Winston Heritage Sliding Sash windows was central to meeting both sustainability and conservation objectives .
To secure planning permission , the architect required higher performance levels than could be achieved with conventional windows , including superior thermal efficiency , longer life expectancy and a traditionally crafted timber aesthetic just like the original ‘ multi-pane ’ windows . A total of 16 Winston sliding sash windows of varying sizes were installed .
The air tightness of the frames , with Gowercroft ’ s sealing system ,
traditional features Gowercroft offers slender 18mm glazing bars , plus period ironware .
This ground-breaking combination of period detailing , modern materials and market leading performance has led to the Heritage range being recognised in several national industry awards including winner of the 2017 Build It Award for ‘ Best Window ’; finalist in the G18 Awards ’ for Best new product ’; winner of the BWF Awards ‘ Woodworking Project of the Year ’ in 2019 and for ‘ Heritage Project of the Year ’ in 2022 . contributed to a very impressive air tightness close to 1 m 3 / m 2 hr at 50Pa , which is exceptional for a property like this .
The Winston Heritage sliding sash window has been assessed using the BRE LINA LCA tool and has been demonstrated to deliver exceptional long-term sustainability . The Cradle to Gate embodied carbon of the Winston Sliding Sash in an industry standard size is 92.70 kgCO 2 eq ., and the Cradle to Grave embodied Carbon is -10,019.29
kgCO 2 eq . due to the exceptional thermal performance , long life span , and low maintenance requirements .
Recognised as a landmark in heritage retrofit , the Mews House achieved a massive 82 % measured reduction in the overall energy consumption ( from 325 to 51kWhr / m 2 yr ). The replacement sash windows were central to achieving this , from both a thermal efficiency and weather-tightness point of view and , remarkably , its current measured energy use is less than 2025 RIBA targets for new build houses .
The shape of things to come .
As the UK moves towards its net zero targets by 2050 , Gowercroft ’ s Heritage windows represent an enormous leap forward . Further products have been added to the range to ensure complete coverage for all historic buildings , these include the Clement Hopper window , Belton Horizontal sliding sash window , Churchill single , French and stable doors and the Halifax bifolding door .
www . gowercroft . co . uk
CLEARVIEW-UK . COM OCTOBER 2023
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