Timber window manufacturer Mumford & Wood says its eco specification sliding sash windows achieve an “A” energy rating using the British Fenestration Rating Council (BRFC) energy analysis tool.

The Tiptree-based company said its standard frame sliding sashes with a width of at least 1300mm and more than 2.15m tall for use in new build, renovation and refurbishment projects would meet the BRFC “A” rating.

The company’s standard specification for its vertical sliding sashes includes a 4/14/4 double glazed unit using a low iron/low E glass combination with a 90% argon gas fill.

“Premium quality developments and prestigious renovations all take VSS units at least 2.15m tall,” said technical director Mike Harris.

“The ‘A’ rating at this size and above provides customers with the highest possible combination of thermal performance, operational efficiency and recognised aesthetics.”