Located on Parliament Square, opposite the Houses of Parliament, is the UK's first Supreme Court; which is now in a Grade II Listed building. One key objective for the refurbishment was to achieve BREEAM rating 'Very Good' which required significant improvement in the thermal efficiency of the windows. The external windows could not be modified hence secondary glazing was used. The use of low emissivity glass within the secondary window lowers the U-value to below 2.0. Sound insulation was equally important for the proceedings of a Court. Glazed windows with a thick laminated glass can reduce noise levels by more than 45dB and markedly improved the security of this sensitive building. The project required 450 separate window frames ranging from hinged casement, vertical sash, fixed and horizontal sliding to treat the wide range of window styles. This included a significant number of gothic arches and three large shaped acoustic screens between the public gallery and Courtroom 3.