As part of a major refurbishment to a large, detached Victorian villa in Hastings we have been involved in the manufacture and installation of doors and windows which have incorporated the use of a new concept in the construction of double glazed units -14mm krypton filled double glazed units. These units can achieve better levels of thermal efficiency than single glazing whilst maintaining the aesthetic integrity of traditional windows by maintaining slimmer section sizes in the construction of the window. When glazed, the units are virtually undetectable and would, therefore, be suitable for buildings in Conservation areas or Listed Buildings.