A prefabricated, timber framed structure, a two-storey university extension of 1200 sq m, was designed and built to comply with a tight deadline, whilst meeting the budget requirements and combining environmental and energy efficiency. Single skin panels for the external walls were manufactured off-site, and consisted of 240 mm Masonite beams filled with Warmcel 500 insulation, with internal and external sheathings of 6 mm Paneline and 9 mm Panelvent, respectively. Space was provided for wiring and pipework which was then enclosed with standard plasterboard. The internal walls were 89 mm CLS timber panels, also finished in plasterboard. Construction required approximately two months less than the original masonry design, and reduced the requirement for skilled tradesmen. The energy required for production was 42% less than that for lightweight concrete block wall, whilst the high performance insulation, produced from recycled newspaper, virtually eliminated the need for heating.