Professional organisations and regulators
RICS- regulated practices:
Association of Building Engineers:
Society for the Environment:
Institute of Historic Building Conservation: 

Sources of information
Energy Saving Trust - free advice on energy conservation
CAT- Centre for Alternative Technology
SPAB - Society for the protection of ancient buildings
The Association for Environment Conscious Building (AECB)
Norfolk County Council guide "Making old buildings energy efficient":
Norfolk Historic Buildings Group: 
Earth Architecture and Conservation in East Anglia:

27 Richmond Place
Lyng, Norfolk

Tel 01603 879593