I just bought a 1900s brick row home in Harrisburg, Pa in historic district.  I need a contractor who can retrofit energy efficient systems but does so preserving as much historic detail as possible.  Can anyone suggest where I can go to find such a contractor?
City requires work preserves exterior historic character of buildings – replacement windows must appear as original – wood, not vinyl, for example.  Another example: if the large double hung picture window on the first floor may not be replaced to preserve historic nature, I need designer/contractor who can specify and install appropriate techniques & materials.  Other issues: How best to air/thermal barrier to the 3rd floor ceiling below the flat roof?  Same with 3rd floor dormers peaking out of mansard roofs?  Replace baseboard electric heat and add air conditioning.