As historic property homeowners or renters, we are stewards of history and as such should try to maintain the architectural integrity and authenticity of the exterior of our houses for future generations. There are several resources available that provide guidance to improving energy efficiency in historic houses.
First, the City of San Antonio Historic Design Guidelines has these suggestions:
Insulate buildings using minimally invasive techniques to improve energy efficiency. Appropriate insulation techniques vary based on the type of construction and should be selected in consultation with a contractor specializing in historic home maintenance. Moisture problems within the wall cavity should be addressed prior to adding any sort of insulation. Blown in insulation may retain entering moisture, ultimately leading to rot and decay.