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.

Retain awnings to reduce heat gain from sun exposure. (Commercial properties)

Add UV film to windows to reduce solar gain on south and west facing façades, but avoid tinted or mirrored films. 

Second, the Internet has a mass of information plus blogs, list serves and online message boards that can provide personal experience of what has or has not worked.  In a blog by Sean Shanely (blog.wegowise.com/2014-02-12-which-retrofit-to-choose-windows,-insulation,-or-new-hvac), Sean likened changing out old windows to energy efficient windows to putting on sunglasses - they provide temporary relief but do not fix the problem by getting rid of the sun.  Replacing old single pane glass to double pane windows provides maybe a maximum “R-4” value.  Installing insulation in the walls, attic or foundation is like putting on a hat, coat and shoes.  Depending on how and where the insulation is installed you get from an “R-13” to “R-38” value.  The higher the number, the greater your energy savings.  

Researching the net can be very beneficial but remember, before you invest any hard cash in your project, check with the Office of Historic Preservation to get their advice and approval.  Every project, whether in a historic house or not, should get a permit from the City of San Antonio!

- Cherise Bell

Additional Resources

CPS Energy Rebates - www.cpsenergy.com/en/my-home/ways-to-save/rebates-rebate.html

The Secretary of the Interior’s Standard for Rehabilitation & Illustrated Guidelines on Sustainability for Rehabilitating Historic Building - nps.gov/tps/standards/rehabilitation/sustainability-guidelines.pdf

Improving Energy Efficiency in Historic Buildings, Preservation Brief #3, by Jo Ellen Hensley and Antonio Aguilar - nps.gov/history/hps/tps/briefs/brief03.pdf  

Energy Efficiency, Technical Preservation Services, National Park Service - nps.gov/tps/sustainability/energy-efficiency.htm  

Preservation Green Lab, National Trust for Historic Preservation