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Energy Conservation in Historic Buildings

Is your house wasting energy? While there’s no denying that some historic buildings are big energy users, they can be easily retrofitted to reduce the amount of energy they use and some may not use as much energy as you think! Because energy and heat were not as readily available when early homes were constructed, they were built to be as efficient as possible for the time. For example, deep overhangs provide shade in the summer, keeping the house cooler, yet allow sunlight and warmth into the house in the winter. Masonry walls are slow to heat up in the summer months, providing a cooler house. In the winter the walls absorb sun during the day, radiating the heat back into the house.


The National Park Service recently updated their guidelines for sustainably rehabilitating historic properties. New Secretary of the Interior's Standards for sustainable rehabilitations have been published, along with information about improving energy efficiency and new technologies that are compatible with historic properties. This information can be found online at:


Links to  general information about historic buildings, sustainability, and energy efficiency:


The way to determine exactly how your house performing is to conduct an energy audit. This will show where there are air leaks, how efficiently your furnace and hot water heater are working, and where energy use occurs in your house.

Here are some websites that can get you started on making your historic house green:

Once you have the energy audit results you can create a plan to improve energy efficiency. Start with the easiest and least costly, perhaps even doing some of the minor items yourself. Weigh carefully whether expensive changes will have the energy and cost savings you expect. Improvements that require changes to the historic features of your house—the things that make it unique—should always be last resorts. So before you take on the large and expensive project of replacing all of your irreplaceable historic windows, adding more waste to landfills, consider less intrusive measures discussed in the following pages.



How old is your furnace or boiler? Do you regularly change your furnace filter? If you have a steam or hot water system has it been regularly cleaned, drained, and maintained? Are the lines or radiators clogged? Are the radiators blocked by furniture or covers? Do the radiators have multiple layers of paint? All of these maintenance issues can contribute to an inefficient heating and cooling system, raising your heating costs and not providing the desired heat. Do you have a programmable thermostat installed? Installing this small item can reduce your heating and cooling bills by allowing you to program when the temperature raises and lowers based on when you aren’t home. How about your hot water tank? Do you drain it regularly to remove sediment that causes inefficient heating? Can you lower the water temperature so less cold water is needed for mixing?

In areas where heating ducts and pipes, as well as hot water pipes pass through lower temperature or unconditioned spaces consider insulating the ducts and pipes.

Here are some helpful links that explain more of these ideas:




Did your energy audit show that your house is airtight? Most heat loss occurs through the roof and around windows and doors that are not tight fitting. Additional air infiltration may occur around exhaust vents, through an open, non-existent, or ill-fitting chimney damper, and possibly through gaps in the sill plate, or around the roof and eaves. Air infiltration between conditioned and unconditioned spaces like an unheated attic can also lead to heat loss. Adding weather stripping to doors and windows will stop the drafts from coming through gaps between and below window sashes and under doors. Temporary, self-adhesive foam strips or more permanent types are available. It is important to eliminate air and moisture infiltration before installing insulation. Insulation will not work if it is wet, and does not necessarily stop all air flow. Adding insulation to the attic will stop the most heat loss because heat rises. Insulating crawl spaces and basement areas is also important. Some wall cavities may also benefit from adding insulation. It is VERY important to ensure you have a proper vapor barrier when installing any insulation to keep the insulation from getting wet and causing wood to rot. Consult a professional with experience in insulating historic buildings if you need assistance.

Here are some websites with additional guidance on insulation:




Popular advertising encourages homeowners to replace old, drafty, energy wasting windows the latest and greatest thermally efficient window product. Generally replacement windows are inappropriate for historic houses. Original windows are often one of the most important characteristics of historic buildings, and with proper weatherstripping and storm windows can be just as thermally efficient as new thermopane windows. Consideration should also be taken on the payback period of new windows, see the chart on the next page. So before you send your original, old-growth lumber windows to the landfill consider taking the following steps:

  • Install weatherstripping and caulking to ensure windows are tightfitting
  • Installing storm windows
  • Ensuring windows are in good repair - no cracked glass, intact glazing putty
  • Insulating sash pockets -- it can be done while keeping the sash operable

Here are some other websites to help you gather information about energy-saving windows:


 Reprinted courtesy of Old House Journal;

As you can see the improvement in U-values between historic windows with a storm are greater than two of the window replacement types above. Because new windows are significantly more expensive than storm windows the time it takes to recoup the costs through energy savings are longer than most people stay in a property.




 Do you dream of generating your own hot water or electricity—perhaps creating enough to sell power back to the utility company? As alternative energy moves to the forefront and new devices and technology are created, some of which may be appropriate for installation in the historic district. For example, new solar panels that look like roof shingles might be appropriate for installation on your asphalt shingle roof. Or you may have a roof that slopes toward the rear of your property where a more traditional solar panel may be installed.

Always be sure to get the approval of the City of Ann Arbor Historic District Commission before ordering any products or starting your project! The draft historic district guidelines provide additional guidance.

Here are some links to types of products currently available:


The information presented in these pages is just a sampling of the information available through the internet, libraries, governments and your contractor or architect.

As with any project it is best to get different opinions and costs to determine which is best for your historic property. Additional energy savings might not be house alterations at all—think about your landscaping, do you have deciduous trees that shade in the summer and allow sunshine in the winter? Do you have landscaping that’s water thirsty or grass that can tolerate low water conditions? How about your appliances, do they continually consume electricity even when they are off? It is important to maintain the integrity of the historic districts, but with some creative thinking it is possible to have the ultimate in sustainability—a re-used historic building that provides energy efficiency and comfort for today’s occupants.

Last updated: January 23, 2014

"Experience has shown that virtually any older or historic house can become more energy-efficient without losing its character" -- Richard Moe, National Trust for Historic Preservation


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