Preservation and sustainability. What does one have to do with the other? If we examine these terms more closely, we can see that older buildings are inherently “green” or sustainable because of “embodied energy” (all of the energy used to build the building that would need to be expended to build something else). In fact, the report from the National Trust for Historic Preservation “The greenest building” states:

“This study finds that it takes 10 to 80 years for a new building that is 30 percent more efficient than an average-performing existing building to overcome, through efficient operations, the negative climate change impacts related to the construction process.”

This statement about life cycle analysis indicates that the construction process is resource intensive (both in production and transportation of new materials and landfill debris – about 20%-25% of landfill waste is construction-related). Reusing an existing building is the ultimate recycling, so preservation and sustainability are often inextricably linked, and this link highlights the importance and value for sustainability inherent in preservation.  


Photo by Random Institute on Unsplash

 

PRESERVATION’S LINK TO SUSTAINABILITY

Not surprisingly, both the preservation and the “green”/sustainable initiatives have significant common ground and can work in concert with one another. This is particularly relevant in light of concerns regarding climate change and major environmental concerns. The National Trust for Historic Preservation formed the Preservation Green Lab in 2009 to strengthen the connection between preservation and sustainability, and updated the name to The Research and Policy Lab in recognition of expanded needs. The National Trust for Historic Preservation has increased focus on climate change impacts on our heritage. There is also an International Climate Heritage Network to address the intersection of climate change and other environmental disasters on arts, culture, and heritage.

However, at times in the recent past, green and preservation agendas have been at odds and there has been a bias in the sustainable building field to start over with new buildings and materials, as pointed out by Tristan Roberts, and The Washington State Department of Archaeology and Historical Preservation’s (DAHP) Sustainability and Historic Preservation Executive Summary from 2011. The Whole Building Design Guide’s Historic Preservation Subcommittee (WBDG) notes that there has also been a stigma attached to preservation and it has been (often inaccurately) labeled as inefficient and requiring overwhelming or costly procedures to retrofit energy efficient systems into old systems. Additionally, Roberts reports that certain sustainable products that are made of recycled content or other sustainable materials may not be approved by the National Park Service’s Secretary of Interior’s Standards for Rehabilitation simply because they disrupt a building’s character-defining appearance. However, preservation and sustainability are far from being mutually exclusive. As Roberts reports:

“Both the environment and cultural heritage suffer when buildings are treated as disposable.”

Below, we outline characteristics of preservation that lend themselves to sustainability:

  • Energy Efficiency. As noted earlier, it also takes less energy to maintain or rehabilitate an existing building than to demolish an existing building to construct a new building, even if that new building is “green.” Restoration involves less carbon emissions than new construction. Comparatively, DAHP noted in 2011 that new buildings accounted for 40% of all extracted energy sources and 68% of all consumed energy per year. DAHP also cited the U.S. Department of Energy (DOE) who shared data indicating that “commercial buildings constructed before 1920 actually use less energy per square foot than buildings from any other decade up until 2000.” New buildings made of new materials means one must consume energy to both create and ship those materials, and this also contributes to carbon emissions. DAHP adds that many historical buildings were designed with “passive systems,” or systems that took advantage of things like natural light, ventilation, and solar orientation when electrically-powered options did not exist. These passive system characteristics are all inherently sustainable and meet the same “green” goals of the sustainability camp. You can read more of our articles on energy efficiency in our archives here

 

  • Durability and Waste. Preserving a historical building reduces consumption of materials, and retaining old material creates less construction landfill waste. Green buildings should have materials that are both durable and repairable, whether that green building is new or old. Many new green building products are durable, but not necessarily repairable (read our repair archives here). Additionally, to build a new building with new materials, you have to create and ship the resources (both of which take energy), and often they are placed on newly cleared land which takes energy but also may be removing resources such as forest or farmland. Rehabilitating an existing or historical building eliminates a lot of these issues. Even reusing durable, salvaged materials from buildings that are torn down keeps those materials out of landfills and provides green materials for another building. However, more wasteful decisions are perpetuated, as Roberts points out that the construction industry often falls prey to “short-term thinking,” focusing on what works in-the-moment and disregarding long-term outcomes. Despite these benefits of preserving or rehabilitating older buildings, there can be challenges related to durability and waste in older buildings. Roberts notes that not all older buildings were well-built with durable material or construction, so in some cases, building damage is not due to neglect or abuse, but the way the building was constructed (e.g., some buildings with structural steel that is corroded cost a lot to repair). Further, as more modern buildings age and qualify as “historic” each year, these sometimes less durably-built structures pose new challenges for both the preservation and sustainability movements.

 

“GREENING” YOUR HISTORICAL COMMUNITY, BUILDING, OR HOME

Several efforts at the international and national level have been highlighted here for increasing connections between preservation and sustainability. WBDG’s Historic Preservation Subcommittee adds several guidelines that marry LEED guidelines for “greening” existing buildings with processes that incorporate specialization for historical buildings (here). However, there are several things individuals in and building and homeowners can do as well. On a community scale, The National Trust for Historic Preservation includes information on helping preserve your community and designating a historic place. Below are tips for owners of older buildings and homes. These are based primarily on the framework provided by the National Trust for Historic Preservation’s Meghan White in “8 Ways to Green Your Historic House“, listed below, as well as information from other articles and our own expertise:

  1. Conduct an energy audit. Know where energy may be leaking. White states “A popular example is the blower door test. This test involves using a high-powered fan to take the air out of the building, which depressurizes the interior. The difference in air pressure is then measured with an air pressure gauge.” The pressure difference allows outside air to come into the building via openings, which reveals areas you’ll need to seal.  
  2. Don’t replace windows (or doors, or siding, etc.). As we’ve noted several times, a big misconception is that historical windows are to blame for the drafts in homes. White reports “As the National Trust’s Research & Policy Lab (formerly known as the Preservation Green Lab) notes in their study Saving Windows, Saving Money, historic windows rarely deserve to be completely replaced. Instead, weatherstrip them or install minimally invasive storm windows so that they keep the drafts out and lower your energy bills. The study found that retrofitting windows are the most cost-efficient way to decrease a historic house’s carbon footprint. As a bonus, old growth wood found in historic windows lasts longer than modern day wood, so preserving your historic windows will keep you from having to replace them more often.” Similar points can be made for doors, siding, and many exterior home parts that separate the outside from the inside. DAHP adds that more energy is lost from plumbing openings and uninsulated ducts than windows. The key is to repair, restore, and maintain these protections from the outside elements.
  3. Insulate the attic and basement. White notes that energy escapes through uninsulated spots such as basements, crawl spaces, and attics. Insulating them can help to prevent air from escaping. They say “Cellulose is a great option because, unlike spray foam, it’s reversible.” They also caution “You should refrain from insulating walls because you’re removing the permeable vapor barrier inherent in historic structures. The walls of historic houses are made to breathe, but inhibiting movement of air and heat through and around the wall can lead to issues like trapped moisture.” This issue is closely related to our points about differences in modern mortar and historical mortar, and the inherent breathability of old wall materials. 
  4. Take advantage of your house’s natural passive heating and cooling. White says “Artificial cooling and heating methods can be some of the highest energy consumers in a historic house.” They suggest using your historical home’s shutters to cool your house naturally: open your windows and latch the shutters to allow natural air flow. The added bonus is it will shade your interior from the sun. Window awnings that are historically appropriate can also provide similar benefits. In cases where you want or need additional electric components, consider finding a preservation and sustainability-minded HVAC professional who can retrofit systems with little disturbance to your home’s historic fabric, as we discussed here
  5. Consider installing renewable energy sources. Installing solar, wind, or geothermal renewable energy sources on your historic property are also options to consider. White says “Solar panels produce electricity naturally and will help lower your bills. When connected to a utility power grid, modern wind turbines can also help create electricity using renewable resources and in a more cost-efficient manner. Read more about installing solar panels on historic properties here.” Tesla has also developed solar panels that are extremely sympathetic to the historical aesthetics of an older home, though it may be cost-prohibitive for many.
  6. Pay attention to your landscaping. Trees may help to conserve energy in your house,with deciduous trees providing shade in the summer and fallen leaves allowing sunlight to warm your house in late fall and winter. Another issue we acknowledge is environmental damage due to combined sewer systems in many cities. When it rains too much the system becomes overwhelmed and this causes untreated sewage to be dumped into streams and rivers and contaminates waterways. The EPA fines communities every time this happens. As an individual homeowner, you can prevent some of your own contribution to this problem by: creating a rain garden to divert the water away from the storm drain and also away from the foundation; installing permeable pavers laid in the traditional manner (with sand underneath instead of mortar); and you can build a drywell. Check with your local municipality to see if they have a grant to help defray the costs of to property owners who make these changes. 
  7. Change your Lightbulbs. White points out “According to the General Services Administration, High Efficiency Incandescent (HEI) lamps reduce energy by 50 to 75% and use only 25% of the energy that regular incandescent bulbs use. They also don’t alter the appearance of historic light fixtures where the bulbs are visible, like LEDs do. Otherwise, LEDs are a good option when the bulb is obscured by opaque shades or lenses.”
  8. Reuse old materials or salvage. White encourages readers renovating historical buildings to replace missing pieces with materials from salvage companies before resorting to all-new material. This helps preserve historical pieces and prevents some landfill waste. 
     

IN SUMMARY:

Preservation and sustainability have much in common, and destroying or demolishing old buildings is more wasteful than helpful, even when replacing it with a new “green building.” It is best to preserve what we do have, by repairing, restoring, and maintaining these buildings. 

Winter may soon be coming to a close, but there’s still time during the tempestuous month of March for Spring to “come in like a lion,” as the old proverb goes. The uncertainty of weather related to climate change aggravates the issues we already see at the end of Winter as well, adding to the concerns of homeowners attempting to maintain the energy efficiency and temperature of their homes. With that in mind, we’re focusing on energy efficiency for historic buildings for today’s blog post. 


Photo by Alessandro Bianchi on Unsplash

First, let’s debunk a myth about old homes and energy efficiency. A common misconception about older buildings is that they are drafty, inefficient energy hogs. The truth is that the buildings with the worst energy efficiency were built between 1940-1970. Energy was cheap and there wasn’t a big push to conserve our resources during that time-period. Buildings constructed before 1940 were made with energy savings, thermal performance, and physical comfort in mind. By maximizing natural sources of heating, lighting, and ventilation, these buildings were comfortable in all seasons.

Still concerned about energy efficiency in your historic building or home? Read on for advice on improvements that will not sacrifice the historical integrity of your space.
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TIPS TO INCREASE ENERGY EFFICIENCY

ON YOUR OWN:

  • Change your Habits.  Install timers or motion detectors on lights, attach self-closing mechanisms on doors that might otherwise hang open, install fans and raise your thermostat temperature, use LEDs in your lights and turn off “vampire” devices that use electricity in standby mode or that use electricity in standby mode or whenever that are plugged into an outlet.
  • Remove focus from Siding. Remember our previous post on siding on historic homes. Walls themselves are not a significant source of energy loss, so replacing original siding with new synthetic siding really does not cut costs or improve energy efficiency.
  • Caulking or Weather-Stripping. The easiest tip for increasing the energy efficiency of your building is to reduce the air infiltration using caulking and/or weather-stripping. You can do a self-audit of the envelope of your building (roof; walls and wall penetrations including doors, windows; floor, and foundation) to determine if these methods are necessary. If there are places that you feel cold air coming in you can add additional weather-stripping or caulking to the area and seal the crack. In warmer months this will also stop your conditioned air from escaping to the outside.           2 points of caution:
    • Only use the spray foam against masonry penetrations – it will cause any wood it is against to rot
    • Do not make the building too tight – older buildings were built for air to move and if all air movement is stopped it will cause problems with moisture accumulation
  • Combat the Stack Effect. The method above is helpful, but it does not give you the highest return-on-investment for making your home energy efficient because of the Stack Effect. To combat the Stack Effect, insulate at the basement floor (where the air comes in) and at the attic (where the air goes out). It’s also important to determine the R-Value (measure of thermal resistance) for your area to ensure you are most effectively stopping air leaks.  You can find your recommended R-Value here.                                                                                                                                                                Options for insulation:
    • “Green” or environmentally-friendly options (natural materials like cellulose and wool)
    • Fiberglass
    • Spray foam
    • Foam board (purchases can be made at big-box stores or SIPS)

WITH PROFESSIONAL HELP:

  • Seek Professional Assistance. Review our post on hiring the best person for the job. 
  • Have a Maintenance Appraisal Performed.  If you are concerned about identifying air leaks on your own, a maintenance appraisal performed by a qualified contractor will locate any source of air leakage and provide you with a plan-of-attack to remedy the problem without damaging the historic aspects of your home.
  • Schedule an Energy Audit.  Both the maintenance appraisal and an energy audit are absolutely essential things that need to be done BEFORE you implement any energy improvement measures in a situation where you do not have enough knowledge to take care of things yourself.  The energy audit will evaluate your home’s current energy performance and identify any deficiencies in both the envelope of your home and/or mechanical systems.

FURTHER READING:

Window repair, restoration, or replacement is an unavoidable topic of concern in historic buildings. Windows in your historic property are like the eyes of the home. They are an important piece of the historical fabric of the location, and also play an integral part in energy efficiency of the property. Simultaneously, they are one of the most vulnerable and “at-risk” elements of our architectural heritage. Replacement is not always the most cost-effective or energy-efficient answer. Determining the extent of disrepair in your windows is your first step in deciding whether to repair, restore, or replace them. 

Photo of our restoration work on windows at Franklin Street Station in Reading. 

Why are original windows important? They are considered a significant feature of a building, making up both exterior and interior architectural elements and usually 20-to-30 percent of the surface area of the building. The shape and materials, moldings, trim and window pane arrangements are all clues to the age of the building. To further illustrate these unique characteristics, here are examples of window styles and characteristics from the 18th, 19th, and early 20th century. The majority of the features that make original windows special are not replicable in replacement windows; you could replicate them in reproduction windows, but that is not what most people think of when they are discussing replacement windows. These elements include antique (wavy) glass, true divided light sashes, and traditional joinery.

Why are original windows endangered and at-risk? Several preservation organizations, including Maine, Virginia, and New York, have noted in recent years the endangered status of historic original windows. Even we have had first-hand experience talking with well-intentioned homeowners who’ve been convinced by saavy sales people to replace their original windows with modern ones under the guise that they are more cost-effective or energy efficient, only to regret the decision a few years later when the “superior” new windows are no longer functioning properly and are incurring more costs for energy, repair, and replacement. 

Are original windows energy efficient and cost-effective? Energy efficiency is a major concern when it comes to windows. We’ve noted in a previous post on Siding on Historic Homes that heating and cooling energy loss is associated most with windows, doors, and roofs, and this is often worse with modern replacements and materials. Meanwhile, original windows have a proven track record of durability that far exceeds that of new replacement windows, as long as they are properly maintained. In fact, most are 100+ years old. The National Park Service’s Preservation Brief No. 3 and their Testing Energy Performance of Wood Windows in Cold Climates both discuss energy efficiency in greater depth. The latter of the two aforementioned resources points out that replacing historic windows does not necessarily result in greater energy savings than upgrading that same window. If you’re short on time, you may instead choose to read one of our other brief articles on energy-efficiency and cost-effectiveness of original windows. On average, the energy savings after a replacement window is installed is less than $2/year. Restoring and repairing original windows can achieve almost the same energy efficiency, and is more cost-effective in the long-run because new windows will not last as long. 

Now that you understand the significance of original windows and the importance of saving them, how do you know if your original windows are repairable or restorable? First, consider that most materials and methods used to build the original windows are made to be repairable, so there is a higher likelihood that they are salvageable. Replacement pieces can be made rather than replacing the entire unit (consider our woodwork at the formerly abandoned Franklin Street Station in Reading, PA, whose windows were in a shocking state when we first encountered them; alternatively, you can see the results in-person while enjoying craft beer and a bite to eat at Franklin Street Brew Pub now in the station). Things to evaluate to see what repairs windows might need:

  • Loose frames and sash components
  • Slipped sills
  • Poor fitting sash and storm assemblies, and misaligned frames
  • Loose, open, or decayed joints at sash or frame corners
  • Loose hardware, broken sash cords/chains, worn sash pulleys, locking difficulties
  • Deteriorated weather-stripping
  • Broken/cracked glass, loose or missing glazing putty
  • Peeling paint
  • Window well debris accumulation

Some of these issues are easy to see and address. Others, including locking difficulties and window well debris accumulation might signal a misaligned sash and could necessitate the involvement of a skilled person to make those adjustments (or at least consult with you about what to do). All of these repairs will increase the energy-efficiency of your windows.

What do I do if a previous owner already replaced the original windows and updated replacement is necessary? There are several options to choose from:

  • Rebuild with antique glass
  • Rebuild with true divided lite and insulated glass
  • Replacement with modern replacement windows – The National Park Service’s Preservation Brief No. 9 has a list of what to look for in replacement windows, as well as ideas of where to find historically sensitive replacement windows

For more information and resources:

  • Visit our window post archives link
  • We typically recommend 2 Canadian manufacturers for modern replacement windows: Norwood Windows or Loewen
Historical buildings were built when neither advancements in technology nor construction technology was in abundant supply.  Early designers made the most of building materials and design options to construct buildings with a powerful combination of harnessed natural resources and innovative design that worked together to maximize energy efficiency.

Everything from exterior paint colors, locations of balconies, numbers and placement of windows, to physical placement of buildings on lots was carefully considered to maximize heating, lighting, and ventilation in traditional construction.

The results are astounding, and studies have shown that properly restored and maintained 18th-, 19th, and early 20th century buildings can be just as energy efficient as new construction, and in many cases even more efficient.

The historical wood windows in your building contribute to that energy efficiency, and, contrary to urban legends, new replacement windows are not more energy efficient than historical wood windows.  Typically, studies that conclude such a finding have compared new replacement windows with historical windows that have not been maintained or restored, are decaying, and have no complementary energy retrofits, such as weather-stripping and storm windows.

Studies on energy efficiency also usually fail to consider “embodied energy”. Embodied energy represents the energy it took to manufacture a product.  They say the greenest building is the one already built.  This is true when you consider the embodied energy – an existing energy investment that will never be able to be recaptured once you destroy the product it’s embodied in.

Historical wood windows have an embodied energy value that includes all the energy from harvesting and milling the wood to transporting and manufacturing the windows to installing them in your historical building.  Preserving existing windows conserves that embodied energy and eliminates the need of additional energy to manufacture replacement windows.  When you take all energy into consideration for defining the energy efficiency of windows, historical wood windows are far more energy efficient than replacement windows.

Tips For Improving Energy Efficiency

Here are some tips for improving the energy efficiency in your historic home.

  1. Have a maintenance appraisal performed.  When not properly maintained, there are many ways a historic home’s energy efficiency suffers – such as air leaks into and out of the home.  A maintenance appraisal performed by a qualified contractor will locate any source of air leakage and provide you with a plan-of-attack to remedy the problem without damaging the historic aspects of your home.
  2. Schedule an energy audit.  This could really be tied for the #1 spot; both the maintenance appraisal and an energy audit are absolutely essential things that need to be done BEFORE you implement any energy improvement measures.  The energy audit will evaulate your home’s current energy performance and identify any deficiencies in both the envelope of your home and/or mechanical systems.
  3. Implement these findings.  Hire a qualified contractor to eliminate any air infilitration, repair windows and perform the other maintenance affecting your home’s energy efficiency.  Hire a qualified energy contractor to replace any mechancial systems found to be deterimental to your home’s energy efficiecny.  Make sure both of these contractors have a proven track record of working with historic buildings in a way that does not damage the architecture and its features.
  4. Change your habits.  Install timeers or motion detectors on lights, attach self-closing mechanisms on doors that might otherwise hang open, install fans and raise your thermostat temperature, use LEDs in your lights and turn off “vampire” devices that use electricity in standby mode or that use electricity in standby mode or whenever that are plugged into an outlet.
  5. Install insulation. Ther is a lot of misinformation regarding the best ways to insulate your house, and some of them can even damage your home.  Have the historic contractor and energy consultant you hire work together to devise an insulation plan specifcially tailored to your home, so you won’t compromise its architectural integrity.
Historic Wood Window Restoration, Save Historic Wood Windows, Wood Windows vs. Replacement WindowsWood windows are an integral part of the innate energy efficiency of historical buildings. If we have learned anything from history it is that sometimes with all our modern advancements we do ourselves more harm than good.

Advancements in technology do not always produce better results, and construction technology isn’t exempt from that. Built in a time of readily available building materials and energy sources, modern building designs typically make poor use of both. Historical buildings were built when neither was in abundant supply and early designers made the most of building materials and design options to construct buildings with a powerful combination of harnessed natural resources and innovative design that worked together to maximize energy efficiency.

Everything from exterior paint colors, to locations of balconies, to numbers and placement of windows, to physical placement of buildings on lots was carefully considered to maximize heating, lighting, and ventilation in traditional construction.

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The results are astounding and studies have shown that properly restored and maintained 18th & 19th Century buildings can be just as energy efficient as new construction, and in many cases even more energy efficient. (Perhaps not surprisingly, studies have also shown that buildings built in the 1950’s through the 1970’s were the biggest energy consumers of all.)

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The historical wood windows in your building contribute to that energy efficiency and, contrary to urban legend, new replacement windows are not more energy efficient than historical wood windows. Typically, studies that conclude such a finding have compared new replacement windows with historical windows that

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have not been maintained or restored, are decaying, and have no complementary energy retrofits such as weather-stripping and storm windows.

If you would like to read these studies, you can access them in the resources section of our website.

Studies on energy efficiency also usually fail to consider “embodied energy”. Embodied energy represents the energy it took to manufacture a product. They say the greenest building is the one
already built when you consider this embodied energy – an existing energy investment that will never be able to be recaptured once you destroy the product it’s embodied in.

If the greenest building is the one already built, then the greenest window is the one already there. Historical wood windows have an embodied energy value that includes all the energy from harvesting and milling the wood to transporting and manufacturing the windows to installing them in your historical building.  Preserving existing windows conserves that embodied energy and reduces the use of additional energy when making replacement windows.

Which means that when you take all energy, energy expended on heating and cooling costs as well as the embodied energy, into consideration for defining the energy efficiency of windows – historical wood windows are far more energy efficient than replacement windows
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