Inherent Sustainability of Old Buildings
In recent years preservation has been recognized as a “recycling program of historic proportions.” And when you stop to consider, it is actually a good description. Saving old buildings helps retain history, identity, beauty, and connections to our past, but in terms of sustainability saving old buildings excels at recycling and reusing embodied energy. Many buildings more than 50 years old have thick walls that take advantage of thermal mass, reducing the amount of energy needed to heat and cool. They also have high ceilings, transom windows, and larger operable windows to bring in natural light and help ventilate the building. Large shaded porches, heavily tree lined streets, and shutters help control solar heat gain. These, among many other elements of architecture that have been overlooked since the invention of electricity and the HVAC system, are inherently sustainable features. These creative methods employed in early architecture are energy efficient because they use no energy when operating. When properly managed, these inherently sustainable features can outperform any modern green building.
Inherently sustainable features are characteristics of a building or site that, through their design, physical materials or building or natural systems, embody principles of sustainability.
-Building Resilience
Building Resilience is a website dedicated to sustainable rehabilitation of existing buildings in Canada. Along with standards and guidelines for conservation and case studies, the site includes three pages worth of inherently sustainable features. These features are notable because of their avoided impact on the environment. They include embodied energy and carbon, traditional building design and construction techniques, use of local, durable materials, the location of the buildings themselves, and their longer life span.
Embodied Energy and Carbon
Existing buildings have an advantage over all new green buildings; they are already standing and have been for decades which mean they have a wealth of embodied energy. Embodied energy is the total expenditure of energy involved in the creation of the building and its materials. Embodied carbon is the carbon emitted during construction including process required to extract, fabricate, transport, and assemble the material. It takes 15 to 40 times the amount of energy to build a building than it does to operate it in one year. Making the case for keeping a building standing rather than demolishing and replacing it.
The functional adaptability of historic buildings is one of their great under-recognized attributes. You cannot have sustainable development without a major role of historic preservation, period.
-Donovan Rypkema
Design and Construction
Older buildings when constructed used traditional design and construction techniques that are inherently sustainable. Some architectural styles like the Italianate or Greek Revival employed the use of cupolas. While serving an aesthetic purpose, it also helps to vent the building and sometimes provide access to natural daylight. Nearly all architectural styles since the revolution incorporated porches, especially in southern states. Porches were important elements to provide shade for the building occupants, but also reduced heating loads on the building. Another tool used to reduce heat loads were projecting eaves or roof overhangs, a character defining feature of craftsman style buildings. Awnings, a common sight on commercial buildings before the invention of air conditioning, were used to reduce sun exposure, glare, and solar gains. Today shutters are a fixed addition to buildings, serving as a decoration instead of their original purpose which was to either block out sunlight during the warmest part of the day or to protect against storms.
Buildings designed with interior courtyards allow for more access to natural light on the interior and greater passive ventilation through window openings. These courtyard spaces when embellished with fountains help to cool the space significantly, providing reduced heating loads on the adjacent walls.
On the interior, high ceilings allowed air flow and improved natural light when tall windows were used. Today, high ceilings make it easier to cool the space and encourage airflow when vents are added near the ceiling. Tall windows allow access to natural light that reduces daytime electrical demand. An additional benefit of natural sunlight is a dynamic and pleasant space and improved productivity by the building occupants. The transom window, a feature that has been covered up, removed, and on a rare occasion restored in old buildings, was an element designed to allow adaptation to changing conditions when operable or to allow light deep into narrow commercial spaces.
Materials
Buildings constructed prior to the 20th century used materials from local quarries or a local brick kiln was constructed using material found nearby to produce the brick. This greatly reduced the amount of energy that went into construction by negating much of the CO2 emitted during the transportation of materials to the site. The railroad had a profound impact on these practices, making it easy and affordable to ship building material all across the U.S. starting in about the 1860’s. Today we ship materials across oceans and then send it by truck hundreds of additional miles to the job site, burning fuel the entire way.
Materials used in buildings before the mid-20th century were generally stronger, durable, and retained their value over time. A great example is wood windows. Many residents of old buildings with original wood windows complain of their draftiness and want them replaced. But these windows were made with old growth wood that has withstood the elements for 100 years in most of these homes. They do not need to be replaced with vinyl windows that cannot be repaired and will fail in 30 years or less. Instead, a good repair done by an experienced tradesman can restore the windows to another 100 years of life. When combined with a storm window the time frame is extended even further before repair is necessary. This saves debris from the landfill, the embodied energy of the windows, and the cost of replacement 30 years down the road when the replacement window needs to be replaced.
Buildings which used materials like stone, concrete or brick, have the advantage of thermal mass or the ability to store and release heat throughout the day. The walls take in a lot of heat during the day and then gradually release it at night. This provides inertia against temperature fluctuations to help stabilize the interior temperature. It’s easy to tell the difference when you are standing in a solid brick building compared to a framed bungalow. My office, located in the front of my 1920’s wood frame bungalow with six inch wood walls gets quite warm in the late afternoon. The masonry building where I work doesn’t have this same problem.
Life Span
The life span of a building construction before 1950 is far greater than more recent construction. According to a speaker during a Getty Center colloquium, the average life span of masonry or wood buildings is 120 years, compared to just 60 years for a reinforced concrete or glass curtain wall structure. Many big box stores and shopping malls built 30-40 years ago are already being torn down showing an even shorter lifespan. Our oldest buildings were constructed with durable materials—brick, stone, and stucco. Look at any intact commercial district and you will find stone and brick. These structures have an ability to stand for thousands of years if property maintained with cleaning, re-pointing, and plaster repair. The proof is in many ancient structures such as the 2,000 year old Pantheon in Rome. If built using today’s materials of asbestos, vinyl, or fiber cement the Pantheon would have been rubble long ago.
Location
Older buildings are built with walkability in mind. Districts predating 1920 assumed most users were traveling either by foot or wagon and therefore were built closer together. This doesn’t necessarily mean dense urban areas. Many small rural communities have houses built on smaller lots close to the downtown. In larger communities, construction of higher density row homes not only took advantage of expensive lots, but also conserved energy by limiting the number of exterior walls exposed to the elements. Another inherently sustainable feature of larger cities is the access to transit or the proximity of destinations within walking or bicycling distance. This reduces the need for single occupancy vehicles and therefore reduces traffic congestion, fuel emissions, and parking demand.
Conclusion
As communities consider demolition permits and new sprawling suburban developments, they should first consider preservation. The greatest contributor to greenhouse gas emissions is our building stock. The idea that we should build more new green buildings to fix the problem is actually just making the situation worse. The Intergovernmental Panel on Climate Change (IPCC) stated “…over the whole building stock, the largest portion of carbon savings by 2030 is retrofitting existing buildings and replacing energy using equipment…” It makes sense, when you consider all the ways mentioned above that an existing building is inherently sustainable. We can modify systems to take advantage of these features and improve their function with modern technology. Historic preservation can and should become a crucial contributor to the principles of sustainable development since it is after all a recycling program of historic proportions.
