Does Saving Historic Buildings Really Save Energy?
The preservationist wisdom is that a lot of energy--gallons and gallons of gasoline--is locked up in our historic buildings, and should be saved. It's time to update that wisdom.
A surreal magazine ad just got even more surreal for me.
After learning of the fire at the historic 1871 Brooks House here in Brattleboro, Vermont last week, I quickly got to wondering, will the owner be put in the painful position of choosing to salvage a beloved historic property, or to build new? Similar choices are faced with sad frequency in historic downtowns across America.
A second look at a surreal magazine ad
The question brought to my mind an iconic poster from the 1980. The ad depicts a "jerry can" style gasoline can--red, rectangular, with a metal nozzle coming out the top.
The surreal thing about this poster was that the gasoline can was drawn in the shape of an archetypal three-story, brick "Main Street" building, with a storefront below and offices and apartments above. The tall rectangular building becomes a tall gas can, with the red brick looking like the red metal can. The fuel nozzle sticks out of the roof.
Believe it or not, this poster was run by the National Trust for Historic Preservation. It remains a touchstone today in preservation and green building circles. After seeing one of our iconic downtown brick buildings go up in flames, I had to ask myself, why would any responsible organization ever want to equate an aging building with an explosive, flammable fuel?
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Saving buildings saves their "embodied energy"--or does it?
The answer is in the form of an argument often made in preservation circles that we should save historic buildings because of their "embodied energy." The idea is that it takes a lot of energy to build a building. Firing bricks, sawing wood, making windows and doors and door hardware, trucking those materials in, and getting all the workers to the jobsite every day--all the ingredients in a building, and every step in putting those ingredients together, takes energy. That's energy that we have to get from somewhere, most often burning coal, oil, or other irreplaceable fuels.
When a structure is completed, you have not only that building, but you also have a pile of energy in the shape of a building. That was the simple idea expressed by the National Trust in its magazine ad. The text with the ad read, "It takes energy to construct a new building. It saves energy to preserve an old one."
The National Trust was arguing that saving old buildings isn't just good for the historic fabric of our communities--it also preserves the energy value of the materials involved. I've heard preservationists go so far as to talk about how many gallons of gasoline are represented in each square foot of a historic building.
I think it's time for a new metaphor, and not just because of the fire.
Energy spent in construction is water under the bridge
We should save historic buildings because they are beautiful and because they are important to the fabric of our communities. Relative to the environment, they are often located in central, downtown locations that are pedestrian and mass-transit-friendly. While they aren't usually super-efficient, they are more energy-efficient than you might think. According to the quadrennial study of buildings in the U.S. by the Department of Energy (CBECS), buildings built before 1960 use less energy per square foot, on average, than buildings built since then.
However, when it comes to the energy expended in the 19th century to build that structure, that's not a good reason for saving a building from demolition--it's water under the bridge. Energy spent 2, 20, or 200 years ago to build a building simply isn't a resource to us today.
The real question: Does reuse conserve energy today?
On the other hand, energy that we might use today or in the next 100 years is a resource that we need to conserve. A better way to look at the issue is whether reusing buildings can save us energy compared with demolishing and building new.
Given a choice between reusing and starting fresh, which process will use more energy in construction? Once a building is operating, which building will use less energy to operate--the reused building, or the new one? How do the financial costs compare? If energy is saved, but at great cost, is it really worth it? These are questions any owner should ask if faced with that decision.
Let's take a scenario where it costs us extra energy to build new, but saves us energy in terms of operation. How many years before the energy we save during operations makes up for the extra energy spent during construction? If that point is decades down the road, then perhaps we'd be better off reusing the historic building and putting our energy elsewhere today. Only by really thinking through these questions can we decide if saving a historic building really saves us energy.
The National Trust updates its data
These analyses can get complex and emotionally laden, so it's fortunate that the National Trust is working to update its story using life-cycle assessment (LCA) methods that look at costs and benefits from numerous angles. The study, begun last year and expected to net results soon, should give us a good idea whether reuse makes sense, in several different typical scenarios.
I'm hopeful that the study may help bridge a gap between the historic preservation and green building communities, who have sometimes clashed over the fate of existing buildings. Although plenty of middle ground has been staked out over the years, environmentalists have tended to focus on energy efficiency even at some cost to historic fabric, while preservationists insist that the "greenest building is the one that's already built." Both sides have a point, but each needs to learn from the other.
Some other "embodied" concepts that are more useful
The "embodied energy" concept isn't dead, by the way. In fact, it has grown and been expressed in more and more flavors over the years. In the 1970s we had an "energy crisis"--today we also have a "climate crisis," so accordingly, people are talking about the "embodied carbon" in everything from our building materials to our bike frames. Water quality and water shortages are also worldwide issues, so some people are looking at the "embodied water," a.k.a. "virtual water" of those Egyptian cotton sheets, or the morning cup of coffee. (That's 2,600 gallons per sheet, and 37 gallons per cup, respectively, according to some calculations.)
These measures could be much more useful than "embodied energy" ever was. That's because "embodied water" relates to agricultural and manufacturing processes for consumer goods being made and used today. Focusing on reducing that use, and making our goods more durable, would have immediate environmental and economic benefit.
Another exciting development is the 2030 Challenge for Products, which was launched in February of this year. Recognizing the immediacy of the climate crisis and the large amounts of carbon emitted to make our building materials, the challenge calls for a 50% reduction in the embodied carbon of products by 2030. Because we don't yet have reliable carbon numbers for building products, the immediate question is, "50% reduction from what?" Establishing baselines for different product categories will be a project taking several years, but I'm excited to see the results.
Maybe we'll even see an ad campaign that makes these abstract concepts more concrete. My advice: put down the gas can!
(2011, April 26). Does Saving Historic Buildings Really Save Energy?. Retrieved from https://www.buildinggreen.com/blog/does-saving-historic-buildings-really-save-energy
I am president of the Architectural Conservancy of Ontario and hope nobody in Canada reads this, but I actually agree with you about the embodied energy argument, it is a sunk cost. And you are also correct in your critical point that "they are often located in central, downtown locations that are pedestrian and mass-transit-friendly. While they aren't usually super-efficient, they are more energy-efficient than you might think."- BuildingGreen has been at the forefront of the argument that transportation energy efficiency is an important factor. A Main Street retail building with residents above is probably the most energy efficient built form that there is from a transportation point of view.
But one also has to note that they are not only relics from the past, but templates for the future. They had to operate before air conditioning was invented, before electric light was affordable and power sources dependable, when heat meant shovelling coal by hand. So they used it frugally and ventilated naturally and were lighted through big windows.
Every time we tear an old building down and replace it with a modern high tech building, we are trading buildings that can operate in a pinch without a lot of external support for one that cannot get through a couple of hours without it. They are resilient. They are adaptable. They are usually pretty healthy; formaldehyde and vinyl and brominated fire retardants were not usually in the specs.
In an era of peak oil and diminishing resources, resilience matters.
I'm looking forward to the National Trust study. Two years ago we built our new architectural offices on a hilly downtown site in a small town containing an iconic 1860's historic house, which we had to structurally reinforce and move to a new foundation. Not only did we honor the embodied energy in the building and keep numerous tons of materials from going to landfill or being recycled, but we honored and preserved the prominent history of this well-loved building and landmark for the town, maintaining the town's historic fabric and diversity, i.e. link to the past and an example of historic building methods and materials, and "upgrading" it for adaptive reuse, which will hopefully make it viable for the next 100 years. For all of these reasons I believe that historic preservation and sustainability go hand in hand.
One more factor to add in the evaluation is the effect of a facility location on its community. Many times demolishing and building back in place is not an option - building owners may opt to relocate to sites away from urban centers. Staying put and renovating the existing building can only add value to adjacent properties, thereby encouraging others to stay, possibly invest in their properties (and increase tax revenues to support infrastructure), and reduce sprawl. This is especially true with neighborhood schools or other significant public structures.
When you're talking about the extra energy involved in construction of a new, more energy-efficient building to replace an historic one, don't forget to count all the energy involved in demolishing the old one and disposing of the materials; remembering that it takes time and effort to sort out precious (and now rare) tropical hardwoods and ornamental stone carefully enough to maintain its resale value, and that burning waste timber releases CO2 to the atmosphere.
If you're thinking of a downtown replacement project, don't forget all the energy that's going to be wasted by automobiles and trucks stuck in traffic jams around the construction site and all the effort you're going to have to make to avoid pollution during demolition.
Is it any wonder that demolition of the Empire State Building wasn't an option; so that after some careful thought and investigation, refurbishment is going to provide energy performance up there with the best of modern building, with far less embodied energy and at an investment with a much shorter payback period than a replacement building.
With credit due to Larry Strain's arguments on this matter, an important factor to consider is that the time frame we have to radically reduce carbon emissions in in years not decades. Co2e emitted to construct a building is emitted now as opposed to 20 or 50 years from now, in the case of operational energy. I am coming around to valuing embodied carbon more than I have in the past.
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