Historic Preservation: The Ultimate in Green Building, Part II
Recently, while conducting research for a presentation, I came across a simple yet profound statement:
“The greenest building in the world is the one that is already built.”
I had the “V8” reaction as in, “Wow, I should have known that.” But the sad truth is that most people don’t think of historic buildings as being green. The U.S. Green Building Council, in fact, does not penalize a project for tearing down an existing building (think of all the waste, much less the energy used to construct that older building that is now being demolished).
Yet another green building reference source, the Whole Building Design Guide, really sums it up:
“Sustainability begins with preservation.”
Take the example from the earlier post – the “greenest building in the world” isn’t nearly as green when you factor in the energy used for the staff to commute to and from work every day.
But how can old buildings be green? They are drafty, and the heating bills are outrageous.
As it turns out, that is a myth.
The U.S. General Services Administration, owner/manager of non-military Federal buildings, conducted a study and found that utility costs for historic Federal buildings were actually 27% less than the utility costs for modern buildings. And another study confirmed that. Buildings constructed prior to 1920 were found to be, on average, more energy-efficient than any building constructed between 1920 and 2000. It has only been in the new millennium that the emphasis on energy efficiency and green buildings has gotten us back to where we were 100 years ago.
So what’s the deal?
Historically, buildings were “green.” With no air condition, primitive insulation, no or early electricity, building designers and constructors had to think about the natural environment. Buildings were sited to take maximum use of the sun or shade (heating and daylighting) and wind (ventilating). Local materials were of course used in their construction, and exotic, water-guzzling plants were unheard of; indigenous plantings were the norm. Light (or dark) exterior colors could reflect or retain heat. Cisterns recycled water and even added a cooling element. Tall windows allowed daylight to penetrate deeply into interior spaces. Shutters actually opened and closed (do yours?). Buildings in the north tended to have thick walls (great insulation) and smaller windows (less heat loss) while buildings in the south used high ceilings (better ventilation) and louvered shutters (keep out the heat from the sun).
The whole green building movement really is a throwback to the past, though using many modern technologies in the process.
When most of us think of older homes, we think of windows. Old windows let out the heat and let in the cold, right? That is another myth.
Only 10% - 12% of a building’s energy loss is through the windows themselves. Most of the heat loss comes from un-insulated attics or walls, as well as window sills that are cracked. Joe Homeowner can install interior (or exterior) storm windows, then caulk and weatherstrip. This can result in roughly the same energy savings as installing replacement windows. And those replacement windows, well, they are pretty bad for the environment. A study in Indiana found that the environmental “cost” of installing replacement windows has about a 400 year payback for energy savings.
This is a “big picture” statistic, however. If you have an old home and install replacement windows, you may notice an immediate savings on your energy bills. In a few years, this savings may pay for the cost for purchase and installation of the windows. (Though you would get the same effect and have a quicker payback with storm windows, caulking, and weather stripping.) But the green movement takes into account more than that. There is an energy cost associated with manufacturing the windows, and transporting them from the factory to the wholesaler to the retailer to you. And replacement windows themselves aren’t very friendly to the environment. They don’t last as long as historic windows, and many of their parts cannot be recycled.
The “Green Preservation” movement is concerned with something known as “Embodied Energy.” Basically, look at any building standing today: there was a lot of energy used to construct it. Energy to create the building materials, transport those materials, and physically construct the building, plus the use of equipment (bulldozers, cranes) and automobiles to transport workers to and from a site. That is a lot of energy – energy that is “embodied” in the building.
Now tear that building down.
All the embodied energy is lost.
A recent study looked at a “typical” 50,000 sq. ft. commercial building in a city. The embodied energy is approximately 80 billion BTUs. (British Thermal Units … 80 billion of them … a lot of energy!) If you are like me, a BTU is an abstract concept. But now think about 640,000 gallons of gasoline, which is the equivalent of 80 billion BTUs. That puts it in perspective. (And at $3.20 per gallon, that’s over $2 million worth of gasoline.)
York has a lot of old, historic buildings. It is part of our charm. In fact, over 10,000 buildings in York County are listed on the National Register of Historic Places, either individually or as part of a historic district (the latter applies to most of York County’s National Register-listed buildings).
Preservation is important for many reasons. It allows us to retain our past. It creates the fabric of our community. And, as it turns out, it helps our environment in ways we never previously imagined.
If historic buildings are green, and York has a lot of historic buildings, then York must be a really green town!
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