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Historic Preservation: the
Ultimate in Green Building
(The following is adopted from Scott Butcher’s
presentation of the same title, recently delivered as keynote of Historic
York, Inc.’s annual meeting and at several Rotary Clubs.)
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
(www.wbdg.org), really
sums it up:
“Sustainability begins with preservation.”
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 conditioning, 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 buildings, 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.
Building owners 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 building 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!) To put that figure into
perspective, think about 640,000 gallons of gasoline – the equivalent of 80
billion BTUs. At $2.00 per gallon, that’s $1.28 million worth of gasoline,
which is no small figure at today’s gasoline costs.
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.
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