“The greenest building is the one that is already built.” Architect Carl Elefante who is the Director of Sustainable Design at Qunin Evans Architects in Washington, D.C. said it very succinctly.
Eco-nerds talk about sustainability and energy-efficient design as much as us preservation-nerds talk about wood windows and plaster. But isn’t it amazing when two worlds that have little to do with each other normally can come together and fight side by side on an issue?
Historic preservation is just that issue. Why you might ask? Because even our drafty, energy-inefficient old buildings from decades past are more “green” than the most energy-efficient LEED Titanium (if there were such a thing) building we could build today.
How is that possible?!
Why Preservation is The Greener Choice
Without a doubt, we can build structures today that are extraordinarily energy-efficient. Once built they recycle water, have living green roofs that keep temps moderate indoors, are net-zero (require no power from the electrical grid). We can build things today that require almost no carbon footprint to operate on an annual basis.
BUT…as efficient as these buildings are, they still need raw materials (wood, metal, gypsum, paint, glass, etc.) in order to build them. And those raw materials need to be processed, shipped, packaged, delivered on site and assembled. That all requires lots of resources and energy.
That is precisely why preserving and repurposing old buildings is a more sustainable option. Old buildings required the same huge list of resources and energy to assemble them 100 years ago, but the work has already been done. The materials are already in place.
If you tear down that old factory to make way for a new super efficient office building, not only do you add hundreds of thousands of tons of debris to the landfill but you essentially throw away all that embodied energy.
What is Embodied Energy?
Old buildings are not just full of history and character. They are filled with the embodied energy from when they were constructed in the first place. What is embodied energy exactly?
Embodied energy is the total energy required for the extraction, processing, manufacture and delivery of building materials to the building site.
It requires energy to:
- Demolish the existing structure
- Haul away the waste from the original building
- Extract raw materials
- Manufacture construction-ready building materials
- Transport building materials to a construction site
- Assemble the physical structure
A building’s worth should not be judged according to the affordability of its power bill.
According to a extensive study by the National Trust for Historic Preservation the following stats were found:
- An existing 50,000 square foot building, represents 80 million BTUs of embodied energy (the equivalent of 640,000 gallons of gasoline)
- Demolition of such a building would result in 4,000 tons of waste
- If only 40% of materials are retained, it would take 65 years for a new green, energy-efficient building to recover the embodied energy lost.
Many new buildings have a life cycle of far less than 65 years today. That doesn’t mean these new buildings aren’t green. It just means this simple fact:
Demolishing a historic building to make way for a new energy-efficient building essentially eliminates any energy savings.
So, does that mean we are stuck with inefficient old buildings? Hardly. The tools and techniques exist today to restore and greatly improve the efficiency of our old buildings.
From simple techniques like weatherstripping and storm windows to more involved deep-energy retrofits our old stock of historic homes and commercial buildings can be made nearly as efficient as today’s greenest buildings with much less waste and effort than new construction.
There are ideas like:
- Repurposing old warehouses into urban lofts
- Turning shuttered factories into schools
- Converting old retail spaces into character rich restaurants
Not only do we preserve the embodied energy that these buildings have held for centuries, but we preserve important pieces of our rich history.
So, the next time your town is making plans to demolish an old structure to make way for something new, remind them that there is a better way. Speak up before the wrecking ball makes its appearance or you may wish you had.