The effort by the building industry to decarbonize the built environment has been underway for twenty years now. New York City, of all places, has made a commitment to reducing the carbon footprint of its existing structures, including its largest skyscrapers. Many of these examples were demonstrated at an APA Conference in the spring of 2001, called "Green Towers".
In 2009, a $20 million eco-refit of the Empire State Building as an addition to its $500 million renovation was announced, and in 2011 that retrofit was completed. Tony Malkin leads a discussion of the project which involves a 3 year payback on operations and maintenance. And that doesn't include a an accounting of the savings in "embodied energy" of the existing iconic structure and keeping massive amounts of demolished material out of landfills.
Existing buildings are full of energy efficiency opportunities waiting to be realized. While some savings are obvious and easy to reach via one-off upgrades of windows, lighting and appliances, by using an integrated, whole-buildings design approach, profoundly larger energy savings can often be gained at little or no added capital cost. The efficiencies of many systems work together to create a drastic reduction in energy and water use.
The specifics of a deep retrofit are described here, as one of the initiatives established by the Rocky Mountain Institute. There's many tools on this site that help determine the best approaches to different recycling and retrofit issues with these older structures. It involves a whole process beginning with selecting the goals and going all the way through to measurement and verification of the resulting improved structure, thus completing a cycle of design and management.
In greater detail, the RMI has actually made available a complete white paper that discusses creative elements of deep whole building retrofits, published by ASHRAE. It's called "Whole-Building Retrofits: A Gateway to Climate Stabilization", by Victor Olgyay and Cherlyn Seruto. Olgyay is the author of the classic book, "Design With Climate" published in 1963. This approach has been evolving for decades, and the integration of natural principles, technological advancements and digital building managment has opened the door to an era of sustainable practices with the existing infrastructure of historic buildings. You couldn't build many of them today - the structures are the result of the kind of construction labor and material resources that you can't find today, hence the greater value in preserving and improving structures like this.
It's not just an old building anymore, it's a symbol of the new approach to the urban environment, that values what has gone before and conserves the heritage, the embodied energy and keeps that carbon out of the natural environment.