The Definition of Embodied Energy

Posted by on Apr 16, 2013 in Austin, Journal, Material Conservation, Sustainability
The demolition of the William Travis Building, May 26, 2011, Austin, Texas

The demolition of the William Travis Building
on Guadalupe, May 26, 2011, Austin, Texas

Over the next 20 years, Americans will demolish over 1/3 of our building stock (approximately 82 billion square feet) in order to replace seemingly inefficient buildings with energy efficient, sustainable “green buildings.”[i]  However, existing buildings have several inherent benefits that make them worthy of reuse.  Creative design, state-of-the-art building systems, and modern uses are not only possible but highly desirable within existing and historic buildings.

  • Materials: older buildings (Pre WWII) are generally constructed with indigenous and higher quality materials that have aged well compared to their modern counterparts.
    • Lumber for buildings constructed in Austin came from old growth forests in the Bastrop area.  The ring density and resistance to rot makes this lumber superior to commercially available materials today.
    • Masonry comes from the Texas Hill Country or local brick kilns, and has a multi-generation life span.
    • Older roof systems are often of higher quality than new roofs, made of materials like copper, slate, clay tile, and standing seam metal that can be repaired rather than replaced, and have life spans that are 3-5x that of composition shingles or membrane roofs.
  • Design: Buildings constructed before the common use of air conditioning are designed to promote air circulation and lower temperatures in the heat of the Austin summer.  They use design features such as operable windows, porches, sloped roofs, and natural shading to repel the summer heat and absorb the winter sun for natural climate control.  For example, window shutters (or blinds, as they were called historically) were not ornamental.  They were closed in the heat of a summer day, with the slats adjusted to provide shade with open ventilation.  In winter months, the blinds were left open, flush to the sides of the house, to allow the sun to warm the house through the windows.

Renovation and adaptive reuse of existing buildings achieves the sustainability movement’s “triple bottom line” of economic, social, and ecological balance.  Buildings are one of our county’s most significant manufactured products, or as Jean Caroon, principal architect at Goody Clancy of Boston says, buildings are huge hand-made objects.  They are a composite of millions and millions of things.  Everything, each piece of our world that is a manufactured piece or a moved piece or a cut piece of stone, has tremendous environmental impacts along the way.”  This concept is known as “embodied energy”.

Memorial erected in 2012 following the demolition of the William B. Travis Building.   The site remains vacant today.  Photo taken November 17, 2014.

Memorial erected in 2012 following the demolition of the William B. Travis Building. The site remains vacant today. Photo taken November 17, 2014.

“Embodied energy calculates what is the total cost of the components incorporated into a building starting with what’s the energy expenditure in getting that rock or that oil or that material out of the ground.  What is the energy incorporated in processing that raw material into a building material? What does it cost to move that building material from point A to where the building is being constructed? And then, what is the energy that’s consumed in both human and material form to incorporate that building component into the building?” – Donovan Rypkema, The Greenest Building

The energy used to construct a building is 30-50 times the amount needed to operate the building on an annual basis.  Consequently, it takes an average of 40 years for an energy efficient new home to recover the carbon expended in the construction of the home.[ii]  Factor in to that the cost, in both financial and environmental terms, of demolition and replacement, and it makes sense to conserve and maintain existing buildings wherever possible.  Conservation of existing building materials protects natural resources, reduces transportation costs for new materials, and reduces impacts on our local landfill.

It is our challenge and our passion to revive existing buildings for everyone to enjoy.

[i] The Greenest Building transcript, Jane Turville, 2011.

[ii] New Tricks with Old Bricks, Empty Homes Agency, UK, March 2008