Historic preservation and sustainable design are two disciplines that no longer need to be at odds but can actually join together to improve the sustainability of buildings, argued Maria Casarella, an architect with Cunningham | Quill Architects, Brendan Owens, Vice President of LEED Technical Development, and Eleni Reed, chief greening officer at the U.S. General Services Administration (GSA). These experts explored all angles of the raging "historic preservation vs. sustainable design" debate during a lecture at the National Building Museum (NBM).

How Historic Preservation and Sustainable Design Overlap

Given all the embodied energy found in old buildings filled with bricks, metal, concrete and other materials, why pull them down in favor of possibly more energy-efficient buildings made of all new materials? Martin Moeller, Senior Vice President at NBM, argued that both old and new LEED certified buildings are "good things" but it's a matter of "juggling." What's the balance, prioritization? Still, for some preservationists, the main issue with the new green building movement, which still only accounts for less than one percent of all buildings, is that existing buildings may be the greenest.

Maria Casarella, an architect who brings sustainable design approaches to many historic preservation projects in the Washington, D.C. area, and who is also on the D.C. Historic Preservation Review Board, said the district, with its wealth of historic buildings, has made great progress on sustainability but the historic preservation community was engaged "late in the game." She said historic preservation vs. sustainable design is a bit of a "false choice," but LEED still fails to account for a building's historic or cultural value. "How do you assign historic value through a points system?"

Eleni Reed at the GSA agreed and said the U.S. government, which is one of the world's biggest landlords, is working on "reinvesting in its existing inventory." Using recovery funds, the Public Buildings Service is transforming many older buildings into "high performing buildings." To date, some 100 historic buildings have been "touched on." Reed believes "sustainability and preservation must go hand in hand."

At the U.S. Green Building Council (USGBC), creator of the LEED rating system, the issue can be broken down into the overall carbon footprint of new green buildings vs. greener building operations and maintenance for older and even historic buildings. Brendan Owens at USGBC said their goal is to create "dashboards" for all buildings so that even historic buildings can track their "operational performance." Owens said "existing buildings still have to operate at their potential."

Some Older Buildings Are Greener

Owens said energy ordinances are "popping up everywhere", which means building managers must disclose how much energy a building is using. Through these programs, the building design and engineering community is discovering that buildings created 80-100 years ago "tend to outperform newer buildings." Unfortunately, he added, many commercial real estate developers don't know this. Owens added that "technically sophisticated buildings may be energy hogs" in comparison with older buildings. He just wants to make sure those older, well-performing buildings are actually tracking their performance. Reed at GSA agreed, saying that the benefits of older buildings "need to be quantified."

According to Moeller, the problem buildings are the ones created 40-50 years ago. These are the worst from an energy point of view. The "1930?s is a significant cut-off point" said Owens. 

To address the issues in these challenging mid-20th century buildings, Casarella thought that a careful approach was needed. "It's not one size fits all." Architects and engineers need to look at the content, climate zone, and existing materials. For example, smart lighting can make a huge difference in efforts to upgrade the performance of older buildings. HVAC controls and new systems can also be revamped. While redoing an apartment in the Watergate complex, a highly energy-inefficient building, however, she had to "go down to the bone" to restore and make more sustainable. "All the systems had to be ripped out."

What Materials and Systems Work for Improving Historic Buildings

Beyond incorporating highly efficient windows, which all experts agreed was a crucial element in a greener building, Casarella made a pitch for geothermal systems, arguing that small-scale system can use the earth's temperature to heat and cool a building with a "relatively light footprint." In addition, these systems only require a "light intervention" in historic buildings. Geothermal means there's no new heavy equipment sitting on exteriors or incongruos solar panels, just a well dug within the building. "Also, there's no noise."

Recycled material surface products are also gaining traction, along with solar-responsive products. Traditional building materials like zinc or tiles are now being manufactured in a more sustainable way. "This is contemporary fashion in manufacturing." 

Reed said operable windows and employee-controlled HVAC systems are basic strategies too (see earlier post on the new Federal building in San Francisco).

However, Owens cautioned that "the next asbestos is already in buildings. We just haven't learned about the negative impacts of it yet." He called for the expansion of newer materials that "are more inert" in terms of their impact on human health. "Mitigating the impact of bad materials is very expensive. Let's try to get it right the first time around."

Ending the Debate

While the National Trust for Historic Preservation has been a leader on sustainability, Casarella argued, "locally there isn't any historic preservation community engagement on this issue." She said there's an "engagement gap."

Reed at GSA thought perhaps it was because there was a lack of easy tools that can be used to value older buildings. In addition, LEED doesn't provide any points for historic value or keeping materials within buildings.  To quantify the benefits of keeping materials within buildings, a lifecycle cost analysis (LCA) needs to be done "holistically" across the entire process, which is difficult to do with older buildings. New tools are needed to educate professionals. Owens agreed that LCA is the approach needed, especially for the "structure or envelope" of a building, where there's the "biggest environmental footprint."

The U.S. Green Building Council argued that in the revamped LEED rating system newly created buildings are at a deficit; existing buildings get a point. However, he agreed that perhaps more can be done to value existing materials and get the buy-in of the historic preservation community. Buildings that replace old buildings have to be viewed as having a "deficit problem," and "should maybe be penalized." For example, a brick is created for a building. From an energy point of view, that brick is a "sunk cost. You can't get it back. The carbon has gone into the atmosphere. There should be a penalty for destroying that brick."

Image credit: Carbon Neutral Historic Rowhouse, Washington, D.C. / Cunningham | Quill Architects