Retrofits for Energy and Cultural Preservation
Maryruth Priebe, Senior Editor
New, certified green buildings may offer sex appeal and flashy style, but older buildings offer unexpected benefits to cost-conscious businesses and homeowners. The older the better!
Buildings account for 39% of America's energy consumption, totaling 6.5 billion barrels of oil annually. If we could drastically slow the flow of fossil fuels to this sector of our economy, it would go a long way to shrinking our mammoth carbon footprint and reducing the negative impact of $1 Billion a day spent on oil imports. The many perks of retrofitting are what those in the historic building preservation community have been waving their arms about for decades. World events -- from the economic downturn to catastrophic natural disasters -- are creating a surge of interest in boardrooms, architectural firms, and certifying agencies for the restoration and retrofit of old buildings.
The move toward a preference for retrofitting is no more evident than in corporate investment trends.
Despite the financial slowdown, 50% of firms surveyed globally, in a recent McGraw-Hill Construction poll, said they had a commercial retrofit planned to start before 2015, and they're set to reap the benefits. The report adds that firms that have retrofitted saw a 9% operating cost reduction over one year; the savings are 13% over five years. Additionally, these companies anticipate receiving an increase in building value between 4% and 5%. What's more, when compared to an 8 year payback for new construction, the payback for a retrofit takes less time.
The quintessential example of such benefits is the $20 million retrofit of the Empire State Building. It has resulted in a reduction of energy consumption by 38% and savings of $4.4 million in energy costs annually. Clearly the energy and building valuation benefits of retrofitting make sound business sense, but that's not the only bottom-line reason for choosing old over new. One of the lessons the green building industry is learning is that old buildings often outperform new ones --even those built to high green building standards. Though it depends on the era in which a building was designed and constructed, several studies have recently confirmed that old buildings can be incredibly energy efficient, giving new meaning to the maxim that the greenest building is the one already standing.
Perhaps the most striking piece of evidence for this fact comes from the recent PlaNYC New York City local Law 84 Benchmarking Report (August 2012), which is a recounting of the annual energy of all privately-owned large buildings (over 50,000 square feet or properties with a combined square footage of over 100,000 square feet). These self-reported numbers reveal something interesting: older buildings of every shape and size report better performance in terms of both energy and water consumption than buildings constructed in recent decades.
"The numbers are clear: The most energy efficient buildings are older buildings," explains Francoise Bollack, architect and president of the Historic District Council in New York, referring primarily to pre-WWII construction. "It's basically validating what we have been saying for many years: older buildings tend to be more efficient because they have more mass. By their very nature they are more insulated."
The report shows that on average, older buildings achieved higher ENERGY STAR scores than newer buildings, with energy use per square foot increasing for each 20-year group dating back to those built in the 1900s. The authors of the report attribute this largely to extensive use of ventilation systems, more efficient thermal envelopes, and less dense occupancies, though they acknowledge that more research is needed before they can draw firm conclusions. Though these older buildings are already more energy efficient, there is still room for improvement, especially given that these large buildings account for 45% of the city's total carbon emissions. The report authors estimate that if the most inefficient buildings were to improve their efficiency to only median energy use intensities within their building category, they would put an 18% dent in New York City's energy consumption, and reduce greenhouse gas emissions by 20%. This report and others like it are making the business case for preserving rather than demolishing old buildings.
As Bollack put it, "As we get more and more professionals who are able to get this data, it's actually going to be less of a shouting of opinions and more of an informed discussion."
What's more is the fact that retrofitting of old buildings stimulates local economies and generates jobs.
"To our delight, we've been seeing a lot of local labor involved in restoration. Rather than getting drywall from god knows where, it stimulates the local economy by reusing materials," comments Simeon Bankoff, executive director of the Historic Districts Council in New York.
Another report, put out by Deutsche Bank and The Rockefeller Foundation entitled "United States Building Energy Efficiency Retrofits: Market Sizing and Financing Models," paints a pretty rosy picture. The report concluded that, over a ten year period, a $279 billion investment in retrofits of commercial, residential, and institutional buildings would provide:
- 3.3 million new job years, or an average of 330 thousand jobs a year.
- $1 trillion in energy savings.
- Reduction in countrywide energy savings of 30%.
- Cut in Greenhouse Gas emission by 10%.
Retrofitting historic buildings also reduces a building's climate impact by preserving its 'embodied energy' -- that is the energy required to build it in the first place -- along with that needed to take it down and remove debris. Embodied energy includes all phases of the value chain: extraction of resources, manufacturing of products, transportation of materials, and installation of the building.
Bankoff pointed out, "After the hurricane [Sandy], we saw clearly just how much stuff is left behind when buildings are demolished, and it all has to go somewhere."
Patrice Frey, Sustainability Director at the National Trust for Historic Preservation, and Brad Kahn, president of Groundwork Strategies, and contributor to Preservation Green Lab, which is part of the National Trust for Historic Preservation, had this to say:
"People interested in environmental performance are beginning to understand there is a lot of embodied energy in existing buildings, so demolition and new construction can frequently have significant environmental impacts, even when the new construction is more efficient."
Today, most building and environmental scientists look at embodied energy in terms of the impacts that are avoided by not constructing a new building. In the case of residential homes, the estimate for recovering the carbon emissions invested in the building is between 35 and 50 years. That means leaving an old building standing and retrofitting for energy efficiency is much greener in the long run.
Reducing utility costs, creating jobs, lowering greenhouse gas emissions, and preserving embodied energy are all very solid justifications for choosing to retrofit old buildings, yet there are many other reasons why this is a great choice. We preserve buildings for their aesthetic contribution to our communities and as a way of sustaining neighborhoods.
"Community development and preservation have a lot to do with people's control over their environment and not a developer's control over their environment," explains Bollack.
So what features stay and which ones go when retrofitting historic buildings?
Older Building Efficiency
Pre-WWII buildings employ some very energy efficient designs that are usually kept during the renovation process, including:
- Natural ventilation and operable windows,
- Passive heating and cooling,
- Passive survivability (the ability to function without energy input for key functions in emergencies), and
- Minimal heat loss from exterior walls due to close adjacency to other buildings.
First on the list to be upgraded is usually insulation and heating fuel type. As Bankoff explains:
"In the older rail houses, brownstones and commercial buildings, we make sure the attic is insulated and windows are operable, which saves a lot of energy. Also, it's important to put regulators on heating systems and make sure they're up to date and working. If you have one that uses terrible crude oil, you'll want to update it into a boiler system."
Additionally, an unglamorously big opportunity is that of caulking. "People don't pay attention to caulking, but buildings often have a lot of holes that don't get plugged," says Bollack. As important is the issue of through-wall or window air conditioners. "People forget that these units amount to an 8" by 8" opening in the wall. That's big because you're losing heat in the winter, and in the summer you get heat gain." Overcoming this is a challenge for both old and new buildings. The options include redesigning the building with cross-ventilation and operable windows, or installing central air conditioning, which has its own inefficiencies. Again, that's where pre-WWII buildings have the leg up; most are designed with cross-ventilation principles fully integrated. After WWII, air conditioning and mechanical ventilation became so popular that more modern buildings completely depend on mechanical cooling. "We can learn from old buildings."
Bankoff further explains: "œIt's the stuff that was built post-WWII that's not as flexible; they're just not as robust." Examples are mid-20th century buildings designed with glass curtain walls, especially when they're not well maintained. "Curtain walls can't control airflow as well as they should."
Additionally, a 1960s cooling and air system is not very efficient, often requiring an update.
Windows: Replace or Fix?
An issue that often creates tension within the historic building retrofit space is how to treat old windows, according to Bankoff. "Ten years ago there was a lot of ripping out of all the old windows and putting in new ones." By and large, most energy efficiency experts argued strenuously to replace old windows, while those in the historic preservation camp fought hard to preserve them. The good news is that people in this field are "getting more savvy." Bollack explained that her firm has been engaged in preserving several 1920s buildings with single-glazed, steel encased windows. Before they get started, they hire an environmental consultant. As a result, more recently most have recommended against replacing the windows, saying that it's often better to increase insulation and burn better oil than rip out old windows. "This isn't about preservation, it is about the numbers."
By re-using existing windows, retrofits such as adding storm windows and insulating blinds can improve energy performance at a fraction of the cost of new windows.
Frey and Kahn add: "While energy companies continue to push new windows, the reality is that nearly the same energy performance can be achieved through retrofits, at a much lower cost."
Woodlawn Mansion, a house that was part of George Washington's Mount Vernon and today the first historic site owned by The National Trust for Historic Preservation, is one such example. This 126-acre estate, constructed between 1800 and 1805 and later restored by playwright Paul Kester in 1905, recently finished a partial window restoration project. The process involved treating deteriorated Aquia sandstone sills and lintels, preserving wooden frames and sashes, reinstalling shutters, and painstakingly removing 30-year old UV film. While there are tremendous opportunities for energy savings that don't trample on our historic building treasures, certifications like LEED are sometimes not practical.
Applying a 'green' standard to a building that's already standing can tie the hands of designers, forcing them to make choices that fit within a particular philosophy when other, more well-suited solutions could save more energy.
Performance Based Guidelines
As a result, there are those within the retrofit space who are pushing for performance-based guidelines and legislation for historic buildings.
"Performance based design gives developers the flexibility needed to achieve specific, measurable outcomes without being tied to narrow proscriptive requirements," according to Frey and Kahn. "This is key to improving the environmental performance of existing buildings while maintaining integrity of the building and its context in the surrounding neighborhood."
Typically, older buildings were designed with the local environment and culture in mind. That means that, by default, architects designed energy efficiency into structures. New green building standards often focus on high-tech systems and 'gizmos' for attaining energy efficiency -- systems which may not add much value to the original design. "There is much that we will learn from older buildings," according to Bollack. The Anhalt apartments on Capitol Hill in Seattle is one example of how performance standards, regulated by local conditions, can work. Originally built between the 1920s and 1930s, the apartments were converted into offices in the 1970s, but a new retrofitting scheme will transform the old building back into residential space with 24 apartments. This is good news for the building that was recently designated a historic landmark. The features that will be preserved in this 21,600 square foot, three-story brick building include the exterior brick clinker masonry, decorative stucco, fenestration, and half-timber detailing. Additionally, the Tudor-style stair tower and courtyard entry will also be preserved. The energy retrofit will be designed around the city of Seattle's outcome-based energy model (a project developed in conjunction with Preservation Green Lab), which will allow for flexibility in how the building is retrofitted. Strategies will be dictated not by a particular green building philosophy, but rather by the highest return on investment, combined with the requirement to conduct post-construction monitoring to ensure energy reductions are achieved. The hope is that this outcome-based scheme will become the basis for a similar national model. Designers have strategized extensively regarding the efficient design of new buildings, but clearly more thinking is needed in the historic building space, especially given the important role existing buildings will play in the fight against climate change. Let's hope the sustainable building community spends as much if not more energy on concepts like performance-based retrofits in the years to come to seize the opportunities embodied in old buildings.
As Bollack and other historic building preservation advocates have been saying for years; "It makes environmental sense to preserve the buildings "¦ demolishing is so fabulously un-green."