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Do the new NPS Sustainability guidelines ease the task of integrating sustainability into the fabric of preserving historic buildings as intended?

Posted by MacRostie Historic Advisors on Tuesday, December 16, 2014
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Review of New NPS Illustrated Guidelines on Sustainability - Albert Rex

National Park Service (NPS)

The Architectural Team (TAT) principals Bob Verrier, AIA, NCARB and Michael Binette, AIA, NCARB, recently published a detailed analysis on the new guidelines from the National Park Service (NPS). Their article raises the question: Do the new guidelines ease the task of integrating sustainability into the fabric of preserving historic buildings as intended? If so, why are owners and developers of historic structures more concerned than ever about varied interpretations by federal and state reviewers“ and how those could affect certifications for LEED and model energy codes?

As Binette and Verrier write in the online exclusive for EcoStructure magazine, design solutions for creating buildings that meet NPS review and green building certification demand experts with a command of the letter and spirit of preservation standards. We also need to bring project owners and developers the ability to anticipate, address, and argue issues raised by evaluators.

Having completed over 150 historic adaptive reuse projects over the firm's past 40 years, TAT is frequently sought out for their expertise by project owners and developers. MacRostie Historic Advisors has collaborated with TAT on numerous historic redevelopment projects, most recently the award-winning Bourne Mill Apartments in Tiverton, RI developed by EA Fish Associates, which involved the conversion of eleven separate buildings located on the abandoned mill complex into a new 165 unit mixed-income multifamily development.

BACKGROUND Preventing old buildings from being torn down is a key aim of historic preservation. We want to preserve our historic fabric so that future generations can experience the places and buildings that informed (our) past. In the past, preservationists have been accused of keeping buildings frozen in time, with a mission often seen as conflicting with the emerging green building movement, and its focus on new and energy-saving technologies.

This isn't the case today, write Binette and Verrier. Organizations that champion historic preservation and those that champion green building now largely embrace each other's missions. It's widely accepted that historic buildings are inherently sustainable, and that embodied energy is an important calculation used alongside evaluations of energy efficiency to determine overall environmental impact and carbon footprint, says Binette.

Yet the EcoStructure article identifies critical challenges that have arisen after new federal rules have been enacted. The National Park Service (NPS) guidelines – unveiled in April last year by the agency that oversees the Federal Historic Preservation Tax Incentive program “are meant to improve opportunities for saving historic structures while also making them lean and green," says Verrier in the article:

To bridge the gap between attaining historic tax credits and the criteria for LEED certification and similar green standards, savvy building owners and developers are working with experts well-versed in the preservation standards. These experts can help anticipate, address, and argue issues raised by evaluators, especially when they affect the sustainability or energy profile of the buildings – or worse, when they actually put a project's feasibility at risk.

According to the EcoStructure article, the NPS guidelines allow flexibility in how the unique conditions of individual buildings can be addressed so that preservation efforts can be aligned with today€™s energy codes and standards,” while it also “recommends certain paths to maintain a building's historical status and significance, and dissuades the use of others.

According to the NPS, the Federal Historic Preservation Tax Incentives program – which offers a 20% tax credit for qualified historic preservation projects “ is the federal government's largest revitalization program, and has helped assemble $58 billion in private-sector investment for at least 37,000 building projects. Many states offer similar incentives that may add as much as 10% to the tax breaks.

The new NPS guidelines replace more specific, prescriptive guidelines. "But this new flexibility means that different reviewers“ from both federal and state agencies“ may have different opinions," says Binette. In the EcoStructure article, Binette and Verrier recommend various means for meeting the NPS guidelines while also meeting programs such as LEED. Examples of key building systems and products include fenestration and insulation.

Especially for older masonry buildings, adding insulation boosts energy efficiency of historic properties dramatically. However, Adding insulation invariably changes how a building responds to a host of internal and external environmental conditions, most notably moisture, Verrier writes. Condensation or moisture vapor can accumulate within the newly insulated building envelopes because they will be tighter than anticipated by the original designers and builders.

If project teams don't take these changes into account, say the authors, the historic structures can suffer from mold, spalling bricks, damaged façadds and other problems.

Again, however, with the proper engineering, an insulation upgrade is the singular most effective and least expensive way to improve energy efficiency. Also, new insulating technologies are being developed at a rapid clip. So far the NPS permits most, including certain treatments with spray-applied products that – once installed – could even with some effort ultimately be removed and the original surfaces restored. This, like other technologies, requires expertise and evaluation.

As for windows, preservationists tend to see window replacement as the least preferred solution. At the very least, window profiles should not be altered to retain the original architectural fabric.

LEED fails to acknowledge that historic windows are important features and that their energy efficiency can be upgraded, according to the Whole Building Design Guide (WBDG), published by the National Institute of Building Sciences. Employing storm windows, proper weatherstripping, and caulk, original window systems can achieve efficiency similar to that of new insulated glass window systems.

Verrier and Binette offer these ideas in the EcoStructure article:
While this is often true in most cases, there are projects which window replacement is necessary. Technically speaking, the ability to save a historic window over the long term is often very limited given the costs “which are often unavailable“ of de-leading and restoring the wood frames and sash and then maintaining them over the long term.

For buildings that have been abandoned or neglected for decades, replacement windows are often the only viable option. In these cases, the fine points such as what type of replacement window systems, or whether insulated glass is appropriate must be sorted out with reviewers to strike the right balance between energy savings and architectural authenticity.

The forward strides made by the NPS should be beneficial to developers interested in rehabilitating historic buildings. More flexible guidelines mean more access to tax incentives and more private investment.

But with the new guidelines come a greater need to plan, understand, and engineer projects that balance modern energy efficiency with the goals of historic preservation. Successful developers and owners are working with project teams that not only provide creative architectural and engineering solutions but that also can understand and navigate the increasingly complex issue regarding legislative, code, and tax nuances.

About The Architectural Team, Inc. - Founded in 1971, The Architectural Team, Inc. is a 60-person master planning and architectural firm that has grown through its design excellence and commitment to responsive and collaborative client relationships. The firm has developed a portfolio of distinctive design solutions for a broad range of building types and programs, and has earned more than 75 awards for design excellence. These include the new construction of large urban mixed-use developments, residential, commercial, hospitality, recreational, and academic facilities, as well as a national reputation in the area of historic preservation and adaptive reuse. The firm is located in the restored 1840s-era Commandant's House in Chelsea, Mass. Visit the firm's website here.

About the Blogger – Albert Rex is the Director of the Northeast Office of MacRostie Historic Advisors. Albert has been active in preservation and real estate in New England for the past 17 years. Read more about Albert here. Bourne Mill photo courtesy of © Nat Rea