Think Historic Buildings and Renewable Energy Can’t Mix? Think Again
By Caitlin Jones
5 min read
Tax Credit Advisor, August 2009: Thinking of installing a renewable energy system in an historic building?
The concept may sound impossible, even ludicrous, particularly for a renovation project seeking to qualify for the federal historic rehabilitation tax credit.
But these kinds of rehabilitation projects are possible, with the right building and approach, according to experts.
“It’s going to work in some buildings, in some rehab scenarios, and it’s not going to work in others,” says Washington, D.C. historic preservation consultant William MacRostie, a principal of MacRostie Historic Advisors, LLC.
By far, the most popular type of renewable energy system being installed in historic buildings is solar. Here the most common installation is a solar photovoltaic (PV) system, where solar panels collect solar energy to produce electricity for use in the building. Less common is solar thermal, where energy collected by solar panels is used to heat water. Both types of installations qualify for the federal investment tax credit, which is claimed entirely in the first year and equal to 30% of the cost of the installed system.
Out of Sight Is Key
“Sightlines are a huge issue” when designing a solar array for a building seeking the historic tax credit, says Boston area architect Clifford Boehmer, a principal of Mostue & Associates Architects, Inc., Somerville, Mass. This generally means, according to Boehmer and MacRostie, designing the solarinstallation so it won’t be visible from the street or any public right-of-way. According to the pair, the most promising candidates are buildings with a flat roof, and the taller the building the better.
The ideal, MacRostie adds, is a flat-roofed building with a parapet. A parapet is an extension of the building’s exterior wall above the roof line. This permits even greater concealment of renewable equipment such as solar panels installed on the roof.
Concealment of solar panels or other renewable energy equipment generally is necessary to win review approval of the renovation plans for an historic rehab project from the National Park Service, and to comply with the U.S. Department of the Interior Secretary’s for Rehabilitation. Rehab plans must also pass muster with the state’s historic reviewers, in the state historic preservation office (SHPO).
“The historic credit world is all really visual impact-driven,” says MacRostie.
MacRostie and Boehmer said it’s tough to design and install a solar energy system on a building with a sloped roof and obtain the requisite Park Service approval to obtain the historic tax credit.
Besides installation on a flat-roofed building, another possibility is to locate the solar system at a nearby building that isn’t part of the historic structure, or on another part of the site. But even here care must be taken so that the installation isn’t visible or detracts from the historic appearance or character of the building.
Boehmer said his firm is working on an historic tax credit project in Boston’s Beacon Hill neighborhood, in which three existing historic masonry buildings used as a rooming house will be renovated into 115 single-room occupancy dwelling units. Panels for a solar hot water system will be installed on a flat roof at the development, called Bowdoin Manor.
Wind, Geothermal
The experts said it’s virtually impossible to incorporate wind energy production equipment à say mini-turbines à into an historic tax credit project, because of the high exterior visibility of this equipment.
Another, less intrusive possible renewable energy resource for historic buildings is geothermal, which can also qualify for energy tax credits. Geothermal systems depend on the circulation of water through pipes to supply the heat and/or air conditioning for a building. The physical equipment is located in the building’s interior, and the necessary pipes run through one or more wells drilled into the earth. The visible exterior signs of the latter are manhole-like covers that cap the wells and are typically located on the ground outside the building.
Advice for Proceeding
The experts offered some advice to developers or building owners thinking of incorporating a renewable energy system in an historic tax credit project.
MacRostie suggested a good first step is to discuss the concept with reviewers at the National Park Service and SHPO, to get their view on whether such a project seems approvable.
Boehmer also favors holding a “green charrette” at the outset of the planning process for a project. This is a meeting where all of the key parties to a project get together to talk and brainstorm à the developer, architect, engineer, historic preservation consultant, renewable energy specialist, general contractor, and others. “That’s a very good preliminary strategy,” Boehmer says, “to have a big meeting with everybody sitting around the same table and run through all the different options and decide what’s appropriate.”
Architect Sharon MacNulty, a colleague at Mostue & Associates, says an initial meeting can also help “flush out” possible conflicts between the strict historic preservation standards and the requirements to qualify for funding sources for the energy equipment or building. For instance, she noted that to qualify for financing from the Massachusetts Technology Collaborative for a rooftop solar PV system, the project and building must meet Energy Star standards. “But if you’re preserving your exterior wall finishes and if you’re keeping historic windows, there’s no way to meet the Energy Star requirements,” she says. “So right away you’ve missed out on one of the major pre-requisites for the funding.”
