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Solar panels for historic structures

  • 1.  Solar panels for historic structures

    Posted 02-11-2019 15:34

    Since Chris Warren's 2013 article, "Powering Historic Buildings," have solar panels been installed on any NTHP properties? If so, what considerations did NTHP take into account when deciding whether solar was an appropriate alternative? Have any formal guidelines been developed?



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    Helen Harrison
    Director
    Pollock-Krasner House and Study Center
    East Hampton NY
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  • 2.  RE: Solar panels for historic structures

    Posted 02-11-2019 16:42
    In Washington, DC, the Department of Energy & Environment recently developed sustainability guidelines for historic properties in consultation with the Historic Preservation Office. The guidelines include information on solar panels. They're in draft form right now, but they may be a good reference for you: https://planning.dc.gov/node/1314201

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    Raina Regan
    Senior Manager of Easements
    National Trust for Historic Preservation
    Washington, DC
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  • 3.  RE: Solar panels for historic structures

    Posted 02-14-2019 10:55
    Raina, thank you for sharing the draft sustainability guidelines for DC. The document looks beautiful and very useful. The live links are super.
    I would say, though, from personal experience, that there are a couple of important things missing​:
    Sensitively-designed exterior storms can be very unobtrusive and useful on historic window openings. I have both custom wooden and powder-coated aluminum, and the look and performance is very good.  As long as one is not interested in closing shutters, they work well.
    There should be a bit more on the realities of replacement "insulated" windows in the document, or perhaps a reference link to a more focused document (I know they have a stand alone window guide).  There has been good research in recent years by a collective that formed under the Preservation Trades Network that would be a valuable addition to the references, as well as the Scottish window study publications.
    They should add interlocking zinc or bronze metal weather-stripping for wood window sash to the topic discussion and tables. I have dealt with many window systems as a consumer, vinyl and historic, and this method is hands-down the most efficient in cutting drafts. Not brushes, not bulb gaskets, not either of them combined with storms.


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    Debbie Martin
    City of Wilmington
    Wilmington DE
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  • 4.  RE: Solar panels for historic structures

    Posted 02-11-2019 17:57
    One of the many merits of traditional euro standing seam:  you can install things on the roof (solar, walkways, etc etc...) with seam clamps which leave the roof completely in-tact, and fully functioning.  no penetrations and no goop!  extreme life cycle.  panels independently repairable in case of damage..

    showing how solar could be integrated without damage to roof

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    Kurtis Hord: Architectural design / Lime putty masonry / Pattern making / European guild-influenced roofing
    tradroofing.com / (412) 228-0241
    all honor to god / the meek and humble shall inherit the earth
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  • 5.  RE: Solar panels for historic structures

    Posted 02-11-2019 18:00
    also, of note: the tesla roofs are beautiful.  combined with good design for the flashing (which they are lacking) i see this as wholly appropriate for pitched roofs that would be visually impacted by the look of solar.

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    Kurtis Hord: Architectural design / Lime putty masonry / Pattern making / European guild-influenced roofing
    tradroofing.com / (412) 228-0241
    all honor to god / the meek and humble shall inherit the earth
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  • 6.  RE: Solar panels for historic structures

    Posted 02-15-2019 10:38
    We are a preservation organization working to expand solar power generation in Massachusetts. This is part of our "Adaptive preservation strategy" which we see as part of upgrading the technology in our historic neighborhoods to meet the challenge of climate change.

    Because of the aesthetic issues we are in most cases recommending that solar collectors not be installed on historic structures, other than those where flat roofs make the collectors invisible to observers. Instead we are advocating for creation of "Community solar" installations either on rural sites or on some of the many commercial roofs that exist in every community. Given the constraints on solar panel net-metering this should be adequate in many situations.

    At the same time the "Building integrated photo voltaic" products now being introduced by Tesla, Forward Labs, and others have a lot of promise to be much more architecturally appropriate, and should be explored and vetted for aspects such as flashing adequacy.

    We are advocating that historical and architectural review commissions should oppose intrusive solar installations, and should instead support adoption of 'Community solar' as an option, and at the same time wait on allowing rooftop installations until appropriate products are generally available.

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    David Gaby
    Springfield MA
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  • 7.  RE: Solar panels for historic structures

    Posted 02-12-2019 12:49
    The Presidio of San Francisco (administered through the Presidio Trust) has been very careful about how and where solar panels maybe installed. As the property is a National Historic Landmark, the NPS comments on all building alterations. Many of the buildings are white, Mediterranean-style with sloped, red-clay tile roofs. Below is a clip regarding a request for proposals for use of Fort Winfield Scott. In general, based on public hearings, the Trust is reluctant to place panels on roofs, and in contexts where they will be seen from public view, and have been move amenable on those with parapets or replacement buildings.

    Can solar panels be installed on building roofs?
    The Presidio Trust uses the National Park Service's 2011 document The Secretary of the Interior's Standards for Rehabilitation & Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings to evaluate proposals for sustainable design elements in historic rehabilitations. Generally speaking, the recommended approaches in that document for the installation of solar panels are not achievable with the building types and site conditions at Fort Winfield Scott.

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    Susan McComb
    San Francisco CA
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  • 8.  RE: Solar panels for historic structures

    Posted 02-12-2019 15:28
    Our Historic District Commission has 'test' approved two solar panel installations in German Village, a National Register Listed district of 1700+ structures in south Columbus, the oldest district in the state.  Our city Historic Preservation Office provided the Commission with the Sec. of Int. Sustainability Standards in their application packets for the meeting even though they have not been formally adopted by City Council. We await the inclusion of these standards in an upcoming Guidelines update so that property owners have consistent reference points on the subject.

    We have approved synthetic slate material for roofs, perhaps a precedent paving the way for Tesla solar roofing material.

    Hope this context helps!

    Nancy

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    Nancy Kotting
    German Village Society
    Columbus OH
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  • 9.  RE: Solar panels for historic structures

    Posted 02-13-2019 12:14
    Synthetic slate is a terrible product.  Petroleum based.  Life cycle no better than other short-sighted roofing options.  The operations required to install synthetic are mostly the same, so you still assume most of the hand nailing labor cost, however you make a tradeoff for a disposable product, for a very small percentage of gain in material price.  The main hurdle in real slate, is training the folks who are on the roof nailing to be 100 percent honest with themselves about every single action of their hammer, and with culling.  When I'm putting on slate I like to assume the mindset that god is watching everything, and any mistake or miss-step will result in eternal torture.  It's really hard to find folks who are willing or even able to work under such conditions (have you met most roofers?) so I understand why we have synthetic, but you're not really gaining anything by applying it other than a very temporary aesthetic that will fade, and have to be re-roofed at compounding expense each time.  Natural slate, done properly can and should last the entire lifespan of the building.  The problem is again finding the folks who have the integrity to cull each piece, and self monitor while installing to ensure they don't overnail or over stress in the process.

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    Kurtis Hord: Architectural design / Lime putty masonry / Pattern making / European guild-influenced roofing
    tradroofing.com / (412) 228-0241
    all honor to god / the meek and humble shall inherit the earth
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  • 10.  RE: Solar panels for historic structures

    Posted 02-14-2019 08:38
    ​Synthetic slate discussion: Kurtis, I like your response, but you have left out the fact that the fasteners and flashing have shorter lives than the slate.  This is usually the point in time where we are approached to accept alternatives.  I have used plastic slate samples as temporary stepping stones in my front landscaping :) The weathering is interesting, even though it is not their intended use.

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    Debbie Martin
    City of Wilmington
    Wilmington DE
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  • 11.  RE: Solar panels for historic structures

    Ambassador
    Posted 02-18-2019 18:00
    As much as I love old buildings of any style, I do not agree with prohibiting, or even significantly limiting, the installation of solar panels or solar roofs in ways that would impair their efficiency. We must all do everything we can to protect future generations from global warming, and historic buildings should not be exempt from the effort.  These buildings have evolved since their construction, albeit slowly in most cases, and should not be prevented from evolving now, if the adaptations are reasonable, and beneficial to the building's occupants and to larger society.  A Federal house with solar panels is still a Federal house.

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    Jim Sparks
    Glasgow KY
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  • 12.  RE: Solar panels for historic structures

    Posted 02-22-2019 01:34
    Debbie, thanks for your reply.

    Agreed with you on the "flashings".  My early work was all 3 story brick from late 19th c, all with built in gutters and complicated "victorian" rooflines.  The slate in all these cases was more than durable and had at least another 100 years of service life as it stood.  The use of terne for almost all residential roofing work in that period was a major blunder, for sure.  These old valleys, and cornices are the major reason we lose good slate roofs as they make up a majority of the cost (along with access).  And a building owner faced with a 30-50k bill for "gutters" and no restrictions will see it as frivolous.  I have however been ruined by collaborating with europeans...  where that architecture style was stolen from..  and they don't suffer these problems because they kept guild practices.  The market drove american roofers in that age to use terne, and solder.  These practices were strictly forbidden over there (solder especially, because they knew their origami).

    Acknowledging this blunder should not take away from what it could be: if approached properly.  Permanent roofing with extreme life cycle and infinite repairability in kind.

    My repair/restorations of historic roofs centered on Louisville, KY and later the northeast.  I have never seen an old roof where nails were failing in any significant way.  The exception to this would be in roofs installed later, in romantic revival periods (1920-40) where they started using a technique called felt lap (terrible).

    With properly guided repair: valleys and flashings can be upgraded to euro guild spec, and most durable varieties of slate can truly last as long as the building itself; which should be the goal of any roofing endeavor, if we are truly honest with ourselves.

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    Kurtis Hord: Architectural design / Lime putty masonry / Pattern making / European guild-influenced roofing
    tradroofing.com / (412) 228-0241
    all honor to god / the meek and humble shall inherit the earth
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