Hello Rob,
Thanks for reaching out from the Paris of Appalachia, a moniker for Pittsburgh that I hadn't heard before. I expect that the Net Zero Energy Ordinance is a harbinger of things to come. Its unintended consequences are as well. I know I'm preaching to the choir here, so I will certainly be repeating things you are well aware of.
I recommended caution on seeking exceptions first. It helps paint the picture of "those bad old historic buildings". While there are historic sites where exceptions make sense, the project you are addressing probably does not need any.
Every building, including those achieving Passive House certification, balances load reduction against renewable energy generation. Every project must seek an appropriate balance point. Protecting the character of an historic building, especially one symbolizing the community's heritage of ambition and excellence, simply sets the balance point short of over-cladding. Over-cladding of commercial storefronts in the 50s and 60s is a good source for material on the consequences of over-cladding. As you know, over-cladding has been removed in many downtown revitalizations. (Over-cladding projects are also now being restored. Work by Main Street Georgia comes to mind.)
For a case study, the Wayne Aspinall Federal Building comes to mind, a Zero Net Energy (ZNE) GSA design excellence rehab by then-Westlake Reed Leskowsky (now HDR). The scale and character of Aspinall is very similar to the Pittsburgh building here. That project succeeded by: 1. Carefully minimizing energy demand. 2. Improving envelope performance focusing on windows, roofs, and vestibules followed by wall insulation. 3. Providing a PV array and ground-coupled heat pump system. I see no reason why this approach couldn't work for your building.
I've attached the beta for a very quick and easy carbon calculator that addresses embodied carbon as well as operational. It is the brainchild of Larry Strain from Seigel and Strain in the Bay area. Larry's working title is To Build of Not to Build. With a very limited number of inputs, the spreadsheet develops carbon output data on three scenario: 1. No action 2. Retrofit meeting 2030 zero code targets (80% reduction) 3. Building replacement also meeting zero code targets. The second scenario shows the carbon saving over time from reduced operational energy. The third shows the embodied carbon cost of replacing a building instead of retrofitting. Larry developed this calculator because, as an energy-focused green architect, he came to realize that embodied carbon is really the key for 2020-2050. Near-term carbon reductions matter most in the race to zero. There is lots to talk about on the embedded data in the calculator for another time. Larry is working with a grant and expanded team to convert this to a web-based tool and upgrades to the embedded data and ability to modify it for different projects. I have found 2B/N2B really useful for developing simple case studies that address embodied carbon and give it comparative scale with operational. It opens a lot of eyes.
Lastly, I think the HP community is at an important inflection point. We need to raise the conversation above individual buildings and address policies and programs that make the most sense and focus on the most important factors community-wide, building sector-wide. What does the building stock in Pittsburgh need? Should the focus be on mid-century buildings? How much renewable energy can be generated in the building sector? I am working with the DC Preservation League this year to develop material for the HP community's pro-active recommendations for the DC Climate Action Plan. When you start to look sector-wide, it puts battles like the one you have in perspective. I hope our work will become a model. I'd be happy to talk with you more about our work in DC.
Thanks for working to make sense out of well-intentioned climate action initiatives made by people with too little understanding of what it takes to act appropriately as stewards of buildings, including heritage buildings.
Best regards, Carl
Carl Elefante
m 301-325-3266
Quinn Evans
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