Carbon Priorities and Historic Windows – A Multi-Faceted Approach to Decision Making

Construction is underway on the Vermont Natural Resources Council’s (VNRC) new headquarters in Montpelier’s historic Capitol Complex district. VNRC’s goal is to transform the 1880s-era home on Baldwin Street into a net-zero, low carbon facility by using low-embodied carbon materials including recycled foam insulation, supplemental-cementitious-material (SCM) concrete, and low-embodied carbon drywall; and installing all-electric, fossil-fuel-free heating and ventilation systems. On-site stormwater mitigation strategies add to the project’s demonstration value. With construction partner Neagley & Chase, we are also tracking some construction-phase carbon emissions for a more complete picture of the project’s overall carbon impact.

As with many renovation projects involving historic buildings, the windows pose a challenging question: Do the historic significance and embodied carbon of the existing windows outweigh the operational carbon and comfort implications of not replacing them? Making a holistic decision that takes varying and often competing interests into account is a frequent design dilemma. In grappling with this question for VNRC’s project, Megan customized a process that allowed VNRC to more easily consider both objective and subjective aspects of their project. The process employed an analysis tool she had developed previously and used with various VIA clients to weigh the importance of competing project goals.

  • 11 Baldwin Street, Montpelier – future home of VNRC Headquarters

However, in this case, the process was further enhanced through deeper analysis of the operational and embodied carbon implications associated with the historic window restoration or, alternatively, window replacement.  Megan worked closely with Andy Shapiro of Energy Balance to model six window scenarios and air-sealing approaches that responded to the client’s budget, energy goals, and historic sensitivity.  The energy modeling was informed by technical product data and findings from three published historic window studies.  The six window scenarios ranged from leaving the windows as-is to full replacement using tri-pane casements, and included four incremental restoration/replacement options in between to fill out the field.  Megan mapped these six scenarios and their relative carbon impact and shared the results with the project team.

Megan devised this matrix to guide decision-making around various window scenarios.

By incorporating the results of the window carbon analysis in the previously developed evaluation tool, the client could then identify the most appropriate and balanced approach for their budget and competing project goals. We shared the analysis and findings from the process with the Capitol Complex Commission and the Division of Historic Preservation during the permitting process to help illustrate the reasoning behind these design decisions.  This analysis helped justify the need to fully replace the historic windows, the solution that the reviewing bodies readily understood and accepted.

The outcome was not the highest energy performer, nor the farthest-reaching preservationist approach, but rather it balanced these parameters, which can often be at odds as we work to advance our existing and historic building stock. In this particular case, replacing all the windows with new double hung dual-glazed low-e/argon windows outranked the other scenarios, finding the appropriate balance for this client, building, and neighborhood.

Of course, every project is different and each presents its own unique challenges. We find great joy in identifying a thoughtful, substantiated design strategy by investigating what is most important for each project and how various factors contribute to or detract from the project’s overall goals.

Beyond the Pretty Pictures: Nuts and Bolts Architecture

We are eagerly anticipating the launch of our revamped website which is in its final stages of revision. As you might expect, it will showcase beautiful images of many of our projects. But much of what we do is more understated, though of no less value. Our project palette includes many small and mid-size projects that may not be photogenic, but are worthy of our attention and expertise both to further our mission to address climate change through the built environment and to ensure that architecture and design are available to everyone. Projects involving accessibility, life safety, energy efficiency, functionality, or adaptive reuse of existing structures often fall into this category.


  • Handicapped parking, entrance ramp and stairs at the Hancock Town Hall.

We recently worked on an accessibility project for the Hancock Town Office building, reconfiguring the entry to include a ramp, landing, and stairs to better accommodate all Hancock residents. Our work at Porter Hospital over the last nine years often involves shuffling of rooms, making better use of space, or reconfiguring the inner workings of a department that most people will never see. Likewise, energy efficiency upgrades in walls, basements, and attics are the least glamorous projects, but likely among the most important!

One project we’re particularly proud of is nearing completion. The Middlebury Police Department campus sits on the site of a former wastewater treatment plant off Seymour Street in Middlebury. Various remnants of the treatment plant, including storage buildings and holding tanks, remained on the site and have deteriorated over the years. Since early 2019, VIA has worked with the town of Middlebury on an adaptive reuse project to upgrade several buildings and utilities on the site.

The former sand filter building had been used as a garage but was partially rebuilt and reconfigured to provide much improved parking for five police cruisers. The upgrades improved performance, added insulation and heat, and included a complete new roof structure. Similarly, a large, leaky former control building has found new life functioning as a garage for larger vehicles, a forensics lab, and additional storage. Upgrades included a new insulated roof, windows and doors, insulation, and heating.

  • Repurposed control building
  • Cruiser garage under construction

A driving goal of the re-use project was to make use of the existing infrastructure as far as was feasible and sensible, recognizing the value of these neglected but solid buildings and the energy and carbon they embody as built structures. Repurposing and restoration work is typically more difficult and strategic than new construction, but avoiding complete demolition, subsequent reconstruction, and the associated energy and waste made it a worthy challenge to take on.

Historic Windows – Restore or Replace?

When restoring an historic building, the feature that often proves the most challenging is the windows. VIA must consider a host of factors to help clients determine the best course of action including: their historic significance, the current or intended use of the building, the relevant building science around moisture and energy efficiency, the current condition of the windows, and health and safety factors like the size of the openings and the presence of lead paint and asbestos. Cost is also often of great concern.

We work closely with the Department of Historic Preservation (DHP) to find a desirable solution for each project. Each with valid points of view, the sometimes competing interests of historic preservation, building science and energy efficiency, and the standards of health and safety for the current use, and cost, of course, have to find a balance to achieve the desired result. At the Park House, a former inn that is now a residence for seniors in Rochester, the solution was pretty straightforward. Heavy windows that wouldn’t reliably stay open or open at all prevented residents from accessing natural ventilation. Since the windows were not particularly historically significant, it made more sense to replace them to better suit the current use.

The Park House in Rochester
Deteriorating Slade Hall window.

Sometimes projects are trickier, as in the case of UVM’s Slade Hall, a dormitory designed by McKim, Mead, and White and built in 1928. Given this historic significance, the deteriorating windows posed a thornier problem. Together with DHP and UVM officials, we examined a host of factors to determine whether to restore or replace. After an in-depth cost-benefit analysis and construction of two mock up replacement windows, the team agreed that for the safety of the building’s occupants, the energy efficiency of the building, and the significant cost savings, replacement was the best, if not perfect, solution. One exception with this project is the double-hung, arch-topped window in the stair, which is being reglazed, restored, and will receive a very special exterior storm window.

As always, every historic preservation project is unique. Lovely old windows add character but can be drafty, heavy, or otherwise challenging for today’s standards. They can also be significant historic artifacts that beg restoration to a functional state. It takes a nuanced approach, creative problem solving, and collaboration across disciplines to determine the best solution. VIA is especially proud of its on-going working relationship with DHP and many historic preservation consultants throughout the state. Together we work to balance our clients’ priorities while keeping buildings relevant, well-maintained, well-used, and well-loved for many generations to come.

VIA is Efficiency Vermont’s Commercial Building Design & Construction Partner of the Year

In February, Vermont Integrated Architecture, P.C. (VIA), was named Efficiency Vermont’s Commercial New Construction Partner of the Year. Nominated by Efficiency Vermont (EVT) collaborative partners, VIA garnered a unanimous vote of EVT officials to receive the award. EVT announced this and other awards at its annual conference, Better Buildings by Design. Award winners demonstrate excellence in designing, building, and renovating energy efficient and sustainable buildings.

In the award narrative, EVT noted that “Vermont Integrated Architecture’s commitment to energy efficiency goes beyond its project design work. Sustainability is embedded in VIA’s culture and evident in its buildings. Under the leadership of principals Andrea Murray and Ashar Nelson, the Middlebury-based architectural design firm takes a holistic approach to high-performance building design, weaving in considerations of people and planet while remaining focused on the client’s goals. With an attitude of collaboration, VIA engages all project players to achieve the most efficient design.”
 

Andrea Murray echoed the sentiment, commenting that “We have enjoyed our collaboration with Efficiency Vermont over the years, most recently on the Vergennes Community Housing project and the new Pierson Library in Shelburne. Our close work with Efficiency Vermont ensures that our projects showcase the best strategies for energy efficiency and help advance sustainable design. We are delighted by the honor and look forward tackling new challenges with the support of Efficiency Vermont. We are very fortunate to have this unique utility in Vermont that is championing the challenges architects and builders face with respect to climate change.” VIA has been working with EVT for many years, specifically with a pilot program promoting Net Zero Energy buildings in Vermont. The Waterbury Municipal Center, designed by VIA and completed in 2016, was among the first in the program and helped solidify its viability. In addition, VIA has conducted research into energy modeling software for EVT, and as a result now shares that knowledge with its clients.  VIA also contributed to evaluations of commissioning services, which help ensure that building envelopes and building systems operate optimally for the most efficient outcomes.
 
“This year’s winners are achieving the highest levels of building performance in a state that boasts a statewide network of highly skilled efficient designers, builders, and contractors,” said Efficiency Vermont Director Rebecca Foster. “We are proud to support and celebrate Vermont’s building professionals, who are critical to our small state’s nationally renowned success in bringing the benefits of energy efficiency to all Vermonters.”

VIA House Exceeds Passivhaus Standard

Carothers-Blower-Door

 

The recent blower door test on the Carothers’ new home in the White Pine Lane neighborhood in Middlebury demonstrated that the house exceeds the Passivhaus airtightness standard of 0.6 ach50 (air changes per hour at a pressure difference of 50 Pascals) with a reading of 0.4 ach50.   For comparison, the Vermont energy code requires a reading of 3.0 ach50 while the Vermont high performance building standard is 1.0 ach50.  This result ranks among the best of architect Jean Terwilliger’s work. The test was done prior to the addition of insulation; another test will be run when the house is complete.  You can learn more about blower door tests at the Green Building Advisor website.