Projects, Design

Considerations for Retrofits and Adaptive Reuse

Millions of square feet of vacant building space have been on the minds of architects and developers even before the pandemic added a significant number of office settings to that total. While retrofits, adaptive reuse and additions are an attractive solution, historical requirements, codes, structural limitations and client requisites can quickly generate a to-do list that can send anyone back to the drawing board to design a new structure instead.

While those challenges are formidable, the teams that embrace retrofits and adaptive reuse are checking off each while bringing rejected buildings back to life to deliver exciting new experiences. Here are ways to address those retrofit roadblocks:

Call on expertise early
“The owner and architect will zero in on the biggest budget item,” says Bill Wilder, director of technical sales at Graham Architectural Products, an Oldcastle BuildingEnvelope brand. “To fix a façade, you have to invest in the windows and doors, and windows are often the biggest expense.

By bringing in the window manufacturer early, the architect can benefit from that expertise to ensure the window product will meet the specification. This is particularly important for projects aiming for historic tax credits.

It’s easy to fall in love with a very competitively priced product, only to learn that it can’t be approved by the historic approval body. That review and approval process can take 30-60 days, and each tweak to the product adds up. Something that should’ve taken 2 months can push the project 6-9 months behind, and the expected financial savings have eroded due to the customizations needed to meet approval. A window manufacturer with experience in historic projects can help ensure the specified product can be approved in a manageable timeframe while meeting thermal, structural and aesthetic requirements.

Window manufacturers providing window proposal drawings that can be imported into the architect’s drawings offer an important service. “This can be particularly beneficial for historic projects when the company accurately replicates the details of the original windows and provides a side-by-side comparison with proposed windows to resolve any issues,” Wilder explains.

Capture energy performance
Those drawings can be combined with calculations to help identify how to maximize thermal performance. While retaining the original façade appearance is often an important requirement for retrofits, it can limit the glass options. This can be because a clear appearance is required on historic projects, or profiles and sightlines are difficult to match. Window manufacturers will have different options for thermal breaks and can also customize the package based on the tear out, how the opening will be sealed, etc.

As we create systems that improve energy efficiency, the limitations we sometimes confront in retrofit projects shouldn’t negate exploring ways to reduce a façade’s carbon footprint. Again, this is an opportunity to capitalize on the expertise of companies like Oldcastle, which has a whitepaper devoted to carbon in commercial fenestration.

“Operational carbon is driven by the performance specifications of the fenestration, carbon intensity of the heating and cooling systems, and local weather,” explains Billy Strait, CSI, VP Business Development at Oldcastle. “Embodied carbon is driven by the aluminum recycled content and source of primary billet along with the ratio of framing to glass. When a holistic view of the manufacturing and use phase of an aluminum fenestration system is considered, it is possible to minimize both operational and embodied carbon in a way that provides the best environmental benefit.”

A closer look at historic restoration: The Battery
Upon completion of its adaptive reuse and addition, the former power station of the Philadelphia Electric Company on the Delaware River – now known as The Battery – will offer event space, hotel, apartments, commercial space and more.

The project hit a snag when the team identified damaged concrete surrounds in the 40-foot openings, each of which house 12-15 windows.

Architect Christopher Kenney, AIA, LEED AP, CSI, Strada, LLC, was staring down a problem that threatened to become as large as the “absolutely enormous” windows.

The Battery Retrofit

GAP pivoted to replicate the concrete surround detail in its custom “unitized” subframe, which also enhanced water management and created efficiencies for the installation while improving thermal performance.

GAP utilized a similar unitized system for The Battery addition, then delivered the factory assembled unitized receptors and window units directly to the panel manufacturer so the entire unit could be assembled and sealed for efficient installation.

“It’s been a privilege to work on this project, and the GAP team played an important part in its execution,” Kenney says. “Their knowledge of historic windows is absolutely top-shelf.”

Consider customizing
Don’t equate “custom” with “expensive” before examining the big picture. A custom unit can deliver multiple dividends across the assembly and installation. For example, by creating custom window systems for The Battery, expenses were recaptured for the customer and risk was reduced in many areas by:

    • Maximizing thermal performance
    • Eliminating trim and structural steel
    • Eliminating some carpentry on-site
    • Fabricating and assembly of the unitized receptor sub-frames in the factory to:
      • Reduce labor costs of assembling in the field
      • Keep the full warranty with one company

In addition to improving project success and efficiencies and reducing risk and surprise expenses, the evolution of window solutions for retrofits and adaptive reuse projects is helping architects and developers reduce building inventories and preserve the past – as well as the environment – in our communities.

Connect with an Oldcastle BuildingEnvelope expert or learn more about Graham Architectural Products’ retrofit, adaptive reuse and addition window solutions at