Q&A: Peter Arbour, Founder of Liquid Wall

A rendering of a Liquid Wall erection scenario.

Peter Arbour, RA, is founder of the Arbour Group and inventor of the Liquid Wall facade, a unitized curtain wall that replaces aluminum with ultra-high-performance concrete (UHPC). Arbour has been the recipient of several grants awarded by NY State, and was selected for the highly competitive cohort of the Venture for ClimateTech program in 2024. The Liquid Wall has also received development funding from NYSERDA, and Arbour was recently awarded the Jeff Lawrence Innovation Fund Manufacturing Grant from the Albany-based business development service FuzeHub. Arbour is working in collaborative partnership with the Center for Architecture (CFA) and the American Institute of Architects in New York. The Fuzehub grant of $65,000 is designed to encourage collaboration between not-for-profit organizations such as CFA and small- to medium-sized manufacturing companies in New York State to advance their technology and strengthen the state manufacturing industry. 

Incorporating UHPC into curtain wall design offers performance and sustainability benefits, including a far lower carbon footprint due to locally-sourced materials and low energy manufacturing processes, a longer lifespan, and long-term energy savings related to the building operations. These improvements are expected to yield significant advantages in future building costs and carbon emissions, and its fabrication by casting offers a nearly limitless diversity of architectural designs.

Metals in Construction sat down with Peter Arbour, a New York-based architect with 20 years of experience as a facade designer and consultant for projects worldwide, to learn more about the system’s development and the next steps in bringing the Liquid Wall to the New York construction market.

What kind of feedback have you gotten from New York City installation companies about the prototype? What are their questions?

The Liquid Wall is tailored to drop into our present-day unitized curtain wall installation methods using industry-standard equipment and skilled labor. Panels will be shipped to a construction site in crates, lifted to their designated floor slab in a freight hoist and installed with traditional slab-edge anchors. 

We’ve been working with a facade manufacturer that serves the Northeast construction markets, and they’re excited to have an innovative offering for their customers—a complete, prefabricated facade system with significant sustainability advantages and a cost of manufacture that can succeed in the competitive marketplace. 

I’ve received a lot of positive feedback from potential installers so far, some of which I attribute to the fact that we aren’t reinventing their process. We’re introducing a product that fits with current construction practices without increasing cost.  

For the facade installer, the Liquid Wall is an opportunity to get ahead of the pack.  Facade subcontractors are squeezed from all sides, and they face uncertainties that are tricky to manage and predict. A lot of our effort has been focused on designing our process with this reality in mind. Our business model depends on successful partnerships with installers. I’m actively seeking out good relationships with installation partners—relationships where we reinforce one another’s success. 

Everyone is challenged by the issues around climate change. The construction market’s demand for reducing carbon emissions, for both embodied carbon and building operations, will continue to grow. Regulation at city, state, and federal levels of government are creating changes in building practice. However, it has also become clear that sustainable construction is not the economic burden that many of us assumed it would be. The Liquid Wall makes the case that building sustainable buildings can be very good business. No business innovation is entirely risk-free, but rapid market changes call for innovation, and we are focused on producing a superior facade system at a competitive price.

Very soon we’ll be at a point where the demands of energy codes and carbon regulations go beyond what facade manufacturers can reliably provide. The 2024 International Energy Conservation Code (IECC) was published in August 2024, and Local Law 97 in New York City is reshaping expectations of building performance requirements. It’s not at all clear how traditional aluminum facade companies will be able to address these changes. So, to me, the answer is, let’s do something else. 

What stage of the product development and manufacturing process are you in?

Right now, we’re assembling a fully-engineered, performance mockup at Building Envelope Testing laboratory in Middletown, NY. We’ve been collaborating with the Rochester Institute of Technology for materials testing. We’re in the final stages of product development, incorporating lessons learned, and putting feedback loops in place for continuous product improvement. At the start of 2025, we’ll be fitting up tooling for the manufacture of a full-scale building performance mockup for final third-party lab testing and product certification.   

What questions are you trying to answer about the system currently? What would you like to tell architects about the system?

We are laser-focused on the evolving needs of today’s construction market. We have decades of experience with the traditional demands of high-performance, prefabricated curtain wall systems that include weather-tightness, structural movement, speed of installation and cost, among others. But the urgent need of the present-day market goes beyond these criteria. The Liquid Wall was developed as a solution to these well-understood problems and, at the same time, to address the rising demand in the market for reduction of carbon emissions that are causing climate change. 

By replacing aluminum with UHPC, the Liquid Wall performs 30% better thermally than an aluminum curtain wall. And in terms of embodied carbon, or the carbon footprint of the system, it creates 75% less embodied carbon than an aluminum curtain wall. So those are the things that I talk to a lot of people, including architects, about. 

It’s also designed for adaptability. It’s designed for glass replacement, and window replacement or upgrade from inside a building. Replacement of insulated glazing after less than 30 years is inevitable. With exterior glazing, this means slow, expensive, and dangerous capital projects performed from suspended scaffolding. It requires evacuation of leasable space, sidewalk bridges over public thoroughfares, and only kicks the problem down the road for another few years. Interior glazing is safe, rapid, and only requires you to move furniture. 

The UHPC material itself is incredibly durable: you could put it underwater in the ocean and it would last hundreds of years. So the idea is to create a permanent facade system, where all of the perishable components—insulated glass, spandrel panels, the gaskets and air seals, and everything else—can be replaced and upgraded over the lifetime of the building and into the very long future. 

On the design side, the wonderful thing for architects is that it’s a cast material. So it’s made in a mold, the mold can be any shape or form or texture that you can design. The base system is kind of a chassis, a frame. And there are performance components that are part of that: gasket rails that intermarry when you put the system on the building, mullions sized for structural performance, and all the parts and pieces that get cast into the concrete itself. That’s the minimum set of components you need; beyond that, it can be cast with sunshades, or it can be cast with images or textures or architectural features or ornamentation to suit the designer. It can be made in virtually any size, as well. 

Going back to something you said earlier, what is the weight comparison to a typical curtain wall panel? 

The design of the panel that we’re doing right now, the base design, is 5 feet wide and 12 feet high. That panel weighs under 2,000 pounds. So it’s comparable to a unitized curtain wall. It’s probably a couple hundred pounds heavier, but doesn’t require any more material in the primary structure of the building. Because of the nature of the UHPC, if you compare it to a precast concrete panel, it’s about 15% of the material. It’s a lightweight system that’s installed the way a traditional curtain wall gets installed and it doesn’t require heavier equipment than what installers are using now.

Can you talk more about how different aesthetic appearances can be achieved as well? 

A rendering of a Liquid Wall curtain wall concept.

In the Liquid Wall, UHPC is replacing the aluminum. In place of framing with extruded mullions and transoms, we cast a unit frame as a single piece. While the method of manufacture is quite different, the framing dimensions are roughly the same. The strength and composition of the UHPC material allows for very slender profiles as compared to reinforced concrete, and, by the casting process, we’re able to include opaque surface designs—texture, relief, 3D shapes, and veneer materials—as an integrated part of each fabricated panel. 

The Liquid Wall is, in some respects, like a hybrid of the unitized curtain wall we know— with factory-installed glass and windows, dry gasketing between panels and lightweight installation methods—and precast concrete facades—with their versatility of detail, surface material and color. We take the best of both worlds and combine them into a single system.  

The system can accommodate any kind of veneer. So, it can be done with brick face, terracotta, or stone. In each panel, we have vertical and horizontal profiles. Mullions of 8 inches by 2 inches form the perimeter of the panel. In opaque areas of the panel, the face is a half-inch thick UHPC, so we get 7 1/2 inches of clear depth for insulation. Where we have glass or an operable window, it’s an open picture frame. 

In the aluminum scenario, you have flat painted metal, extrusions, or coil. And with Liquid wall you have a 3-D option, so you can do stuff that’s a shallow or deep relief or a veneer. In a traditional facade system, you’d have to go to precast to do that, and suddenly the panels would weigh 10,000 pounds instead of 2,000 pounds, and the building’s structural design must accommodate that, which adds cost and carbon to the project.

A full-scale prototype of the Liquid Wall was exhibited at the Center for Architecture in 2010, after winning an open competition for curtain wall design. Can you talk about your personal motivation to keep working on this project over the course of 15 years?

The Liquid Wall prototype on display at the Center for Architecture in New York City in 2010.

Following the AIA competition award and exhibition, I was the Sales Manager for North America at seele, Inc. for several years and then Partner with Socotec US for several more. I had a fantastic journey of learning and applying my skills while working on dozens of great buildings with some of the best project teams in the business.  

Seeing the rapid change in our profession over time and the carbon-related challenges that builders face today, I recognized that the Liquid Wall is a powerful remedy to the pain points in the facade market.  About two years ago, I decided it was time for commercialization.  

I’ve been doing facade consulting and contracting for a long time, and I thrive on the collaboration of owners, architects, engineers, manufacturers, and contractors. What I enjoy most is having the many stakeholders in a room figuring out how to build something together—and not just build anything, but build something great. Something we can all be proud to invest in, to work on, to live in or even just pass on the street.  For the amount of effort, energy and capital that making a building requires, to me it only makes sense to aim high. So that’s my motivation. 

The Liquid Wall is a facade system engineered to make great buildings—sustainable, resilient, profitable and beautiful buildings. The paradigm for making great buildings has changed, and the mission of the Liquid Wall is to make the most of it. 

So, that’s what this work is about. And it’s about figuring out a way to enable designers, because I feel strongly that architecture and our built environment is in the strangle-hold of commodity industries. Too often, all you get to do is choose a color. Apart from the unsustainability of all-glass buildings, there’s little that relates to the scale of the people that are there. And yet that is the state of the art. 

It’s state-of-the art, but it still has such a limited lifespan, compared to something where you could replace components, and materials.

Totally. One of the more hopeful aspects of the conversation about climate change is where we start taking into account the long future and the overall lifecycle of buildings.  These things have real consequences, not only for the urban landscape and architecture and whatever else. The financial cost of replacing expensive facades in kind every 30 or 40 years quickly gets to the point where the state-of-the-art facade becomes a liability that’s worth more than the property asset it’s enclosing.

What will the FuzeHub grant allow you to do moving forward? 

Arbour, next to a test mockup of the Liquid Wall fabricated in January 2025.

The Fuzehub grant is an essential piece of the budget for full-scale mockup testing that will take us to the point of being ready for market. Coming through the certified lab testing with the industry standard test specifications is basically our product certification. That’s what we bring to the department of buildings and to architects and building owners for use in their project specs. In combination with other funding we’ve raised and been awarded, the grant will be used to certify the Liquid Wall as a product in the market.

Our beachhead market is New York; we’re based in New York and our manufacturing is in this region. Material supply is locally sourced so we’re in a good spot to begin here. There’s a big market here, and, specifically in New York City, regulation is driving demand for sustainable building and carbon emissions reduction. And from here, we can reach Boston and Washington and everywhere in between. Further growth will be into regional markets where the approach will be to establish local manufacturing. Industry partnerships will also be critical, not just on the installation side, but also on the manufacturing side.