Written By:
William Richards
We’ve come a long way since the architect Philip Johnson designed his iconic Glass House in New Canaan, Connecticut, which graced the covers of magazines 80 years ago and remains a touchstone of Modern architecture. But windows must do a lot more these days than offer a window onto the world. They’re critical components that influence a building’s performance, comfort, appearance, and long-term value. Whether you’re designing a residential home, a commercial office, or an institutional facility, specifying the right windows means making smart, well-rounded decisions that go beyond aesthetics.
Thankfully, there are trusted resources available to help navigate the complexity. The Window & Door Manufacturers Association (WDMA) provides detailed guidance through their Window, Entry Door, and Skylight Standards. (These standards offer a practical, industry-accepted reference for evaluating window performance across categories like structural integrity, air infiltration, thermal performance, and safety.)
“Energy Efficiency” Isn’t Just a Buzzword
It’s a foundational consideration in modern window selection. Windows significantly impact a building’s thermal performance, which in turn influences HVAC sizing, operating costs, and occupant comfort. Key metrics include U-factor, solar heat gain coefficient (SHGC), and visible transmittance (VT). Double- or triple-glazed units with Low-E coatings and gas fills (argon or krypton) can dramatically improve insulation. Thermally broken aluminum or composite frames further reduce energy loss, especially in extreme climates.
Projects like 10 Hudson Yards in New York, designed by Kohn Pedersen Fox (KPF), demonstrate how large commercial buildings can balance scale, aesthetics and energy performance. The tower’s curtain wall system—manufactured by Permasteelisa Group—includes high-performance glazing that manages solar exposure and meets rigorous LEED requirements.
For residential projects, energy efficiency is no less critical. NO ARCHITECTURE’s Flower House in Berkshire County, Massachusetts, for example, uses triple-glazed, thermally broken windows from Zola to ensure high thermal performance in a cold climate. The strategic window placement and high-performance envelope enable passive solar heating while reducing mechanical reliance. WDMA’s standards provide performance classifications and test protocols, allowing architects to specify products with confidence and compliance.
A Room with a View
Natural light and visual access to the outdoors are essential for well-being. Good daylighting design can reduce artificial lighting needs, boost occupant mood, and make spaces feel more expansive. When specifying windows, consider orientation, aperture size, head height, and glazing clarity. High-VT glazing improves daylight penetration, while thoughtful placement minimizes glare. In residential settings, operable clerestories or floor-to-ceiling units can distribute light deep into the plan.
The New Barn by RIOS in Santa Monica is a prime example. This coastal residence uses expansive glazing by Western Window Systems to erase the boundary between interior and garden. Large operable windows are oriented to pull in diffuse California light while maintaining privacy through screening and landscaping. (Similarly, at Flower House, NO ARCHITECTURE uses full-height windows that choreograph views to the natural landscape.)
Windows are not just functional—they’re spatial devices that enhance indoor-outdoor connectivity and emotional comfort. Operable windows provide natural ventilation, reduce cooling loads, and allow occupants to modulate indoor environments. In mixed-mode buildings, they work in tandem with mechanical systems for more sustainable air management.
Different window types offer different performance: casement, awning, and tilt-turn windows tend to seal tighter than sliders or double-hung units. Operability must be weighed against weather-tightness, energy goals, and user access.
At Flower House, NO ARCHITECTURE’s use of tilt-turn windows allows for versatile ventilation in a climate with wide temperature swings. Meanwhile, the Modern Barn leverages large pivoting and sliding units to bring in ocean breezes while maintaining a seamless aesthetic. WDMA’s performance standards for air infiltration and operational force can help ensure operable units perform well over time, particularly in demanding environments.
Details Matter
Windows are one of the most visually impactful components of a facade. Their size, shape, proportion, and detailing all influence architectural expression—whether you’re designing something sleek and modern or warm and traditional. Consider frame material and thickness, mullion profiles, and how hardware contributes to or detracts from the design intent. Align window heads and sills with other architectural features to create rhythm and coherence.
In commercial buildings like 10 Hudson Yards, the sheer scale of the glazing system is part of the architectural identity. In contrast, smaller projects like Modern Barn and Flower House demonstrate that even residential-scale windows can carry strong formal and spatial presence.
Selecting manufacturers that offer design flexibility and a variety of finish options—such as Western Window Systems, Zola, or Andersen Architectural Collection—can help you stay true to your design language without compromising on performance.
Durability is About Material Choices
Windows must withstand daily use and environmental exposure over decades. Material selection plays a major role here. Aluminum frames offer durability with minimal upkeep but can underperform thermally unless thermally broken. Wood brings character but requires protection or cladding. Fiberglass and composites are increasingly popular for their strength, low maintenance, and thermal resistance. For commercial or coastal buildings, corrosion resistance and impact-rated products are essential. In residential work, ease of cleaning and hardware longevity are major concerns.
WDMA standards include performance evaluations for air leakage, water penetration, and structural integrity—all helpful when comparing manufacturers and specifying windows that last.
Balancing Cost, Value, and Performance
Cost is often the balancing act between ideal and practical. While it’s tempting to default to low-cost solutions, total value—including energy savings, durability, and aesthetics—should drive decision-making. Prefabricated units may reduce installation time. Thermally broken, high-performance windows cost more upfront but often pay for themselves in energy savings. And standard sizing can help manage budgets without compromising design if used thoughtfully.
Working with manufacturers early can help architects explore performance-based substitutions or alternate materials without diminishing design integrity. Safety requirements vary by code and context but are non-negotiable. This includes tempered or laminated glass in areas prone to human impact, egress requirements in bedrooms, and fall protection for operable windows above certain heights.
In commercial and high-rise buildings, wind-load resistance, blast mitigation, and even bird-safe glazing may come into play. Coastal zones often require impact-rated windows that meet Miami-Dade or ASTM standards. Manufacturers like Viracon and Guardian Glass offer specialized glazing for high-performance and code-compliant applications, from thermal performance to safety glass.
What’s the upshot? Specifying windows is more than selecting a product—it’s a matter of integrating performance, aesthetics, and long-term usability into a single decision. Projects like 10 Hudson Yards, Flower House, and Modern Barn show us that when done thoughtfully, windows don’t just serve a function—they enhance the life and identity of a building.
For architects who want to work smarter, not harder, the WDMA Window, Entry Door, and Skylight Standards offer a reliable, performance-based foundation for confident, informed specification. When you match technical standards with creative vision, windows become powerful tools for better buildings—and better experiences.
William Richards is a writer based in Washington, D.C., and Paris and the co-founder of Team Three, an editorial and creative consultancy.
Webinar: Understanding Window, Door & Skylight Certification
Understand the benefits of window, door and skylight certification and how certified products can enhance your projects.
Webinar: Understanding Window, Door & Skylight Certification
The Understanding Window, Door & Skylight Certification webinar is designed to help architects and remodelers understand the benefits of window, door and skylight certification and how certified products can enhance their projects.
