Balancing energy-efficiency and aesthetics: Large-scale Thermal Fenestration Systems

The total energy demand from buildings has risen dramatically in recent years. Driven by improved access in developing countries, greater ownership of energy-consuming devices and increasing urban densities, today it accounts for over one-third of global energy consumption and nearly 15% of direct CO2 emissions. As the climate crisis aggravates and its consequences are more visible than ever, the architecture and construction industry must respond accordingly. It must take responsibility for its environmental impact and give priority to reducing energy consumption, whether through design decisions, construction techniques or innovative products. The key lies, however, in not sacrificing aesthetics and comfort in the process.

The main areas of energy use in a building correspond to heating, ventilation and air conditioning, meaning that the role of building envelopes and fenestration is pivotal. Of course, windows and doors are essential for natural light, views, air flow and entries. With the right systems and materials, they can also provide insulation for improved temperature control, creating a barrier against cold weather during winter and blocking outdoor heat during summer months. In this way, energy-efficient thermal fenestration systems can open many possibilities in the path towards efficient, cost-effective spaces – although they have higher initial costs, these are offset in a few years thanks to substantial energy savings.


One Hundred Residential Tower. Image © Tom Harris


Optimal thermal performance and appealing visuals

Often, the Passive House Certification is set as the leading standard in ensuring resiliency in buildings. Projects designed according to its criteria perform 60-85% better on an energy consumption basis when compared to code compliant projects. But in many large-scale buildings with complex configurations, like multi-family housing projects, meeting this standard can be quite the challenge. And if we add to this the desire to create spaces that are appealing to live or work in, it is clear that design professionals face a complicated task.



Vagelos Education Center. Image © John Muggenborg


Recognizing these needs, manufacturers of large format fenestration have focused on offering products that can be easily incorporated into a variety of building schemes. To be effective, these must follow a set of requirements: the glass selected in multi-pane units should restrict thermal heat flow or solar heat gain based on the building’s climate zone, the frames must be designed to control heat flow and thermal bridging within them, and the whole assembly needs to open easily to provide ventilation, yet still be able to close tightly to restrict unwanted air infiltration. All of this while responding to today’s visual demands, including expansive views, a connection to the surrounding landscape and a sleek, clean line contemporary style.

Recent innovations in engineering and design have taken these criteria into account to produce some appealing and efficient choices. For instance, CRL – the industry’s leading manufacturer and supplier of architectural glazing systems – has developed a series of large-scale fenestration products with a high thermal performance and outstanding functional (and aesthetic) qualities. We present some of them below, exploring their unique characteristics.


Sliding doors

Although oversized glass doors create striking visuals, they can also cause excessive heat loss or solar gain. With this in mind, CRL’s large-format sliding door systems provide daylight, uninterrupted views and maximum transparency while mitigating heat transfer using thermal breaks and insulating glass. Working with the rest of the building envelope to maintain comfortable interior temperatures, they place less strain on heating or cooling systems and foster user well-being. For example, the Palisades S100 Sliding Door, known for its elegant minimalistic look, is designed with ultra-slim panel rails and stiles, with panel heights up to 13 feet (approximately 3960 mm) and widths up to 7 feet (approximately 2130 mm). It features specialized seals designed to resist the entrance of air and water and is suitable for exterior applications with high loads, limits on deflection and heavy usage, exceeding in structural and thermal performance.


Palisades S100 Sliding Doors. Image Courtesy of CRL


Bi-folding doors

Characterized by multiple hinged panels that stack to one side, the latest bi-folding glass door systems also offer advancements regarding thermal and aesthetic qualities. When opened, they provide seamless transitions that allow for ventilation and daylight; when closed, they deliver a streamlined look, prevent obstruction to preserve views, and seal up tightly to protect against water and air infiltration. In addition, these can feature thermally broken frames and 1-inch (2.5 cm) double pane insulating glass that together produce standard U-factors of 0.36, maintaining comfortable interior temperatures year-round and putting less strain on air conditioning systems. This applies to products like the Monterey S80 and the Palisades S90, which are able to meet the aesthetic and functional needs of today’s buildings with their sleek appearance, smooth movement and ability to reduce heat transfer.


Palisades S90 Bi-Folding Door. Image Courtesy of CRL


Entrance doors

Entrance doors, for their part, can defy efficiency through air leaks – especially in large-scale buildings with constant circulation. In this sense, the Blumcraft Entice Series Doors were created to fulfill energy conservation requirements and simultaneously maintain an elegant appearance. The system has very slender vertical lines and the unique ability to support handle hardware on insulating glass with a “floating on air” aspect. It has also been engineered with thermally broken framing and cladding that lets the product achieve U-factors as low as 0.33. Altogether, Entice® enables architects to achieve an all-glass style while meeting increasingly stringent energy codes.


Blumcraft Entice Series Doors. Image © Trent Bell


To develop complex buildings or multi-family projects that are healthy, appealing and achieve high levels of energy-saving performance, architects must adopt a series of strategies. This includes design decisions like enhancing the building envelope with the proper use of Weather-Resistant Barriers (WRBs) and incorporating effective Variable Refrigerant Flow (VRF) systems. Fenestration, on the other hand, can be addressed by selecting large-scale doors that provide high thermal performance without compromising comfort and beautiful visuals. If these strategies are combined, it is possible to contribute to the universal goal of net-zero architecture, promoting human and environmental well-being.



Source Arch Daily

August 15, 2022