To glass or not to glass, that is the question. In an era where environmentalism is a top priority, some say that glass heavy buildings are a broken model while others work to make windows more eco-friendly and safe. As manufacturers and architects slowly but steadily improve window technologies, the debate persists.
In Defense of Windows
The giant, glass-faced skyscraper has long been a symbol of prestige and can oft be found on postcards celebrating the skylines they comprise. Buildings large and small use windows to allow sunlight, facilitate views, and create the impression of openness and increased room size. Windows are even linked to psychological wellness and increased community engagement. They’re popular design elements for good reason.
Environmental Impact of Windows
Windows are not without their shortcomings, however. They are notorious for allowing cold or hot air into buildings, making temperature regulation a challenge and running counter to energy saving efforts. As such they are considered ‘thermal bridges’ and poor insulators. If that’s not enough, the glass itself is high in embodied carbon.
“Glass buildings are inappropriate responses to the climate emergency in which we live,” Monte Paulsen, a Passive House specialist at RDH Building Science, in Burnaby, B.C. tells Corporate Knights. “There is currently no way to construct a glass box that will achieve a high level of thermal performance. Glass boxes are unique in that they perform terribly year-round. These are facts of physics.”1
Environmental Advancements in Windows
Armchair philosophers and journalists with writer’s block take comfort: staring out the window may not be destined to go the way of the dinosaur. For that we can thank innovators looking for solutions to the glass challenge.
‘Solar Glass Could Convert the Windows of Every Building Into Power-Generating Panels’ screams a headline from Forbes.2 The organic cell technology touted in the article remains expensive and limited in effectiveness, but is likely to improve on both fronts.
Another increasingly popular option is electrochromic glass. The so-called ‘smart glass’ changes its opacity in response to varying levels of light and heat, delivering energy efficiency as well as convenience.1
B.C.’s Cascadia Windows are producing triple pane windows filled with argon gas that doubles the R-value (a measure of insulation effectiveness) as compared to standard double-paned glass,.1
Calgary’s GlasCurtain is replacing traditional aluminum frames with extruded fibreglass frames, not only reducing the level of embodied carbon, but combating leaks and excessive condensation as well. The frames are not a silver bullet, but are Passive-House certified, allowing them to be used in low- or net-zero-energy projects.1
Advancements in Glass Safety
In addition to green efforts, design and manufacturing innovations are constantly seeking to improve the safety of glass. Among their aims are increased protection from burglars, fire and storm resistance, and the minimization of flying glass during an explosion.
As Julia Schimmelpennigh, a technical leader and support lab manager at Eastman Chemical Co. explains to US Glass Mag, glass safety has gone from afterthought to forethought.3
“Previously, only blatantly high-risk applications would have had security glazing specified at the design stage of a facility,” she says. “Today, more facilities are considering the early integration of these levels of basic protection to avoid costly retrofitting or occupational use limitations throughout the life of the building.”3
“New combinations of glass, interlayer and films, as well as formulation changes and adjustments in the polymer-based components, have been seen throughout the last 20 years,” she continues. “The use of multi-layer interlayers, for one has opened possibilities of bringing safety and security, but also continuing to deliver sound control, structural capacity, solar performance and lively color options.”3
Technology and Glass Architecture
Not surprisingly, technology such as simulators and computational design are being used during the design stage to measure the effectiveness of windows in heating, energy efficiency, and safety.
Simulation software tools such as Solemma’s Climate Studio uses a host of variables to measure various designs, producing an array of key performance indicators.4
“The resulting simulation software (solemma.com/ClimateStudio.html) can relatively quickly determine annual illuminance, glare, and thermal comfort distributions in building spaces designed for using daylight and artificial illumination,” says BDCNetwork.4 The software can be used within the certification process, and to test and archive various design ideas.
The safety applications of advanced software are equally important.
“Finite element analysis has become important when determining how materials and the façade system will react to the stress of a blast event,” explains Building Envelope Solutions VP Jeff Heymann. “Shock tube testing is sometimes used to replicate and direct blast waves at a building model to simulate actual explosions and affects. Finally there are a few facilities where full-size mock-ups similar to performance mock-ups are installed and tested with live explosives.”5
Even as building regulations tighten, the traditional appeal of glass will remain. Innovative researchers and engineers will need to answer the challenge if we are to continue enjoying the benefits provided by window-centric design.
