Published by: | Jennifer Geleff | Aug. 31, 2017

lass block is back and beautiful as ever. However, given today’s climate, it is important that in celebrating its resurgence, we simultaneously investigate its potential as an environmentally sustainable material choice. Remember, beauty is nothing without brains. Fortunately, glass block and its dynamic relationship with light gives architects the opportunity to create both aesthetically pleasing and energy-efficient spaces.

This article will investigate avenues of achieving certification under the newest LEED v4 Building Design and Construction rating system, specifically when building with glass block. Beyond the street credibility associated with certification, you will be working toward ensuring that your design is committed to improved energy performance and energy-saving strategies and, in turn, meets the international standard for the design, construction and operation of high-performance structures.

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Infographic via Miami Urban Green (click to expand).

LEED, or Leadership in Energy and Environmental Design, is the most widely used third-party verification tool used to classify green buildings. Projects pursuing LEED certification earn points across several areas that address sustainability issues, and based on the number of points achieved, a building receives one of four LEED rating levels: Certified, Silver, Gold and Platinum. Think of points as the foundation of your building; you can’t build up without them in mind.

It is essential to identify how you will go about earning points and thus pursue accreditation. When using glass block, your selection will be centered on the material’s heat insulation, controllable transmission of light and the fact that it is a durable, completely recyclable and renewable material affecting the building’s overall life cycle. Luckily, today’s LEED Certification guidelines consider the interior wellness conditions of a building to be critically important.

For example, the Daylight criteria rewards buildings that seek to connect occupants with the outdoors, reinforce circadian rhythms and reduce the use of electrical lighting by introducing daylight into the space; a category you will definitely want to home in on when designing your next glass-block building.

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Here are some of the LEED categories in which you may choose to earn your points: Optimize Energy Performance, Building Life-Cycle Impact Reduction, Building Product Disclosure and Optimization – Source of Raw Materials, Building Product Disclosure and Optimization – Environmental Product Declarations, Building Product Disclosure and Optimization – Material Ingredients, Low-Emitting Materials, Interior Lighting and Daylight. All of these categories may be found in the LEED credit library.

Once you have solidified your approach for achieving LEED certification, you must choose the right glass block for your project. There are quite a few considerations that you will need to parse out.

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Left: Seves Fire Resistance glass block; . Right: Seves Privacy glass block;

Depending on the pattern of glass block that you select, light transmission can range from that of a traditional window pane to a range of increasing degrees of blockage. Glass blocks with a clear smooth face offer high levels of light transmission and visibility. Wavy and fluted patterns maintain high levels of light transmission while allowing for moderate levels of visual privacy. Even greater blockage comes with stippled, diamond and tightly ribbed designs such as Seves’ Privacy glass block pictured above. In choosing the right product, it is essential to think about the interior light conditions you are hoping to achieve.

When considering the heat insulation capacity of a particular glass block, look for its U-value in the product’s specification sheet. Measured in Watts per square meter Kelvin, a lower value is better; it indicates that less heat is lost or gained. Seves’ Energy Saving glass block reduces the thermal transmittance of the material up to 50 percent, making it possible to create entire architectural façades that promote the conservation of energy. The model introduces a low-emissivity glass plate in the center of the block, which interrupts the thermal bridge.

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The façade of the Grupo Precisión Building by Guillermo Acuña Arquitectos Asociados features Seves’ Energy Saving glass block, which renders favorable interior light conditions; via ArchDaily.

A final consideration is the louvering effect of the mortar joints between each glass block. Because glass block is nonporous and, therefore, does not absorb any moisture, the mortar used to install a wall of glass blocks must be stiffer than the typically wetter mortar used for other masonry products; it should be similar to the consistency of peanut butter. This thick gooey mortar helps reduce light transmission by interrupting and redirecting sunlight. Smaller blocks mean more louver joints and thus an increased shading effect.

If the aforementioned approaches are not dramatic enough, the forward-looking reliable minds of science have got you covered. In order to leverage glass blocks to accelerate the widespread introduction of net-zero energy buildings, researchers are also looking toward the latest in Building Integrated Photovoltaics. Manufacturers like Seves Glass Block already market Photovoltaic glass blocks, which capture sunlight during the day in order to power LED bulbs at night. However, even more exciting research is rumbling afoot.

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Left: Seves’ Photovoltaic glass block captures daylight in order to power LED bulbs at night, image via Seves Glass Block; right: with Solar Squared, glass blocks could convert the sun’s energy into electricity; via University of Exeter.

Renewable energy experts at the University of Exeter in England invented a glass block with performance factors that resemble Tesla’s solar tiles. Called Solar Squared, the attractive modular blocks are designed to seamlessly fit into new constructions and renovations in hope of replacing traditional bricks and mortar with transparent glass. Each block has intelligent optics that focus the incoming solar radiation onto a small solar cell, which will then be able to power the building, be stored or used to charge electric vehicles. After years of research into integrated solar technologies, the team created Build Solar: a spin-out company dedicated to further developing and innovating.

Glass block is a perfect example of the many ways you may manipulate a single building-product in order to achieve your ideal building results. And with the committed work of innovative manufacturers and researchers like Seves Glass Block and Build Solar, glass block can and should play a leading role in the future of green construction. While LEED-certified glass-block building precedents remain few and far between, the time to shake things up is now. Are you building with glass block and aiming to achieve LEED certification? We’d love to hear from you!