Glazing for sustainable buildings

Glazing, which refers to the use of glass or other transparent materials in building envelopes, can contribute to building sustainability in several ways, such as energy efficiency, passive heat gain, shading techniques, controlling window to floor ratio, thermal insulation, thermal comfort, managing air infiltration and opening mechanisms, internal air quality, controlling daylight flux, allowing visual connection with the surrounding environment, psychological comfort, UV protection, Photo Voltaic integrated within the glass for electricity production, sound insulation, building aesthetics, among other factors.

As for energy efficiency, high-performance glazing systems can significantly improve a building's energy efficiency. For example, by incorporating low-emissivity coating, multiple glazing layers (usually two or three), and inserting thermal insulating materials between glass layers such as stable or noble gases, for example Freon and krypton. These methods of glazing, including creating a void between glass layers by creating negative pressure, can reduce heat transfer in both directions, and enhance thermal and sound insulation. This helps in maintaining comfortable indoor temperatures and reduces reliance on heating, ventilation, and air conditioning systems, thus lowering energy consumption and the associated greenhouse gas emissions, as well as facilitating thermal comfort.

Glazing also allows natural day light to penetrate the building envelope, reducing the need for artificial lighting during daylight hours. By optimising window placement, shape, size, and glazing properties, it is possible to maximise daylight penetration while minimising glare and excessive solar heat gain depending on the angle of the sun during all seasons. To insure this outcome windows shape, placement and ratio on particular elevations and shading techniques are important. This improves occupant thermal comfort, reduces energy consumption for lighting, heating and cooling and enhances the overall visual appeal of the space.

Glazing can be strategically designed to allow solar radiation to enter the building, where the glazing can help harness solar energy efficiently, capturing and storing heat energy in winter. This is particularly beneficial in colder climates, including the Mediterranean conditions, as the case in Jordan, where passive solar heating can reduce the reliance on heating systems in winter. This can be achieved through incorporating features like south-facing windows, designing the longer elevation of the building to face south and providing thermal mass materials along the building envelope, such as hollow concrete blocks in internal walls and solid tiles on the floors, rather than using wood and other light materials. The thermal mass on the internal faces of exterior walls reduces the overheating effect in summer as a result of applying intensive thermal insulation.

Biophilic design of exterior openings, which gives access to views and connection with the natural environment, has been shown to have positive impacts on building occupant`s well-being, mood, vibe and productivity, evoking positive emotions, and reducing stress. Biophilic design is an approach that recognises and embraces the innate human tendency to seek connections with nature and natural environments. Glazing provides opportunities to create panoramic views and establishes a visual connection with the surroundings. Incorporating biophilic design principles, such as incorporating natural elements and patterns, for example the use of plants, water features and natural materials, that aim to create spaces which are visually appealing, psychologically supportive, and conducive to human well-being, can further enhance the benefits of glazing by fostering a sense of well-being and connection with nature. This is well represented in the well-known Damascus courtyard in the Levant region in general.

To avoid resorting to big glazing surface areas, biophilic design often incorporates natural patterns and materials with the right colours that mimic those found in nature. This can be achieved through the use of textured glass, patterns inspired by natural forms, or the inclusion of natural materials like wood or stone in the internal glazing design. This can be incorporated within an enclosed area inside the premises. Other natural elements, such as indoor plants, green walls or water features can be improvised near the glazed areas for the same purpose.

Glass is a highly recyclable material, and properly designed glazing systems can be disassembled and recycled at the end of their lifespan to manufacture new glass elements rather than ending up in overloaded landfills. This recycling process helps reduce waste and minimise the environmental impact associated with glass disposal, as well as increases building sustainability and creates a boast for circular and green economies. Additionally, using durable glazing materials, such as Polycarbonate which is a lightweight and shatter-resistant glazing material, is highly durable and can withstand impact, making it suitable for applications wherever safety is a concern, such as skylights and security windows. It requires minimal maintenance and has a longer service life, reducing cracks, wear and tear and scratches and thus reduces the need for replacements. This, in turn, reduces the demand for new glass production and lowers the associated natural resource consumption as well as energy and manpower requirements.

Glazing systems can also provide effective sound insulation, reducing noise pollution from external sources. This is particularly important in urban areas or buildings located near high-traffic zones. Improved acoustic comfort can contribute to occupants satisfaction, their health and well-being. If there are specific concerns about the proximity of a building to high power electricity lines and their potential health impacts, specialised glazing products known as "electromagnetic shielding glass" or "EMF shielding glass" can be considered. These types of glass are designed to reduce the transmission of electromagnetic radiation, including the frequencies emitted by power lines. They incorporate metallic coatings or films that help reflect or absorb the EMFs, thus reducing their penetration into the building.

In conclusion, to maximise the sustainability benefits of glazing in buildings, it is important to consider factors such as orientation, shading, thermal performance, building materials of thermal mass, glass various qualities, local climatic conditions and overall building design. Proper thermal and acoustic installation, mechanisms of openings, choosing the required glass property, maintenance and glazing to area ratio are also essential to ensure optimal performance, sustainability and energy efficiency over time, particularly in our warming world.