Sustainable glass façades

Print 22 Nov 2019

Sustainable glass façades – a key factor in circular construction 

Sustainability has gone from being a trend to a golden rule for living on our planet. It’s about living in ways that enable us to obtain what we need without harming others or the natural environment. Contributing to sustainable development is about meeting our current needs without preventing future generations from getting their needs met. Today’s construction industry is responsible for a large share of global emissions as well as energy and resource consumption. It goes without saying that actions in this area have a crucial bearing on the environment. For this reason, various standards have been established for evaluating construction sustainability based on Life Cycle Assessment (LCA). [1]

A building’s carbon footprint is evaluated on the basis of lifecycle assessments, which consider the building’s entire lifecycle from raw material production and construction, through operation and maintenance, to demolition, recycling and end-of-life waste management. Environmental Product Declarations (EPDs) are used to document the environmental profile of the building components. This includes glass façades.

Sustainable glass and aluminium façades
Much has changed in the last 60 to 70 years since aluminium began being used in façades. The biggest change lies in improved insulation capacity through the use of thermal breaks in aluminium profiles and high-insulating glass. Today profiles are available that perform to passive house standard (U value of 0.8), while glass is reaching ever lower values, which can be below 0.5 W/m2K. This reduces heat loss and minimises the amount of energy needed to heat the building. By integrating more technology into façades, such as automated blinds, screens and electrochromic glass, buildings can be made to react to external factors and the indoor climate can be improved by preventing glare and reducing the need for cooling. Aluminium glass façades have a long lifespan and do not degrade over time. Moreover, their maintenance requires less energy and generates lower carbon emissions. Aluminium is highly weather-resistant and improves the façade’s quality and solidity.

While a tight façade helps minimise energy costs, the glass’s ability to let in natural light and provide external views are crucial factors for the health and wellbeing of the people in the building. Glass façades create a feeling of openness. This is essential for people today, most of whom spend more than 90% of their time indoors. In the report “10 kvalitetsprinsipper for bærekraftige bygg og områder” (10 quality principles for sustainable buildings and areas) carried out by Bygg21 for the Ministry of Local Government and Modernisation in 2018, one of the ten principles regards the importance of access to natural light and external views, which promotes health, wellbeing, learning and productivity. Good light conditions are based on an interplay between daylight and artificial light. Restricted and inadequate access to natural light can negatively impact the health of building occupants. Moreover, there is a difference between external view and external visibility. Having an external view means being able to look out from a building or a closed area and get an overview of one’s surroundings. A building that provides a view of vegetation, nature or green areas is better for people’s health than one that doesn’t. It used to be dangerous to create large openings in a building façade using glass and aluminium. Aluminium profiles today have a higher weight bearing capacity, which allows larger glass panels and glass expanses to be used in façades.

Aluminium as a green material
Demand for aluminium is rising faster than for any other metal in the world. This is primarily due to its low weight and high strength. The demand is, in particular, driven by the transport sector’s need to increase fuel efficiency and reduce energy consumption with lighter cars, trains and trucks. Moreover, aluminium is the key to zero-energy buildings, solar applications and packaging that preserves food and reduces transport energy use. Aluminium is low-maintenance, does not corrode under normal conditions and has a long lifespan.

Aluminium alloy and environmentally friendly production
An aluminium alloy is a mixture of aluminium and one or more other metals. Hydro produces alloys to improve material properties for specific purposes, for instance strength, sheen or malleability. The most common alloying elements used in aluminium alloys are magnesium, silicon, manganese, zinc and copper. Profiles for windows, doors and façades are produced by heating an aluminium bar to 500°C and pressing it through a die with the same shape as the finished profile. With the right alloy and correct heat treatment, profiles can be produced for countless applications. [2]

There are few metals with a lifecycle like aluminium. Aluminium is corrosion-resistant and can be recycled again and again, which requires just a fraction of the energy needed to produce primary aluminium. This is what makes aluminium such an outstanding building material. Approximately 75% of all aluminium ever produced is still in use. A lot of energy is required to create primary aluminium, but Hydro uses renewable energy and modern technology to produce aluminium in the cleanest way possible. In 1963, Sapa’s parent company Hydro opened its first aluminium production plant based on hydropower on the island of Karmøy in Rogaland, Norway. This marked the start of Hydro’s journey to becoming the world’s leading producer of sustainable aluminium. Today the company operates more than 20 hydropower facilities throughout Norway. These facilities provide around 10 TWh of clean and renewable energy annually for Hydro’s aluminium production.[3]

Sustainable glass façades with 75% recycled post-consumer scrap
Demand for recycled aluminium in building materials has increased in pace with growing awareness of sustainability and the environmental footprint of buildings. Hydro is the first aluminium producer to supply prime quality recycled aluminium with a certified content of at least 75% recycled post-consumer scrap, through the Hydro CIRCAL product range. Hydro’s carbon footprint is 75% lower than average primary aluminium in Europe and nearly 90% lower than the global average. Operating the most advanced sorting technology in the industry allows Hydro to provide the highest recycled content in the market. The remelting of aluminium for new applications requires only 5% of the energy used to produce primary aluminium. The higher the recycled content, the lower the carbon footprint. This production process is fully traceable, and the product is certified by an independent third party (DNV GL).  

From 1 December, Sapa will be able to offer the market its glass façade Sapa 4150 with Hydro Circal 75R and help reduce the carbon footprint of buildings worldwide.

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