As temperatures rise and hot spells increase, exterior sun shading is becoming an indispensable passive measure to combat climate change. It is clear that it will become ever more challenging to maintain pleasant temperatures inside buildings and keep users comfortable – particularly if air conditioning is not to be used. Air conditioning systems use a lot of energy and cause further CO ₂ emissions. In addition, their thermal discharge increases the microclimate in urban spaces, intensifying the rise in temperatures.

If air conditioning is required in a building, sun shading can help to reduce the cooling load, meaning that less energy is used and less CO ₂ is emitted.
“The automation of sun shading, in particular, guarantees an optimal result,” emphasises Markus Schwab. A building physicist at Warema, Schwab advises architects and specialist planners on the potential to save energy and CO ₂ with sun shading systems. “Users often wait until it’s too late to turn on the sun shading, doing nothing until the room has become noticeably hotter. What’s more, an automated sun shading system will respond even when the user isn’t there”, Schwab continues.

Even in buildings without air conditioning, sun shading systems can benefit energy usage and user comfort: in summer, they prevent sunlight from entering a room directly, significantly reducing the incidence of energy. The temperature in the room remains pleasantly cool. On cold winter nights, closed roller shutters, for example, can also save on energy and therefore CO ₂ . An air pocket forms between the window and the shutter, reducing the heat transmission coefficient and helping to keep the heat inside the building. Furthermore, the incidence of energy from the sunlight can be used during the day while protecting against glare. Automated sun shading can reduce the energy required for heating by up to 30% (Hauser study on behalf of IVRSA).

Comparing potential CO ₂ savings with emissions
This means that, during their service life, sun shading products can save on CO ₂ emissions. But greenhouse gases also come into play during raw material extraction, production, logistics, product use and product disposal. To clarify the balance between potential savings and emissions, Warema has analysed the carbon footprint of its three most popular sun shading solutions: the external venetian blind window system, the front-mounted roller shutter and the front-mounted awning. The analysis considers the entire product-related value chain from raw material extraction to product disposal.

The calculations are based on the internationally recognised Greenhouse Gas Protocol. All three scopes have been analysed – direct and indirect emissions at the production location and indirect emissions along the value chain.

A medium-sized, commercially available variant was used for each of the three sun shading solutions. The potential CO ₂ saving was calculated based on a room in a non-residential building (LxDxH 8.25 m x 5.4 m x 2.8 m) with a window surface area of 70 percent (16.17 m ² ) on the western side. Active cooling was set at 22°C. A service life of 20 years (or 10,000 load changes) was assumed. The calculations were performed using a tool from Repräsentanz Transparente Gebäudehülle (RTG).

A clear case for sun shading
The results showed that the CO ₂ emissions of the sun shading products are between 265 and 293 kg CO ₂ equivalent (CO ₂ e). The window awning had the lowest emissions, the roller shutter the highest. In all cases, the additional raw materials purchased made up the lion’s share of the total emissions – between 82.4 and 90.6 percent. It is striking that the energy and maintenance required by motorised solutions have very little impact on emissions.

In contrast, potential savings during a product’s service life are up to 28 times higher than its CO ₂ emissions. A window awning can save up to 7297 kg CO ₂ e in the conditions previously described, an external venetian blind up to 5834 kg CO ₂ e and a roller shutter up to 3931 kg CO ₂ e. Even with a roller shutter, the potential CO ₂ savings are 13 times higher than the CO ₂ emitted during the product’s entire lifecycle.

With these clear figures, the analysis once again underlines the importance of exterior sun shading for climate-resilient construction – both in new builds and when renovating existing buildings. Every building has its own particularities and must therefore be considered as an individual case. Warema has therefore made specially trained consultants and building physicists available to assist architects and specialist planners: https://architects.warema.com/en/ .

Group-wide climate strategy
Analysing carbon footprints at product level is part of Warema’s group-wide climate strategy. The carbon footprint of the Warema Group was first calculated at 260,000 t CO ₂ e for the base year of 2021 in accordance with the Greenhouse Gas Protocol. In the first subsequent year, Warema managed to reduce its footprint by around 11 percent to 232,000 t CO ₂ e solely through reduction measures such as increasing energy efficiency and using renewable energies. Warema has ruled out the possibility of compensation measures. Since the start of 2023, it has also been involved with Science Based Targets, a climate protection organisation.

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