ConverLight® – Tested, Documented & Proven in Real-World Studies

The EU-funded Switch2Save project aimed to explore and develop new solutions for more energy-efficient buildings, specifically focusing on how dynamic sunshade technology affects a building’s energy consumption. As the leading European researcher and developer of dynamic glass, the Swedish ChromoGenics system ConverLight® Dynamic was chosen as a benchmark.

Two buildings were selected: a hospital in Greece and an office building in Sweden. A comparative two-year study was conducted to analyse energy consumption before and after the installation of ChromoGenics’ ConverLight® Dynamic glass. In parallel, researchers at the National Technical University of Athens in Greece and the German Fraunhofer Institute also carried out detailed simulations using the same system.

Large glass facades significantly impact a building’s energy efficiency. In winter, buildings with a high ratio of windows to walls (WWR) can have up to 35% higher heating demands. In summer, the need for cooling can increase up to five times as WWR rises from 10% to 90%.

Two main factors determine a window’s energy efficiency. The first is the insulating properties (U-value) of the insulated glass unit (IGU), where the latest glass technology can provide the same insulation properties as an insulated brick wall. The second is heat and light transmittance (g-value), which is more challenging and complex to control as solar exposure greatly varies depending on the season, time of day, and geographic location.

Non-residential buildings, which often use large glass areas for functional and aesthetic reasons, are particularly affected by this. To address these challenges, electrochromic (EC) technologies like ConverLight® adjust and reduce heating demands in winter and cooling needs in summer.

Sweden’s largest property owner Vasakronan, praised for their sustainability work, offered their office building Sleipner in Uppsala, as a testing ground for this study. After a year of data collection, the conventional glass* was replaced with over 50 new ConverLight® Dynamic windows, covering 200 square meters. The results were remarkable. In March 2023 alone, energy consumption for cooling decreased by a staggering 80% compared to the previous year with the conventional setup.

Peak activity, and therefore electricity use, in office buildings typically occurs during the middle of the day, when sunlight is at its brightest and the demand for cooling is highest. This is also when electricity prices tend to peak, so reducing the need for cooling during this period can quickly become profitable for property owners. Additionally, lowering the cooling demand at midday typically reduces a building’s peak electricity and heat load, allowing for the downsizing of both HVAC and electrical systems. In some cases, the need for air conditioning can be eliminated. This provides substantial cost savings and enhances the overall energy efficiency of the building’s HVAC system.

*Before switching to dynamic glass, the building was equipped with a traditional external sun shading solution. Due to the substantial reductions in energy consumption for cooling, it is assumed that the traditional awnings did not function properly. Wear, tear and high maintenance requirements are known challenges with traditional solar control systems.

The General State Hospital of Nikaia, one of the major healthcare institutions in Athens, Greece, faces extreme heat during the summer. Maintaining a comfortable indoor climate is therefore crucial for the well-being and recovery of its patients and staff.

As part of the EU-funded Switch2Save project, ConverLight Dynamic was installed on the top floor of the hospital, which was particularly exposed to the sun and known for significant cooling challenges. The goal was to extreme-test its ability to improve thermal comfort while reducing energy consumption.

Compared to days with similar weather conditions, rooms equipped with ConverLight immediately saw an impressive 8°C reduction in indoor temperature. Cooling needs were reduced by 28%, significantly lowering energy costs. As a positive bonus, hospital staff also reported improved patient recovery (children) thanks to the optimised indoor environment. Both hospital representatives and EU assessors were extremely pleased with the result of the trial, further confirming the potential for ConverLight to revolutionise climate control in healthcare facilities.

Scientists at the Spanish research organisation Leitat received samples from ConverLight® Dynamic to perform real-life tests on performance and energy simulations in a controlled environment. The simulations and tests focused on three key criteria:

• Minimising overall annual energy consumption.
• Maintaining visual comfort with indoor illuminance between 300 lux and 3000 lux.
• Ensuring thermal comfort by keeping indoor temperatures between 20°C and 26°C.

Energy performance simulations conducted across various European climates demonstrated that ConverLight® reduced annual energy consumption for heating, cooling, and artificial lighting by 25-35%. This represents a significant improvement compared to the best static solar control glazing on the market. The real-world measurements from the ConverLight® installation in the Sleipner building exceeded simulation predictions. However, the actual results will depend on factors such as the condition, location, and specific characteristics of each building and can be calculated for a specific building using building physics software such as IDA ICE.

The ConverLight® technology also demonstrated a remarkable ability to adjust light transmission, ranging from 14% to 71%. This wide range of modulation ensures optimal light control in various conditions, enhancing both comfort and energy efficiency.

These results highlight the potential of Chromogenics ConverLight® Dynamic to significantly enhance energy efficiency and indoor comfort in buildings, making it a leading solution in smart glazing technology.