Switch2save · Project

Smart Glass That Cuts Heating and Cooling Costs in Large Commercial Buildings

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Imagine sunglasses that automatically darken when it's bright and lighten when it's cloudy — now put that technology into the windows of an entire office building. Switch2save combined two types of self-tinting materials into one lightweight glass unit that blocks heat in summer and lets warmth in during winter. They tested it by replacing over 50 windows in a Greek hospital and a Swedish office building, then measured the energy savings for a full year. The goal is glass that's 20% better than current smart shading and 33% cheaper to make.

By the numbers

25–60%

Share of total energy transfer through building envelopes driven by glass components

35%

Higher heating energy demand in buildings with high window-to-wall ratio (north/east)

1.5 to 5x

Increase in cooling energy demand when window-to-wall ratio goes from 10% to 90%

20%

Performance improvement over state-of-the-art smart shading solutions

33%

Targeted reduction in manufacturing cost vs. current smart glass

50+

Windows replaced in real-building demonstrations

200 m²

Glass facade area demonstrated

4.7 billion m²

Annual building glass market size

<0.7 W/(m²K)

U-value of smart insulating glass unit

<2%

Weight increase compared to standard low-E IGU

1500 x 5000 mm²

Large-area electrochromic cell size demonstrated

The business problem

What needed solving

Commercial and public buildings with large glass facades face a costly dilemma: big windows look great and let in natural light, but they drive heating costs up by 35% in winter and multiply cooling costs by up to 5x in summer. Current smart glass solutions exist but are too expensive and too heavy for widespread adoption, keeping most of the 4.7 billion square meter annual glass market stuck with passive, energy-wasting windows.

The solution

What was built

The project built a combined electrochromic and thermochromic smart insulating glass unit — a window that both self-tints with temperature changes and can be electrically switched on demand. Prototypes were manufactured at production-relevant sizes (EC cells up to 1500 x 5000 mm², TC glass in 4000 x 300 mm² rolls), achieving U-values below 0.7 W/(m²K) with less than 2% weight increase. These were installed and monitored in a Greek hospital and a Swedish office building.

Audience

Who needs this

Commercial real estate developers building glass-heavy office towersHospital and healthcare facility managers dealing with overheating and high energy billsGlass and window manufacturers looking for next-generation smart glass productsBuilding retrofit companies targeting energy performance upgradesArchitectural firms designing energy-efficient commercial buildings

Business applications

Who can put this to work

Commercial Real Estate

enterprise

Target: Property managers and building owners with large glass facades

If you are a commercial real estate company dealing with high cooling and heating bills from large glass facades — this project developed a smart insulating glass unit that automatically adjusts how much heat and light passes through. The demos showed energy savings in buildings where over 50 windows and 200 m² of glass facade were replaced, with the glass adding less than 2% extra weight to existing frames.

Glass & Window Manufacturing

mid-size

Target: Insulated glass unit manufacturers looking for next-generation products

If you are a glass manufacturer looking to move beyond standard low-E coatings — this project built a combined electrochromic and thermochromic insulating glass unit at production-relevant sizes (EC cells up to 1500 x 5000 mm²). The manufacturing cost target is 33% lower than current smart glass solutions, opening up the 4.7 billion square meter annual building glass market.

Healthcare Facility Management

enterprise

Target: Hospital operators managing patient comfort and energy costs

If you are a hospital facility manager struggling with overheating in patient rooms with large windows — this project demonstrated its smart glass in a hospital in Athens, Greece. The glass automatically switches its solar energy transmission, reducing cooling demand that can increase by a factor of 1.5 to 5 as window area grows, while maintaining patient comfort with U-values below 0.7 W/(m²K).

Frequently asked

Quick answers

What does this smart glass cost compared to current solutions?

The project targeted a 33% reduction in manufacturing cost compared to state-of-the-art smart shading solutions. Exact per-square-meter pricing is not disclosed in the available project data, but the cost advantage comes from combining two technologies (electrochromic and thermochromic) into one lightweight unit instead of separate systems.

Can this be manufactured at industrial scale?

The project demonstrated electrochromic cells on polymer webs at sizes up to 1500 x 5000 mm² and thermochromic glass in rolls up to 4000 x 300 mm². These are production-relevant dimensions. The consortium includes 6 industrial partners, which suggests a clear path toward manufacturing scale-up.

Who owns the intellectual property and can I license this technology?

The project was coordinated by Fraunhofer (Germany), a leading applied research organization. IP is typically shared among the 12 consortium partners across 6 countries. Licensing discussions would need to go through Fraunhofer and the relevant industrial partners in the consortium.

How much energy does this actually save?

The project objective states that 25 to over 60% of total energy transfer through building envelopes is driven by glass components, and cooling demand increases by a factor of 1.5 to 5 with larger window areas. The smart glass targets a 20% performance improvement over current smart shading. Exact measured savings from the Athens and Uppsala demos are in the final project reports.

Does this work with existing window frames and building systems?

The smart insulating glass units add less than 2% weight compared to standard low-E IGU, meaning existing frames and support structures should handle the upgrade. The electrochromic component requires electrical connection for switching, while the thermochromic component switches automatically based on temperature (below 30°C threshold).

Is this technology ready to install today?

The project ended in September 2023 and successfully demonstrated prototypes in two real buildings — a hospital in Athens and an office in Uppsala — with at least one year of continuous monitoring. The technology has been piloted but is not yet a commercial off-the-shelf product. Contact the consortium for current commercialization status.

Does this meet building energy regulations?

The smart IGU achieves a U-value below 0.7 W/(m²K), which meets or exceeds current energy performance requirements in most European countries. The visible light and solar energy transmission can be modulated from 50% down to 10%, giving architects and building managers active control over energy performance compliance.

Consortium

Who built it

The Switch2save consortium of 12 partners across 6 countries (Belgium, Czech Republic, Germany, Greece, Latvia, Sweden) is well-balanced for bringing smart glass to market. Half the partners (6) are from industry, including 2 SMEs, which means commercial interests are driving the project alongside Fraunhofer's applied research leadership. The two demo sites — a hospital in Greece and an office in Sweden — cover both Mediterranean and Nordic climates, proving the technology works across Europe's range of weather conditions. With 21 total deliverables and 4 dedicated demonstration outputs, this is a consortium that built and tested real products, not just published papers.

ETHNICON METSOVION POLYTECHNIONparticipant · EL
CHROMOGENICS ABparticipant · SE
VAN ROMPAEY SARAparticipant · BE
AMIRES THE BUSINESS INNOVATION MANAGEMENT INSTITUTE ZUparticipant · CZ
E2ARC ARCHITECTURE RESEARCH FOR CITIESparticipant · BE
ZAPADOCESKA UNIVERZITA V PLZNIparticipant · CZ
AMIRES SROparticipant · CZ

How to reach the team

Fraunhofer Gesellschaft (Germany) — contact through SciTransfer for a warm introduction to the project team

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Next steps

Talk to the team behind this work.

Want to explore licensing or partnership opportunities with the Switch2save consortium? SciTransfer can arrange a direct introduction to the right people on the team.

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