Solar Control Glass for Homes in the UK
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Solar Control Glass: Types, Performance Data, Pros & Cons
Solar control glass is coated glazing specifically designed to limit solar heat gain while maintaining natural daylight—a critical consideration for architects, specifiers, and homeowners across the UK and EU. With European summers growing hotter (the UK recorded 40.3°C in July 2022), urban overheating becoming endemic, and tougher regulations like UK Building Regulations Part O and Part L revisions now in force, understanding this technology has never been more important. In recent years, there has been a 61% increase in the demand for solar control glass, reflecting a growing emphasis on energy efficiency in building design.
This guide covers:
How solar control glass works and its key performance metrics
A comparison table of glass types from 70/37 to 29/18
Advantages and disadvantages for real-world projects
FAQs and technical references
Typical applications include large south- and west-facing façades, rooflights, atria, conservatories, sliding doors, and curtain walling in offices, schools, and hospitals.
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What Is Solar Control Glass?
Solar control glass is float glass with a microscopically thin metallic or oxide coating designed to reflect and absorb solar heat while permitting high levels of natural light, making it a core technology in architectural and structural glazing for modern building design. This solar control coating is different from low e glass, though the two are often combined: solar control targets incoming solar radiation, while low e coating targets heat loss from inside to outside.
The coating is typically applied via magnetron sputtering (soft coat) in a vacuum chamber onto clear or low-iron glass in thicknesses from 4–10mm. Modern solar control glass is available in various finishes, including tints and neutral options, and some coatings are nearly invisible. Solar control glass can be categorized into various types, including tinted glass, reflective, and neutral options, each designed to manage the amount of heat and light passes through windows.
Light transmission ranges from approximately 70% for very neutral products down to about 29% for strong solar control. Products like the COOL-LITE SKN range of solar control glass are engineered to provide neutral solar control, making them suitable for both commercial buildings and residential projects with large glazed areas.
How Does Solar Control Glass Work?
Standard glass creates a greenhouse effect: shortwave solar energy enters easily, but longwave infrared radiation becomes trapped inside, raising indoor heat. Solar control glass works by utilizing a combination of reflection, absorption, and transmission to manage the amount of solar heat and light entering a building.
Here’s what happens to the solar spectrum:
Visible light: A controlled portion transmits through for natural daylight, maintaining brightness without excessive glare
Infrared radiation: A significant portion is reflected or absorbed by the selective coating, preventing excess thermal energy from entering the indoor space
UV rays: Partly blocked, reducing fading of furniture, textiles, and artworks
Solar control glass acts as a high-tech filter, allowing natural light to enter while reflecting a significant portion of the sun’s heat away. The selective coating allows visible daylight to enter while reflecting away infrared rays, preventing excess heat from entering the interior. This has a significant impact on reducing carbon emissions from mechanical cooling systems.
Modern neutral soft-coat products use double-silver or triple-silver layers with dielectric spacers to minimise colour shift, so the glass appears clear or only slightly tinted from inside. Hard-coat pyrolytic products offer processing flexibility for toughening and laminated applications.
Key Performance Metrics: Light, Solar Factor, Ug & Reflection
Performance is quantified using standard metrics published to EN 410 and EN 673 for double glazing or triple glazing units. Understanding these values, particularly U-values and thermal performance of glass, is essential for achieving optimal thermal performance and energy performance in any project.
Visible Light Transmission (TL): The percentage of natural daylight passing through. A TL of 70% maintains bright interiors similar to standard glass, while 29% prioritises heat rejection over brightness.
Solar Factor / G Value (SHGC): The Solar Heat Gain Coefficient measures a window’s ability to transmit solar energy into a room, with lower values indicating better insulation against solar heat buildup. The g value measures the percentage of solar energy that penetrates the glass; a lower g value indicates better heat rejection. Solar control glass typically balances low g value with high light transmission to maintain brightness while ensuring thermal comfort.
Ug Value (W/m²K): The rate of heat transfer through the insulated glazing unit. Typical double-glazed solar control units achieve Ug around 1.0–1.2 W/m²K, providing good thermal insulation against heat loss. Triple glazing can reach 0.5–0.7 W/m²K.
External Reflection (%): The proportion of visible light reflected outside. Values of 11–17% create a slightly mirrored façade while maintaining clear views from inside, offering daytime privacy and aesthetic options.
The trade-off is inherent: higher light transmission often correlates with a higher solar factor (more heat), while very low g values require lower TL and sometimes higher reflection.
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Comparison of Solar Control Glass Types
The following table compares a family of neutral solar control glass types commonly specified in Europe, ranging from high-light to strong solar control. These represent typical performance values for double-glazed units with 16mm argon cavity.
Example Specification Scenarios
Example 1 – Manchester Apartments: A UK apartment block with partially shaded façades chooses 70/37 glass on east and west elevations. This maximises winter daylight for the building’s occupants while still moderating summer heat gain—ideal for temperate climates where overcast conditions are common.
Example 2 – Seville Office: A commercial façade in southern Spain deploys 42/23 or 29/18 on south-facing curtain walling. This keeps internal temperatures manageable during summer months without oversizing air conditioning systems, cutting cooling energy consumption by 15–30%.
Example 3 – Berlin Passivhaus: Triple-glazed rooflights use a mid-range product (60/32) to balance passive solar gains in winter against overheating risk in July and August, combined with excellent Ug values around 0.6 W/m²K for overall energy performance, similar to how structural glass roof systems with solar control options are specified in high-performance projects.
Type | Light Transmission (TL) | G Factor / SHGC | Ug Value (W/m²K) | External Reflection |
|---|---|---|---|---|
Type A (70/37) | 70% | 0.37 | 1.0 | 11% |
Type B (60/32) | 60% | 0.32 | 1.1 | 13% |
Type C (42/23) | 42% | 0.23 | 1.0 | 15% |
Type D (29/18) | 29% | 0.18 | 1.1 | 17% |
Advantages of Solar Control Glass
Benefits depend on climate, orientation, and glazing area, but well-chosen control glass can significantly improve comfort and reduce energy consumption, especially when delivered as part of a fully designed structural and architectural glazing solution.
Thermal comfort: Reduced solar gains prevent overheating in living rooms, offices, and conservatories. Studies indicate peak temperature reductions of 3–5°C compared with clear double glazing. Solar control glass helps to reduce solar gain, which can prevent overheating in buildings, particularly those with south-facing windows.
Energy savings: Solar control glass can significantly reduce the need for mechanical cooling, leading to energy savings in buildings by minimizing solar heat gain. Potential cooling savings reach 15–30% in highly glazed buildings in hot climates, making buildings more energy efficient.
Glare control: Controlled solar glare from solar control glass reduces glare on screens and creates a more comfortable environment in homes and offices. Using the right glazing specification can bring in more natural light while controlling glare, significantly improving well being for occupants.
UV and fade protection: Solar control glass can filter out a significant portion of harmful UV radiation, preventing fading of furniture and other interior items by 50–70% compared with uncoated standard glass.
Aesthetics and privacy: External reflection of 11–17% provides a modern appearance and daytime privacy without compromising views.
Regulatory compliance: Combining solar control glass with good design supports Part O (overheating), Part L (conservation of fuel and power), and credits for BREEAM/LEED certification, reducing carbon emissions.
Solar control glass can enhance the overall comfort of a building by balancing natural daylight with heat reduction, which can improve productivity in workspaces.
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Disadvantages and Limitations
While highly beneficial in many cases, solar control glass is not a universal solution.
Higher initial cost: Coated solar control units typically cost 20–50% more than standard clear double glazing due to complex manufacturing. Payback depends on cooling load and energy prices.
Reduced passive solar gains: Low g values limit valuable winter solar gain in cold climates, potentially increasing heating demand if used on all orientations without consideration.
Lower daylight with stronger products: Very strong solar control (around 29% TL) can make interiors feel darker, especially in deep floor plates or regions with overcast winters, requiring artificial lighting.
Colour and reflection effects: Some products show a subtle green tint or mirror-like appearance at certain angles, which may not suit traditional architecture or conservation areas.
Orientation sensitivity: Incorrect selection (very low g value on north façades) compromises passive design principles.
Retrofit constraints: Heritage or listed buildings may restrict replacement glazing, requiring secondary glazing or shading devices instead.
Applications: Where to Use Solar Control Glass
Optimal performance comes from combining the right solar glass with good orientation, shading, and ventilation design.
Residential: South- and west-facing patio doors, panoramic windows, and bespoke Oriel windows that maximise natural light and views in new-build homes benefit significantly. Conservatory and orangery roofs added to UK homes after 2010 where overheating has become problematic are prime candidates.
Commercial: Curtain walling on offices, hotels, and hospitals with large glass panes benefits from commercial applications of solar control. Atriums, entrance lobbies, restaurant frontages, and showroom fronts requiring transparency but suffering from solar gain see marked improvements when combined with architectural glazing in culinary and hospitality spaces.
Rooflights and skylights: Flat rooflights and glazed roofs over shopping centres and transport hubs—where direct sunlight is highest—require strong solar control with g values around 0.18–0.25, as demonstrated by large-scale structural skylight projects like the UK’s largest bespoke glass skylight installation.
Climate considerations: Mediterranean and hot climates demand stronger products (g values 0.18–0.25), while temperate climates like the UK, Ireland, and Benelux suit mid-range products (0.30–0.37). Integration with external louvres or brise-soleil provides optimal flexibility in very exposed locations.
FAQ
FAQs About Solar Control Glass
No. Solar control glass targets incoming solar radiation to reduce heat gain, while e glass (low-E) minimises heat loss from inside. Many modern glazing units combine both functions in a single coating system for optimal thermal performance.
High-light products (around 70% TL) remain very bright, similar to clear glass. Stronger products (around 29% TL) noticeably reduce daylight. Correct product selection for your orientation avoids a gloomy appearance.
Most modern uPVC, aluminium, and timber frames accept replacement double-glazed units. Frame depth, glazing bead design, and building regulations must be verified by a qualified installer, and many homeowners choose to start with a specialist architectural glazing enquiry and consultation.
Yes—it still provides thermal insulation (especially with low-E coatings) but reduces passive solar gains. In mild UK winters, the trade-off favours comfort; in very cold climates, orientation-specific selection is critical
With hotter summers (UK heatwaves in 2018, 2019, 2022) and temperatures reaching 40°C+, south- and west-facing rooms with large glazing benefit substantially, as shown in UK residential projects that use extensive corner and roof glazing to maximise light while managing heat. Payback is typically 5–10 years at current energy prices, particularly where designs echo light-maximising residential glazing schemes.
Yes. Many modern coatings work with triple-glazed units, achieving Ug values of 0.5–0.7 W/m²K combined with tailored g values for Passivhaus and net-zero projects, similar to the high-performance detailing seen in glass link corridors connecting residential spaces and structural glass rooflight house extensions.
Sources and References
Performance data and concepts in this guide rely on established European standards and manufacturer technical documentation.
EN 410: Glass in building – Determination of luminous and solar characteristics of glazing
EN 673: Glass in building – Determination of thermal transmittance (Ug value)
UK Building Regulations Approved Document O (Overheating), 2021 edition with 2022 amendments
UK Building Regulations Approved Document L (Conservation of fuel and power), 2021 edition
Technical brochures from major architectural glass manufacturers including Guardian SunGuard.
Industry reports on overheating and solar gains in highly glazed buildings (2018–2025)
Specific numerical values for g factors, light transmission, and Ug have been cross-referenced against published manufacturer datasheets to ensure accuracy. Always consult current product specifications when specifying for your project.