Evaluating the Effectiveness of Ultraviolet and Infrared Heat-Insulating Films in Energy-Efficient Buildings

Introduction: The Role of Window Films in Energy-Efficient Building Design

Energy-efficient buildings are no longer defined solely by high-performance HVAC systems or renewable energy installations. Increasingly, attention is shifting toward the building envelope, where uncontrolled solar radiation through glass remains a major source of energy loss and thermal discomfort. As modern architecture favors large glazed façades, the need for effective solar management solutions has become critical.

Ultraviolet and infrared heat-insulating films represent a passive energy-efficiency strategy designed to improve glazing performance without altering building structure. By controlling specific portions of the solar spectrum, these films reduce cooling demand, improve indoor comfort, and support long-term energy efficiency goals. This article evaluates the effectiveness of ultraviolet and infrared heat-insulating films in energy-efficient buildings, focusing on their fundamental principles, performance metrics, and measurable impact on building energy performance.

Fundamentals of Ultraviolet and Infrared Heat-Insulating Films

Solar radiation reaching building glass consists primarily of visible light, ultraviolet (UV), and infrared (IR) energy. While visible light contributes to daylighting, UV radiation is responsible for material degradation, and IR radiation is the primary driver of solar heat gain.

Ultraviolet heat-insulating films are designed mainly to block UV radiation, typically achieving up to 99 percent UV rejection. This function protects interior finishes, furnishings, and occupants from long-term exposure. However, UV radiation accounts for only a small portion of total solar heat entering a building.

Infrared heat-insulating films address the dominant source of thermal gain by selectively rejecting infrared energy. Advanced films combine UV and IR control using technologies such as nano-ceramic coatings, metalized layers, or spectrally selective films. These coatings are engineered to reflect or absorb infrared wavelengths while maintaining controlled visible light transmission.

Unlike external shading systems or glass replacement, ultraviolet and infrared heat-insulating films function as passive solar control solutions. Once applied to existing glazing, they continuously regulate solar radiation without mechanical operation, electricity consumption, or changes to the building structure, making them particularly suitable for energy-efficient retrofits.

Key Performance Metrics for Evaluating Film Effectiveness

Assessing the effectiveness of ultraviolet and infrared heat-insulating films requires a clear understanding of standardized performance metrics that directly influence building energy efficiency.

Ultraviolet rejection measures the film’s ability to block UV radiation and is primarily associated with interior protection and occupant health. Infrared rejection indicates how effectively the film reduces radiant heat transfer, directly affecting indoor temperature and cooling demand.

Total solar energy rejected (TSER) represents the overall percentage of solar energy prevented from entering the building. A higher TSER value generally corresponds to greater thermal performance. Solar heat gain coefficient (SHGC) quantifies how much solar heat passes through the glazing system; lower SHGC values indicate better heat control and improved energy efficiency.

Visible light transmission (VLT) measures the percentage of natural light allowed through the glass. Effective heat-insulating films balance IR rejection and TSER with sufficient VLT to maintain daylighting and visual comfort.

Together, these metrics provide a comprehensive framework for evaluating how ultraviolet and infrared heat-insulating films contribute to energy-efficient building performance, beyond simple UV protection alone.

Impact on Building Energy Performance

In a mid-rise office building located in a hot–summer climate, large glazed façades led to excessive solar heat gain and high cooling demand, particularly during afternoon peak hours. Despite efficient HVAC systems, indoor temperatures near windows remained unstable, increasing air-conditioning runtime.

As a retrofit solution, ultraviolet and infrared heat-insulating films—commonly specified in commercial projects as commercial window tint and classified as architectural film for windows—were applied to the existing glazing. After installation, infrared transmission and solar heat gain were significantly reduced, resulting in more stable indoor temperatures and lower peak cooling loads. HVAC operation efficiency improved, while occupant comfort near glazed areas increased noticeably.

Overall, this case demonstrates how ultraviolet and infrared heat-insulating films serve as an effective demand-side energy optimization measure, enhancing the performance of energy-efficient building systems through improved solar management.

Evaluating Effectiveness Through Energy and Performance Outcomes

The effectiveness of ultraviolet and infrared heat-insulating films in energy-efficient buildings lies in their ability to control solar radiation at the glazing level. While UV protection safeguards interiors and occupants, infrared control addresses the primary source of unwanted heat gain, delivering measurable improvements in energy performance.

By evaluating these films through standardized performance metrics such as IR rejection, TSER, SHGC, and VLT, building professionals can assess their real impact on cooling demand and operational efficiency. As energy codes tighten and sustainability targets become more stringent, ultraviolet and infrared heat-insulating films offer a technically sound, low-disruption solution for improving building energy efficiency.

For architects, engineers, and building owners, these films represent a practical and scalable strategy to enhance thermal performance, reduce energy consumption, and support long-term energy-efficient building design.

References

Solar Film S70 — balanced heat control with high daylight transmission.
Solar Film BL70 — enhanced infrared rejection for warm climates.
Solar Film C955 — spectrally selective performance for energy efficiency.
Solar Film C6138 — nano-ceramic technology for glare and heat reduction.
Residential & Office Window Film Series — complete window film solutions for homes and workplaces.