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What is Visible Light Transmission (VLT)?

Energy savings Solar window film Advice for glazing professionals

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What is Visible Light Transmission (VLT)?

Visible Light Transmission (VLT) is a key performance indicator that determines the effectiveness and functionality of solar films in commercial installations. For specialized installers managing large-scale projects in office complexes, hotels, and commercial spaces, understanding VLT is crucial to ensure optimal results that meet technical specifications and client expectations.

Understanding Visible Light Transmission

Visible Light Transmission represents the percentage of visible light passing through a solar film. Measured on a scale from 0% to 100%, VLT directly influences the transparency and optical clarity of glazing systems. This parameter becomes especially significant in commercial installations where precise light control can impact occupant comfort, energy efficiency, and aesthetic requirements.

The VLT value is measured using specialized spectrophotometric equipment that measures light transmission across the entire visible spectrum (380-780nm). This technical specification allows installers to precisely match films to project requirements and ensure consistent performance in large-scale installations.

Critical Considerations for Large-Scale Installations

Visual Comfort and Productivity

High-performance solar films must balance light transmission and glare reduction. In office environments, maintaining an adequate level of natural light (typically 40-70% VLT) while eliminating glare on digital screens is crucial for occupant productivity. The VLT of the film directly impacts the quality of the indoor environment and can significantly affect work efficiency.

Energy Performance

VLT works in synergy with other solar performance metrics, especially the Solar Heat Gain Coefficient (SHGC). Lower VLT values generally correspond to better solar heat rejection, but the relationship is not linear. Understanding this interaction is critical to optimizing both visual comfort and energy efficiency in large commercial spaces.

Selecting Appropriate VLT Levels

High VLT Applications (50-70%)

Open-plan offices that require maximum natural light
Commercial environments where product visibility is key
Healthcare facilities requiring clear visibility
North-facing facades with minimal direct sunlight exposure

Medium VLT Applications (30-50%)

Standard office spaces
Hotel common areas
Educational institutions
East/west-facing facades

Low VLT Applications (15-30%)

Computer-intensive workspaces
South-facing facades with strong sun exposure
Areas requiring privacy
Data centers and server rooms

Regulatory Compliance and Standards

Commercial installations must adhere to specific building codes and energy regulations. Key points to consider:

Energy Codes: Many jurisdictions require minimum VLT values for occupied spaces
Safety Standards: Emergency exit requirements may limit minimum VLT values
Energy Certifications: The contribution of VLT to the building's overall energy performance

Technical Specifications and Performance Verification

Professional installers should always check:

Spectral performance data
Angular performance variations
Post-installation VLT measurements
Integration with existing glazing systems

Why Partner with Solar Screen?

Solar Screen specializes in supporting specialized installers with:

Technical Excellence: Complete spectral data for all products
Advanced Test Installations: Performance verification
Technical Documentation: For building certification
Project Support: Customized VLT calculations for complex glazing systems
On-Site Technical Consultation: Fast sampling service for client approval
Installation Efficiency: Large format rolls for efficient installations
Consistent Batch Quality: For uniform appearance
Training and Certification Programs: Specialized training for installers

Expert Support for Your Next Project

Selecting the optimal VLT for large-scale installations requires careful analysis of multiple factors. The Solar Screen technical team provides detailed support throughout the specification process, ensuring the right product selection for your specific application.