The ISO 9050 is an internationally recognized standard that defines how to measure the performance of glazing products like Solar Window films. It sets common rules for calculating how much light, heat, and solar energy is transmitted through these materials from the sun. It’s a global benchmark that says a lot about how effective a glazing material is.
This article explains ISO 9050 testing protocols. It explains its importance and also provides insights to interpret its metrics which is helpful in making informed decisions as regards the installation of solar window films in commercial and residential buildings.
Why ISO 9050 Is Crucial For Evaluating Solar Film Performance
The ISO 9050 standard provides a basis for comparison and data certification between different brands. Instead of relying on a firm’s marketing claims, you can evaluate window film performance yourself based on its ISO 9050 metrics. This makes the standard a tool for objectivity in a saturated market with competing products.
Furthermore, ISO 9050 is widely referenced by other standards and software. Its indicators, such as the Solar Heat Gain Coefficient (SHGC), can be plugged into simulation programs to model the performance of different types of products.
This information can be used to make tangible predictions to lower the energy bills of a building. It is also a useful metric to secure finance from appropriate bodies, meet green building certifications, and generally make better plans for the future.
Key ISO 9050 Metrics And What They Mean
1. Visible Light Transmittance (VLT).
VLT is the percentage of visible light that passes through a material. It is expressed as a percentage from 0% to 100%, or as a decimal from 0 to 1. A VLT of 100% means all visible light passes through a material.
In general, window films with high VLTs give you brighter interiors with loads of natural light. However, they perform poorly in reducing glare. Conversely, films with low VLTs offer more shade and glare protection but they make rooms darker.
2. Total Solar Energy Transmittance (g-value or Solar Heat Gain Coefficient)
This is arguably the most important metric for solar control. It measures the total amount of solar heat that passes through a material both directly and indirectly.
Materials with a low g-value are highly effective at reducing solar heat gain. This lowers the load on air conditioning systems, which slashes energy costs significantly.
3. Total Solar Energy Rejected (TSER).
This metric expresses the total amount of solar heat energy that a window film blocks from entering a building. It’s the opposite of the total solar energy transmittance. And like SHGC, it is another crucial solar indicator that helps with controlling heat and cold in a building.
4. Light Reflectance (internal and external)
This is the portion of visible light that is reflected by the outside and inside surfaces of a material. This property influences the appearance of the material and dictates the potential magnitude of glare for occupants and outsiders.
Materials with a high external reflectance reject heat effectively but tend to have a mirrored or glossy look. This can be an environmental issue, especially in some urban areas. Window films with low internal reflectance improve comfortability because reflection is at a minimum.
5. UV Transmittance.
This metric dictates the amount of ultraviolet radiation that is transmitted through a material. The lower a window film’s UV transmittance, the better it protects furniture, rugs, textiles and artworks in a space from fading.
6. Selectivity Ratio
This ratio is considered the "intelligence" metric for solar films. It compares the amount of light transmitted to the total heat blocked by the film.
The higher the Selectivity Ratio of a film, the better its performance. It means that the fixture is efficient at separating light from heat. A film with VLT of 60% and g-value of 0.3 has a Selectivity Ratio of 2, which is considered excellent.
Finding The Perfect Window Film For Your Building
The perfect window film solution for any building depends majorly on your preference among other things. Low g-value films installed on west and south facing buildings do a good job of lowering internal temperatures during peak hours. This eases the load on HVAC systems and directly translates into lower operating costs and better comfortability, especially in glass-heavy commercial buildings.
Visible Light Transmittance helps to strike the right compromise between daylight visibility and glare. In open-plan offices or schools, a mid-range VLT film might be the best choice. It’ll provide the right mix of natural light whilst limiting glare, reflection and discomfort near windows. In areas where there are a lot of screens, films with lower VLT might be the better option.
Conclusion
ISO 9050 is a common language that describes how glazing materials interact with solar energy. Its metrics aids homeowners and professionals to compare products fairly and make informed decisions about what’s best for their facilities in terms of comfort, aesthetics and energy savings.
Solar Screen is known for their premium collection of ISO 9050 certified window films. These fixtures are highly rated and they have the rubber stamp approval of industry experts. For more insights about our energy-saving window films and the many benefits they offer, explore our blog and case studies.