BS EN 16795 is a European Standard that discusses plastics and polymers.
BS EN 16795 specifies a method for estimating the temperature increase of a flat polymer surface, due to its solar radiant energy absorption, compared to the ambient temperature.
For that purpose, a specimen and black and white reference plates are exposed to simulated solar radiation under specified conditions (simulated solar radiation, ambient air temperature, convective flow). For opaque specimens, a thermally sensitive electrical element at the backside or a pyrometer is used to measure the surface temperature. For translucent specimens, a pyrometer is used to measure surface temperature.
Note: Some specific polymeric materials are translucent (transparent) and might have a transmittance window in a wavelength range where the used pyrometer is sensitive (e.g. polyethylene). The surface temperature of these materials cannot be measured with the contact and the contactless method.
BS EN 16795 on methods of determining heat build up is relevant to:
Solar radiation causes the temperature of irradiated surfaces to rise substantially above the
temperature of the surrounding air. The resulting surface temperature depends on the climatic parameters at the location in question, the spectral absorption of the surface, the geometric dimensions and on the specific structure of the object. Generally, the darker the colour, the more the sun's energy is absorbed and the higher is the heat build-up.
The performance characteristics of most of the materials are also defined by the in-service temperature. Such materials can be window profiles or other polymeric carrier materials. The micro climate at house walls is also defined by the absorbed solar radiation (depending on the material properties). The same applies for interior room and automobile temperatures.
The examples reveal the significance of the knowledge of the temperature of sun irradiated surfaces. If the temperature magnitude is estimated to be critical, provisions can be taken to optimize the in-service micro climate, e.g. reduction of the in-service temperature by improvement of the spectral reflection characteristics or appropriate change in design and improving the air conditioning.
In this regard, BS EN 16795 is useful to determine the extent of thermal degradation of polymers by solar radiation, which is a decisive factor for product development.
EN 16795:2015