The BF5 Sunshine Sensor for building energy management systems

The compact innovative BF5 Sunshine Sensor measures Global and Diffuse solar radiation, and Sunshine Duration.

• Measures Global (Total) and Diffuse radiation
• Measures Sunshine Duration
• No moving parts, no shade rings, no motorised tracking
• Outputs can be set to Energy (W.m ^-2), PAR ( μmol.m^-2.s^-1) or Lux
  
  

The ability to control the response of powered blinds and louvres to sunlight is a tricky challenge. For example, total incident radiation may be high, but if the radiation is arriving as diffuse light there may be no need to adjust the blinds. On the other hand, the total solar radiation level could be low, but if most of the energy is in the direct beam (e.g. low level winter sun), louvre adjustment may be necessary to shield occupants from glare.

The BF5 Sunshine Sensor offers system developers a unique tool for obtaining diffuse and direct solar radiation from a single, compact device. In addition it does not need to be adjusted or repositioned to track the sun – an advantage over devices with shadow rings.

The BF5 features a patented design - using an array of photodiodes with a unique computer-generated shading pattern to measure incident solar radiation. A microprocessor calculates the Global and Diffuse components of the radiation and determines the sunshine status. This algorithm corresponds closely to the World Met Office threshold of 120 W/m ^-2 for sunshine duration.

Outputs can be set to Energy (W.m^-2), PAR (μmol.m ^-2.s^-1) or Lux. Two analogue voltage outputs are provided for the Global and Diffuse radiation - and the sunshine state is represented by a digital output (contact closure). A built-in heater keeps the BF5 clear of dew, ice and snow down to -20°C.