Dear group,
The InputOutputReference states that:
"Fraction Visible: The fraction of heat from lights that goes into the zone as visible (short-wave) radiation. The program calculates how much of this radiation is absorbed by the inside surfaces of the zone according the area times solar absorptance product of these surfaces."
How exactly does this relate to luminous efficacy of the applied lighting system (and luminaire efficiency)?
If I take an T8 fluorescent tube with a luminous efficacy of 80 lm/W, then I would say that the fraction visible is about 12% (80/683, where 683 lm/W is the number of lm/W of a hypothetical monochromatic green light source that would have 100% of its energy visible).
This is clearly less than the 18% that is given as a reference value for fluorescent lighting in the table below the definition of Fraction Visible. The second sentence of the definition indicates that absorption of this radiation is calculated using solar absorptance, implying that the spectral range of the radiation is broader than the visible range. Does this explain the higher value of 18%?
Best Regards,
Wouter
The InputOutputReference states that:
"Fraction Visible: The fraction of heat from lights that goes into the zone as visible (short-wave) radiation. The program calculates how much of this radiation is absorbed by the inside surfaces of the zone according the area times solar absorptance product of these surfaces."
How exactly does this relate to luminous efficacy of the applied lighting system (and luminaire efficiency)?
If I take an T8 fluorescent tube with a luminous efficacy of 80 lm/W, then I would say that the fraction visible is about 12% (80/683, where 683 lm/W is the number of lm/W of a hypothetical monochromatic green light source that would have 100% of its energy visible).
This is clearly less than the 18% that is given as a reference value for fluorescent lighting in the table below the definition of Fraction Visible. The second sentence of the definition indicates that absorption of this radiation is calculated using solar absorptance, implying that the spectral range of the radiation is broader than the visible range. Does this explain the higher value of 18%?
Best Regards,
Wouter
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