# Team:Cambridge/Tools/Lighting

(Difference between revisions)
 Revision as of 20:08, 26 October 2010 (view source)Willh (Talk | contribs) (→Bringing it all together)← Older edit Revision as of 20:08, 26 October 2010 (view source)Willh (Talk | contribs) (→Bringing it all together)Newer edit → Line 136: Line 136: Now we combined the above calculations. If we assume that the tree absorbs all light passing through its projected area '''A''' (not a bad approximation, since only a few percent is able to make it through the canopy) then the total radiant light energy falling on it during the day time per second is '''60*A''' W. If the total radiant energy outputted at night per second is '''E''', then the luminous flux is '''471.13E''' lm, which we desire to be as bright as a street lamp '''X''' lm, then combining these we find that the total efficiency of our plant has to be: Now we combined the above calculations. If we assume that the tree absorbs all light passing through its projected area '''A''' (not a bad approximation, since only a few percent is able to make it through the canopy) then the total radiant light energy falling on it during the day time per second is '''60*A''' W. If the total radiant energy outputted at night per second is '''E''', then the luminous flux is '''471.13E''' lm, which we desire to be as bright as a street lamp '''X''' lm, then combining these we find that the total efficiency of our plant has to be: - Efficiency = (X*Tnight) / (471.13*60A*Tday) + '''Efficiency = (X*Tnight) / (471.13*60A*Tday)''' where '''Tday''' and '''Tnight''' are the hours of daylight and night time respectively. If we choose the least bright street lamp ('''X=210''') and hypothesise a projected area of '''A=30m2''', and a '''day:night ratio 14:10'''  then we find that the efficiency must be roughly '''0.02%'''. This means that 0.02% of the total energy hitting the tree must be converted eventually into light output, a potentially achievable target. where '''Tday''' and '''Tnight''' are the hours of daylight and night time respectively. If we choose the least bright street lamp ('''X=210''') and hypothesise a projected area of '''A=30m2''', and a '''day:night ratio 14:10'''  then we find that the efficiency must be roughly '''0.02%'''. This means that 0.02% of the total energy hitting the tree must be converted eventually into light output, a potentially achievable target. {{:Team:Cambridge/Templates/footer}} {{:Team:Cambridge/Templates/footer}}