Why LEDs are lead­ing lights


Fears from Palmer­ston North res­i­dents about in­creased crime, road and per­sonal safety is­sues, and trip­ping over on un­even pave­ments in the dark, have ac­com­pa­nied the changeover of city street­lights to LEDs.

But con­cerns about the bright­ness or oth­er­wise of the new lights can be over­come, ac­cord­ing to LED light­ing spe­cial­ist Hangfeng Ji.

‘‘Switch­ing to LED light­ing is not only for en­ergy sav­ing, but also for in­creas­ing the safety of the road and the city,’’ Ji said.

A re­search and de­vel­op­ment man­ager for Bi­o­lu­mic, a Palmer­ston North start-up com­pany spe­cial­is­ing in agri­cul­tural light­ing, he of­fered to ‘‘shed some light’’ on why LED tech­nol­ogy on our streets had a bright fu­ture.

‘‘It’s not a one-to-one switch [from old to new] - it’s not that sim­ple. LEDs are very bright from a highly con­cen­trated source point but they can be dif­fused. The lights can be de­signed to to be sim­i­lar to the old sodium lights.’’

Ji said this can be achieved by us­ing a greater num­ber of smaller LEDs in­stead of a larger sin­gle light, or by us­ing ad­vanced op­tics around the bulb to cre­ate a dif­fus­ing ef­fect.

With nearly 10 years in the light­ing in­dus­try, Ji worked as a sci­en­tist for Philips Re­search in Shang­hai, im­mi­grat­ing to New Zealand three years ago.

An in­ven­tor with more than 40 patents, mainly in the LED light­ing field, he said the LEDs use up to 85 per cent less en­ergy and can last for 10 years.

They could also be com­bined with other city util­i­ties, such as elec­tric-car charg­ing, se­cu­rity and sur­veil­lance, mo­bile phone base sta­tions and emer­gency ser­vices, he said.

‘‘In other words, LED light­ing can not only save en­ergy but, more im­por­tantly, make the city smarter.’’

LED tech­nol­ogy means fur­ther en­ergy sav­ings are pos­si­ble be­cause the in­ten­sity of the light can be re­duced by 20 or 30 per cent dur­ing off-peak times, he said.

‘‘Light­ing on de­mand’’, Ji said, used sen­sors to brighten the lights when ve­hi­cles or peo­ple were de­tected, and dim them when they were not re­quired.

‘‘Dim­ming LEDs is very easy but not pos­si­ble with older light­ing sys­tems, which can’t be turned off and on quickly.‘‘

Ji said com­bin­ing the new and au­dited LED street­lights with a smart sys­tem would ben­e­fit ev­ery­one, along with a re­duc­tion in the city’s light pol­lu­tion.


Hangfeng Ji is an R&D man­ager in a startup com­pany fo­cus­ing in agri­cul­tural light­ing.

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