Posted on: 28 - 2 - 2020

How is the industry using maintenance factors?

We discovered how the wider industry are calculating their maintenance factors, how LED lumen maintenance data influence product selections - and more.

At the end of 2019 we surveyed electrical engineers and lighting designers throughout New Zealand about how they apply maintenance factors. The purpose of this was to share our learnings with the market so people can see what industry peers are doing. We had a total of 78 qualified respondents participate which represents 33% of the requests we sent.

We found out how the industry are calculating maintenance factors, whether they are using standardised methods and principles and more.

All percentage results have been rounded to the nearest whole number using Swedish rounding.

68% of respondents design interior lighting either all the time or frequently, with the remaining 32% designing lighting sometimes. 15% identified as lighting designers, 82% as electrical engineers with the remaining few identified as electrical designers or technicians. These results qualify the respondents as having applicable experience to answer the survey, providing a valuable set of results.



Question: When approaching an interior lighting design, how are you most likely to calculate maintenance factors?

53% of the market is using the tables in AS/NZS1680.4.17 along with luminaire manufacturer data. Interestingly, 13% of the market responded with Other and through interpreting the explanations, half of these designers will reference standards in various ways and depending on the lighting application, showing the greatest proportion of the market is calculating their maintenance factor using standards.

20.5% of the market use factors for the room and luminaire maintenance but treat all LED luminaires the same. Only 14% use the same maintenance factor for all spaces and all LED luminaires.

Question: Does LED lumen maintenance data from manufacturers influence your product selection?

LED lumen maintenance data appears to be something important to the market with only 4% of the market answering Never. At the other end of the scale, only 18% of the market use LED lumen maintenance data All the time to influence their product selection. The majority of the market (78%) answered with either Frequently or Sometimes.

Question: For typical interior lighting, how important is avoiding dust contamination in LED luminaires?

These results show the importance for avoiding dust contamination in LED luminaires with all respondents placing some level of importance on it. Of those results 83% feel it’s either quite important or essential, with only 17% finding it’s not very important.

Question: When evaluating a luminaire, with all other elements being equal, which fixture would you choose?

Here the market is showing greater support for better lumen maintenance values at shorter lifetimes with 74% of people preferring L90 @ 50,000hours. We recognise this decision could often be dependent on the project or application requirements.

Question: LED manufacturers often state an L number and B number for lumen maintenance (e.g. L80 B10) how do you use the B number in your lighting calculation?

We recognise this is a question on a complex topic. Here, half the market (51%) is simply using the L number only in their calculation but are using the B number to rule products in or out of their design. 13% of the market do not know enough about the B value to use it and 24% know what it means but choose not to factor it into their assessment or calculation. Only 12% of respondents alter their lumen depreciation factor based on the B value.



The majority of people who design interior lighting in their daily work utilise defined engineering principles & standardised methods to get a predictable outcome for their clients. Accurate information from suppliers is paramount as these principles and methods require more information from suppliers than ever before.


A huge thank you to all the people who took the time to respond to this survey! Without your responses we could not collate this kind of information and present local data back to the market. This is our first survey, and we aim to run more like it and provide real value for lighting designers & electrical engineers in New Zealand.  

Thank you also to all of the Energylight team for their support and hard work to develop the content, wording and execution of the survey.


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