Introduction to Lighting: Comparing Technologies

Lighting is something that often goes unappreciated and unnoticed (unless it’s not working well).   But obviously light plays a fundamental role in our lives and considering that we now spend more than 90% of our time indoors, indoor lighting is pretty important.  Now consider that more than 30% of a hospital’s electricity goes towards lighting in our climate zone and it becomes even more important.  To help shed some light on the subject (unintentional pun) I’m going to be writing a multi-part series talking about lighting and the work we’re doing here at UHN.  There are some really interesting projects and we’ll be providing you the data to judge.  I’ll also bring you first hand information directly from our resident light expert and TGH electrician Henry Gomolka.   But first, a primer on lighting.


Photo: NASA – The Sun at different wavelengths

There are four main technologies behind space lighting today:  Incandescent, High Intensity Discharge, Fluorescent/Induction, and LEDs.  In essence, these technologies convert electrons into photons through the use of different materials.  Incandescent lights use hot metal (tungsten) filaments, HIDs create superheated plasma, fluorescents use a mercury vapour and a phosphor coating, and LEDs are made of semiconductor materials.  To elaborate for a moment and let you marvel at the science behind 140 year old technology consider this, incandescent lamps use an electric current to excite the atoms of the filament by heating them up.  This causes the electrons to jump to a higher energy state a.k.a. orbit or shell.  This is a very unstable state for the electrons and they rapidly drop back to a lower energy state, emitting the excess energy as photons (light).  But if the filament were exposed in air, it would quickly burn up, so it is surrounded by an inert noble gas within the glass container.

The takeaway is that it’s no small feat of science trying to mimic the sun.


Lighting terminology:

There are many different terms but a few of the basic ones are:

  • Lumens [lm] – the amount of visible light emitted
  • Efficacy [lm/W] – the amount of light in lumens produced per watt of power input (similar to efficiency)

Lumens and efficacy allows us to compare different lighting technologies and different fixtures.

  • Lux [lm/m2] – the light intensity at a given plane (e.g. desk height)
  • Lighting Power Density [W/ m2] – is a measure of how much lighting power is installed

Lux and LPD allow us to compare a lighting systems design.  But note that despite the units, lux isn’t just the total lumens divided by the floor area.  This is because light isn’t evenly distributed and different materials absorb and reflect different amounts of light.  The best way to determine lux is through a computer generated photometric plot.  There are also design standards to follow for lux and LPD.

Comparing Lighting Technologies:

Nearly 140 years ago we started lighting with incandescent bulbs, we then added HIDs and fluorescent tubes, and more recently we’ve transitioned to CFLs.  But now LED technology is threatening to replace them all.  Before I post on UHNs projects I wanted to get your feet wet with an example closer to home.  I’ve taken a standard 60W (800lumen) incandescent residential style bulb (A19) in a warm colour temperature and compared its energy efficient equivalents.

Standard 60W Equivalent Bulbs













If you thought lights don’t last long now, consider that in 1879 a lifespan of 3.5 hours was considered a breakthrough achievement (Edison later used a carbonized bamboo filament that could last 600 hours).  Today incandescent lamps don’t last much longer but there are other options available.  Actually it’s getting to the point where you will pass these lights down to your children (operating 4 hours a day the LED bulb below will last for 17 years, or 34 years at 2 hours a day).

60W Equivalent Rated Life




Rated Life* (hours)




Days on 24 hours




Days on 4 hours




*Note that the rated life can be misleading, for incandescent and CFLs it means that 50% of the bulbs will fail before the rated time.  For LEDs it means that the light output will depreciate by 20 or 30%.  LEDs don’t burn out, they fade away.


So LEDs last longer but what about ‘efficiency’.  CFLs were a great stopgap technology, but they’ve about reached their technological limit.  They also come with the extra baggage of containing mercury, which is highly toxic and readily enters the food chain.  With LEDs anything I write will shortly be outdated and they’re already leading the way.  Our efficacy comparison below shows LEDs as 30% better than CFLs and this is just the beginning.

60W Equivalent Efficacy
















In some applications LEDs have another benefit, in that they  are directional in nature.  Other technologies shoot light in all directions, which then must be reflected to where you want it (think of a pot light with the fixture recessed up in the ceiling).  There are a lot of losses as a result and this is one of the reasons why people perceive LEDs as brighter.   In our UHN tests we measure the lux level to compare; in the next article I’ll show you the measured effect.

Lifecycle cost

For lifecycle costs I’ve used a common multiple of 50,000 hours to make the comparison.  In a residential application, with the light on a few hours a day, this is a very long time.  So keep in mind that you need to use the bulb for its full life to get the full value out of it.

60W Equivalent Lifecycle Cost





Bulbs used (50,000hrs)




Cost per bulb




Total Cost for Bulbs













Energy Cost (@$0.12/kWh)





Total Cost  for 50,000hrs




So we see that residential style LEDs are cost competitive which is great, but due to the higher upfront costs, it may be still be hard to justify LED purchases for the home.

But I’ve actually missed something, I didn’t include disposal costs in my lifecycle costing.  This is an important consideration because CFLs aren’t allowed in your household garbage or recycling (stated by the City of Toronto).  To dispose of your CFLs properly you have to find a Hazardous Waste drop off, a Community Environment Day, or an IKEA store (links provided at the end of this article).   So if you don’t want to worry about disposal for 17 years and want to save money in the process, definitely consider LEDs.

I can tell you that with commercial lighting, the incentive to move to LEDs is much greater and even more apparent.  At UHN we have increased lighting requirements, longer running hours, maintenance costs, disposal costs, and more.  We also have areas where you don’t want to have to change a light bulb ever (e.g. An atrium ceiling 4 stories above the ground).  A light that will last for 10 years with limited maintenance and less energy benefits everyone.  In the next article I’ll show you some of the dramatic UHN examples.

Fluorescent Disposal

Lighting Information

9 thoughts on “Introduction to Lighting: Comparing Technologies

  1. I’ve been using CFLs for over a decade now – mostly cheap ones from IKEA at that – and I’ve never had any of the problems others report with color temperature or short lifespans. Last week I just replaced the first CFL to die since I moved to this apartment 4 years(!) ago.I’m also not the least bit worried about the trace amount of mercury modern CFL’s contain. It’s elemental mercury, which is much less dangerous than the organic mercury that comes from burning coal, and which contaminates so much seafood these days. So long as you don’t snort one if it breaks, you’ll be fine. And they burn so much less power, even if you broke every one you used, you’d still be pumping less mercury into the environment than if you used incandescents.That having been said, the LED bulbs are very promising, although what I’m really looking forward to are entirely new lighting fixtures that don’t even rely on the traditional “lamp” form-factor, which LEDs are going to make possible.


    • Thanks for the comment! I agree that CFLs have been great to help us reduce our energy use and we would be worse off without them. In residential applications they can last for many years. Further, when Ontario’s power mix had more coal, they also resulted in a net mercury emissions reduction (as you noted). However, I do want to correct you on one point. The elemental mercury (both liquid and vapour) contained in CFLs is a concern. Microorganisms in the water and soil can convert elemental and inorganic mercury into its organic form methymercury, which bioaccumulates and moves up the food chain. The liquid elementary mercury emits mercury vapour, which in a landfill is released just as methane is. This mercury vapour travels through the air, perhaps ending up in our waterways. Additionally, there have been some excellent studies showing that landfills leak, which could result in contaminated groundwater. Usually there is a delay in the leaks as the liner materials break down, so we won’t know about the effect right away / until it’s too late. Also, as the fuel sources change (according to Gridwatch today’s fuel mix in Ontario is 0.8% coal) the CFLs can no longer be seen as a net benefit in terms of mercury emissions, since we aren’t offsetting mercury production from coal power plants. The source emissions during CFL manufacturing is also a concern. Now considering the rising levels or mercury in our oceans, population, and the health risks (especially to pregnant women), I would say we should do whatever we can to reduce mercury emissions. Hopefully LEDs render this discussion moot, but in the interim, I encourage everyone to dispose of their bulbs properly, and not in a landfill.

      – Chad


      • Thanks Chad…that’s great information. To follow up on proper disposal of CFLs and other fluorescent light bulbs, check your municipality’s website on Household Hazardous Waste. For the City of Toronto, it’s and they can let you know where the closest drop-off depot is. Also, many stores have started a “take-back” program for things like this. Ask your nearest home-improvement store (where you likely bought the bulb in the first place). That should help us all keep mercury out of landfill (and land, air and waterways).



  2. Thanks for the information Chad, I agree that LED light bulbs are becoming increasingly popular with designers and consumers of green technology, as they use less electricity, last longer, and emit more light on a pound-for-pound basis than traditional incandescent bulbs.
    But on the other hand induction lights are safer, more efficient, and less expensive than LEDs. Although LED lighting may be deemed the “light of the future” it still has a great deal of research that is necessary before becoming the go-to light for every need.


    • Hi Jack, thanks for your comments. We’ve actually reviewed induction lights for some of our applications and there are a few reasons we chose to go with LEDs:

      – Lifespans for induction lights are rated based on 50% failing before that time. Whereas LEDs don’t actually fail, then just slowly dim. For a parkade we’re looking at LED lights with 100,000 hours and a lumen depreciation factor of 0.88 (meaning we have 88% of the initial lamp lumens at 100,000 hours). Granted that number is extrapolated data from a year or so of testing, since they haven’t been around for 10 years, but their warranty backs up their data.
      – Induction lights contain mercury, LEDs do not.
      – Induction lights throw light in all directions and therefore need reflectors to focus light where you want it. This wastes energy. LEDs are directional and can provide light where you want it, without wasting it in uplighting or through reflectors.
      – LEDs product more light per watt. The same LED parkade fixture produces > 90lumens/watt, while a comparable induction light products ~80lumens/watt.
      – Because of the higher lumens/watt and more directed light, we are able to use less energy with LEDs than we would with induction lighting


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