Which light source is more environmentally friendly: an LED or an incandescent bulb? Given the toxicity of the materials contained in the former, and the difficulty of recycling some of its complex elements, it turns out that less impact on the environment may have the second of these two sources of light. Especially if the new kind of incandescent bulb designed by John Routledge would be put into production.

I interviewed John Routledge, a graduate from Innovation Design Engineering course conducted at RCA in London, at the Global Grad Show that was one of the top events organised within the Dubai Design Week 2016. The transcription of this interview has been edited for space and clarity. To watch the original conversation conducted in Dubai, press play on the video embedded below. What are you presenting at Global Grad Show in Dubai?
John Routledge: The project that I’m exhibiting here is called ”Recandescent”. It is a prototype of a new type of a light bulb that is more environmentally friendly than LEDs.

Do you suggest that LEDs are not very eco-friendly?
The starting point of my project was the realisation that LEDs are not so environmentally friendly as I thought they were. LEDs are very good in the use phase, as they don’t consume a lot of electricity, which means there is less CO2 emission from their use [comparing to traditional incandescent light bulbs – ed.]. But when a LED bulb stops working, it becomes a big problem. They can’t be recycled, and they contain several toxic materials.

What toxic materials do LEDs contain?
Toxic materials they contain include, among others, lead, arsenic, and BPA. These could leach out of an LED bulb into the environment and, potentially, poison us. Most of the rest of materials are silicon, copper, and stuff like that. Believe me or not, but most of LEDs also contain a small amount of sapphire in the middle of them. Literally, there is a precious gemstone inside an LED.

LEDs contain metals like copper and zinc, but these are fused together in such a way that they cannot be retrieved. In fact, there is currently no effective way of recycling LEDs.

As LEDs are not very eco-friendly, why did they go mainstream?
Number one, there is no better alternative for them right now. They are literally the best option we have today, even though they are not perfect. Number two, LED is a relatively new technology. I don’t think that anyone fully appreciates the damage they will cause in the not too distant future.

A similar example is a compact fluorescent light bulb, the original energy saving light bulb back in the eighties and the nineties. About ten years after they went on sale, people started to realise that the mercury in them is causing a big environmental issue. Now, there are regulations around compact fluorescent lighting, and they can’t be disposed of in a normal waste disposer. I think a similar thing will happen to LEDs in ten years time when people will be more aware that there is an issue.

What does happen with a burnt out LED bulb today?
Obviously, I can’t speak for the entire world, but when an LED lamp is broken down in the UK, you have to bring it to a special recycling centre, as it is a specific kind of waste called WEEE, that stands for Waste of Electrical and Electronic Equipment.

Then the bulb is sent off to a special process to be broken down into its constituent components. The outer casing is brought off to recycle metals. The internal electronic components are scraped off of the chip board. The chip board itself is chopped up and melted down into a lower-grade silicon. The rest of bulb components, including the LEDs, are chopped off and simply sent to a landfill, as there is nothing else you can do with them.

Can you still find any advantage of LEDs?
At the moment, the majority of world’s electricity is produced using non-renewable resources. It means the lesser amount of energy you have to produce, the better it is for the environment. The low energy consumption is the main positive of LEDs. That’s why I’m not saying we should stop using LEDs. They are the best light source we have right now. But the point of my project is the challenge that we need to be better than this.

We produce about 2 billion LEDs a year. They are really good now, but we are creating another problem for the future.

There is a paradox, that if we were using energy that in 100% comes from renewable sources, so there wouldn’t be CO2 emissions related to its production process, the incandescent light bulb would be the most environmentally friendly bulb. That’s because it has a very low input of energy, it is very easy to produce, and it is made of simple, easily recycled materials: it is made of glass, tungsten, and aluminium. All of those can be recycled readily right now.

Moreover, a paper came out this year in the journal ”Nature Nanotechnology” by a group of academics from MIT. They have invented a Hot Mirror, the new optical device that acts to reflect the heat but not to reflect the visible light. They demonstrated in one of their experiments that putting Hot Mirrors around the incandescent filament could boost its energy efficiency from 5 to 40%. To put it info a context, an LED is about 20% efficient.


What was the basic assumption when you were designing the bulb?
I tried to make something that is as good as LEDs in use, or even better, but something that doesn’t have the negative consequences when is done.

Heavily influenced by cradle-to-cradle design thinking, I was looking at ways of designing the lightbulbs that could be used in a circular economy model. The main design element for that was the creation of a modular lightbulb, where each component is relatively simple and is made of one or two materials. That means it is much easier to separate and to get pure material out at the end.


The transparent part of the prototype bulb was 3D printed. This is just a demonstrator. In reality, it would be made of glass. This is a beautification cover to give the appearance of something similar to a normal light bulb. Customers will not buy any crazy sci-fi lightbulbs that don’t fit with the lamps they already have at home.


The component in the middle that refers to the light source is the most important part of the project. Two surfaces in the front and back would be Hot Mirrors, and they would be removable from the light source.


The idea is that the filament could be taken out when is broken, and then would be melted down, re-extruded into a new filament, re-inserted, re-gassed and put back into Hot Mirrors and sealed. My project is based on reusing the Hot Mirrors over and over again, rather than buying new ones, as well as reusing the same tungsten material to make filaments.


This component here refers to a stem. This is more an aesthetic component than anything else. It’s designed to hold the source at the right height to replicate the light output that you would get from a normal incandescent light bulb.


The last component is the base that would be screwed into a normal light fitting. That is a bit of pressed aluminium with a small amount of glass in the bottom. Both sections could be unscrewed and you could recycle each part independently.

What is the lifespan of the filament?
The lifespan of the filament is about 4000-5000 hours. In a domestic saying, that equates to about four years of use.

Then, the recycling and refurbishing process of the filament must be made by the manufacturer, right?
Indeed. Because you need to maintain a very pure argon atmosphere inside to make the filament work, this could be made only at the factory. It means that there must be incentives for clients to return the broken filament to the factory.

My proposal is a service model. You would never own the main component of the lightbulb, but you would rent it from the light company. When it breaks, they would send you a new one, and you would send them the old one back. This would stimulate the behaviour changes required to move from a ”take, make, dispose” concept based on the linear economy, to the reuse concept that links to the circular economy.


What in your opinion will change in the design industry within the next decade?
I think that cradle-to-cradle design principles and circular economy are going to be big parts of our future. It’s taking a long time to gain traction, but I think it’s important to start thinking about design and products more holistically.

We can’t just make something, and let someone else worry about how to get rid of it. It is our responsibility as designers to consider these things, and to make sure that we aren’t unknowingly creating a bigger problem for someone else in the future.


To learn more about the impact of different kinds of light sources on the environment, please study the document ”Potential environmental impacts from the metals in incandescents, CFL and LED Bulbs” by Seong-Rim Lim et al., published in „Environmental Science and Technology” 47 (2013), p. 1040, that John Routledge refers to.


If you have any questions regarding the ”Recandescent” project, please do not hesitate to send an email directly to John Routledge at

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