Can incandescent bulbs be banned, and can lighting be made even more efficient?
Certainly! The next step will be to replace the vast majority of halogen lamps and compact fluorescent bulbs with LEDs, which are constantly improving both energy efficiency and visual comfort. At the same time, techniques can be introduced to better collect and distribute natural light in buildings.
Lighting consumed 5.8 TWh of electricity in 2018 in Switzerland, representing 2.5% of our final energy requirements and 9% of our electricity consumption. The latter percentage has remained relatively stable over the past ten years. The services sector consumes about half of the electricity for lighting, followed by industry (26%) and residential buildings (21%). The share of lighting in the final energy consumption of households is marginal, accounting for only 1.9% of their total energy consumption and less than 10% of their electricity.
More than a century after their arrival on the market, incandescent bulbs, or filament bulbs, have been permanently banned in Switzerland and the European Union, because of their very low energy efficiency. Only 5% of the electricity they consumed was turned into visible light, the rest being lost as heat (hence the fact that they were hot). They have been gradually replaced by so-called low-energy (halogen, then fluocompact) lamps and more recently by Light Emitting Diodes, better known as LEDs.
All of these alternatives consume less electricity than incandescent bulbs, but are not equivalent. The energy efficiency of a lamp is defined as the intensity of light emitted (measured in a unit called the lumen) per watt of electrical power consumed. The good old incandescent bulb provided 10 to 15 lumens per watt (Lm/W). For the same wattage of electrical power consumed, the halogen bulb produces 15 to 20 lumens, the fluocompact lamp 40 to 70 lumens, the fluorescent 70-80 lumens, and the LED 40-130 lumens.
This ranking indicates that, in each product category, there are good and bad performers. There is still significant potential for savings in lighting by promoting the most efficient technologies, and choosing the best quality lamps in each category. The next technology to be proscribed is likely to be the halogen lamp, given its low efficiency and limited lifespan. The most economical and environmentally friendly lamps are LEDs. They offer the best energy efficiency, long life, adjustable light intensity, rapid ignition, no UV emissions, and do not contaminate the environment at the end of their life, as they do not contain polluting metals such as mercury or sodium. However, the efficiency of the LEDs depends on various factors, including colour. Warm-coloured lights that are most pleasing to the eye unfortunately have the lowest energy efficiency.
The potential for saving in lighting was estimated at 2.6 TWh, or 35% savings compared to annual consumption in 2013, and about 50% compared to current annual consumption (2018). To this could be added the potential gains for space cooling, which have not been estimated; the higher the luminous efficiency, the lower the heat losses, the less the rooms heat up and the lower the cooling needs, especially in offices in summer.
Finally, new technologies for capturing and diffusing natural light aim to considerably reduce artificial lighting during the day. The aim is to bring natural light, particularly into basements and windowless rooms, by combining mirror concentrators, skylights and light transport via fibre optics. The potential for energy savings through increased use of natural lighting is difficult to quantify. It goes without saying that an adapted architecture also improves the natural lighting in all rooms!
- Kemmler, Spillmann & Koziel (2018)
- Kemmler, A., Spillmann, T. & Koziel, S. (2018). Ex-post-analyse des schweizerischen energieverbrauchs 2000-2017 nach bestimmungsfaktoren. Office fédéral de l'énergie (OFEN).
- Kemmler, A and Koziel, S and Wüthrich, P and Notter, B and Keller, M and Jakob, M and Catenazzi, G (2017)
- Kemmler, A and Koziel, S and Wüthrich, P and Notter, B and Keller, M and Jakob, M and Catenazzi, G (2017). Analyse des schweizerischen Energieverbrauchs 2000-2016 nach Verwendungszwecken. Office fédéral de l'énergie (OFEN).
- Office fédéral de l'énergie (OFEN) (2018)
- Office fédéral de l'énergie (OFEN) (2018). Statistique suisse de l’électricité 2018. OFEN.
- Office fédéral de l'énergie (OFEN) (2019)
- Office fédéral de l'énergie (OFEN) (2019). Statistique globale de l’énergie 2018. OFEN.