Think of how we use the lights in our homes now and in the past. Today we switch on the hallway light to go to the kitchen (if it wasn’t already on), then switch on the kitchen light and possibly other lights, illuminating a large part of the home. This takes a lot of energy compared with the much more efficient means people used more than a century ago: oil lamps and candles. It also illustrates how, while the technology we choose is important, the way we use it can make a much greater difference in how efficient it is.
Most past energy sources were sustainable, but not all. Over the centuries oil and gas for lighting were obtained from a number of sources including fossil fuels (oil and gas distilled from coal), animal fat (including whale oil), and some forest and agricultural byproducts (including olive oil), but the average person used the less expensive candle most of the time. Light also came from fireplaces, which had to be kept burning during the cold, dark months of the year anyway. In the late 19th century we developed and learned to depend on petroleum fuels which provided huge amounts of energy at extremely low cost. Since then we have installed so much electric lighting that the earth has become a glowing ball of lights when seen from space. We can’t keep lighting up the universe in this way, however. There isn’t enough fuel to live the way we do much longer, and eventually we will have only renewable energy sources. Solutions to this problem include conservation, and I will show that the concept of personal lighting – illuminating only those specific things you need to see – can enable savings at or below sustainable levels, and at levels that make recharging by solar cells an attractive possibility: almost all of the lighting we use in our homes and workplaces could be obtained “off the grid”.
Personal lighting may eclipse room lighting in the future. In the future, instead of turning on all those lights to go to the kitchen at night, we may pick up a small headlight-flashlight from a charging stand and put it on our heads, then turn it on with just enough power to see where we are going as we make our way to the kitchen. Once in the kitchen we may turn up the brightness of our headlight for a minute or two as we complete what we went to do, and then switch it back to a lower power level for the walk back. When we go to bed – I almost said “turn off the lights and go to bed” which just shows just how deeply invested we are in our current, more wasteful ways – we will take off the headlight and put it back on its charging stand where the light of the next day will recharge it via a solar panel. We’ll probably each have several of these small but highly efficient lights in different places around the house and in our pockets, and we will use them for almost everything after dark – reading books or doing crafts, for example. Homes will be mostly dark at night except for the faint lights of the headlights worn by those inside (along with the lights of video and computer displays). The savings can be great as I will show.
I have been experimenting with the personal lighting concept. I recently purchased one of the new LED headlights (Energizer TrailFinder HD33A3CE Triple Beam Headlight, $18-25) and, while it is not solar-powered or rechargeable, it is extremely efficient, convenient, and effective. It has three LED‘s on it, one red, one green, and one white, and runs on three triple-A sized batteries. The packaging says that, using the white LED on full brightness, the batteries will last about four hours. The white LED on reduced brightness will allow the light to work for over seven hours, but the green LED will operate for over thirty hours and the red LED will operate for over eighty hours. The red LED is the dimmest but is still sufficient for walking around the house at night. The green LED is brighter and permits more activity than just finding one’s way around, but is probably too dim for reading. The white LED on the low setting is more than bright enough for reading, and probably bright enough for walking outdoors at night, while the white LED on full brightness can easily illuminate detailed crafts work, for example, and give enough light for jogging outdoors in the dark of night. One of the key benefits of a headlight is that the light is focused only where you are looking and no light is wasted in illuminating things you’re not looking at.
What’s the cost difference between using a headlight and using room lighting? There will still be an occasional need for room lighting but we won’t use it much. My headlight may not permit good viewing of art, for instance, and room lighting might be preferable for gatherings of people, but such uses will be limited. Today’s reasonably sized living room may require 200 Watts to be fully illuminated with incandescent lighting. The same room lit with compact fluorescent bulbs would require only about 25 Watts. With LED lighting it may require 15 Watts to achieve the same results in the future. A headlight, however, will illuminate what you want to see using only 1 Watt, so the cost of reading for an hour in the evening works out like this (all figures are estimates):
Incandescent lighting 200 W or 0.2 kilowatt-hours, 1 hour
Compact fluorescent lights 25 W or .025 kW hours “ “ 1/8th of incandescent
LED lighting 15 W or .015 kW hours “ “ 1/13th of incandescent
LED headlight 1 W or .001 kW hours “ “ 1/200th of incandescent
The principle is clear: conservation saves money. As is often the case, major savings can be accomplished with minimal effort. There are practical considerations that may change these figures somewhat. For example, reading with a single light source and no background lighting for periods of time may cause eye strain. Still, if we start thinking and adapting now we can make those future transitions to using less energy much easier, for us and our descendants.
The simple solutions are often already available, and it is only people’s understanding that needs to change. I believe my example illustrates a way in which electric lighting costs can be slashed to sustainable levels not only by employing more efficient technology but by using it intelligently. While people might not find the idea attractive today, I believe it is inevitable that we will need to reduce our energy use tremendously in the next few decades, and this is only one of many changes we will need to make.
We don’t really have a choice: a decline in energy availability is highly probable in the next few decades. Remember that, at any level of consumption above what we can supply from solar, wind, and other renewable sources, we are not in a sustainable situation, and this will cause problems. I see living with headlamps as a simple and available way to greatly reduce the energy we use in lighting, and fully expect that I and my children and grandchildren will be using headlights in the future as I described. In summary, though – while we can save a lot of energy using new technologies, we can save a lot more by using those technologies intelligently.
As always, I welcome your comments. Thanks for reading — Tim