The conference rooms in my office have projectors mounted on the ceilings, typical of many offices.

Ceiling-mount projector

During the day, several meetings will be scheduled in the rooms, with perhaps five to ten minutes between meetings. When the projector is turned on (or off) there is a warm up (or cool down) period that lasts a minute or two.

Assuming this process consumes energy, is it better to leave the projector on for the five to ten minutes between meetings, or turn it off and then back on?

What are the impacts in terms of total energy usage, and wear and tear on the equipment? Is there any data available on this, or has anyone tested it?

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    To answer this question you just need to now the amount of energy needed to keep it on/standby (i.e. does your projector keep it's light source on when not in use?) and during the cooldown/warmup, and fairly exactly, otherwise it's pretty much guesswork. Ideally measure this with a kWh meter directly on the projector socket. Possibly the tech specs have the number as well. Can you check that? There's also another aspect which might need considering: lifetime. Would all those ten minutes turned off increase lifetime? Or decrease, because just the act of turning on/off degrades components?
    – stijn
    Commented Jan 18, 2020 at 8:30
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    Your question calls for stats on usage so this is not quite an answer, however many of these projectors have a 'turn off on idle' timer you can set - perhaps this could be a potential solution? Setting it to 15-20 minutes idle could save 40 minutes of 'runtime' for hour-long booking windows, but still allow enough time for back-to-back meetings to change over and continue using the projector
    – Robotnik
    Commented Jan 19, 2020 at 22:20

1 Answer 1


According to my research on 'Exploring the environmental benefits of home automation'. (ref: Smart home automation _ Proud Green Home.pdf).

The many technological conveniences of the modern home put a variety of options at our fingertips. However, they can also use a great deal of energy. Forgetting to turn off the mechanical systems, lights and small appliances in your home contributes to wasted energy, and the small lights and displays on electronics - known as phantom energy - contribute to waste as well. Technology manufacturers are addressing these issues by providing new home automation products that reduce the consumption of excess energy.

Home Automation Technology Automated technology can learn your preferences or be programmed to manage the functions of your home. With smart devices that allow you to issue voice requests or adjust settings from a remote location, you can save time and money while maintaining an eco-friendly home. A central management system or hub such as Amazon’s Echo can be an invaluable addition to control a variety of elements in the smart home.

Lighting Controls Lighting controls that dim or turn off lighting can save a great deal of energy in the home. Occupancy or motion sensors can turn lights on when a room is in use, and they will turn lights off when the room is empty. Occupancy and motion sensor technology are also ideal for turning off small appliances when they are not being used. Even in the absence of smart technology, energy usage for lighting can easily be improved by using energy-efficient LED light bulbs.

Smart Power Strips Smart power strips can be programmed based on your usage patterns, and they can also be automated through the use of occupancy sensors. Using power at times when it is convenient for you or avoiding peak usage periods becomes simple. Many items that are plugged into power strips use phantom energy, and reducing this power use can result in energy savings. Even in the absence of a smart power strip, you can plug entertainment devices into one power strip that is only turned on when needed or placed on an electrical outlet timer.

Home automation and the use of smart technology also offers the benefit of tracking your energy savings, so you can realize the money savings that an energy-efficient home provides. With a variety of innovative tools to help you automate your home, you’ll enjoy convenience and cost savings while also reducing your footprint on the earth. ----

I have recently found inexpensive 'plug in devices', that are now available at WallMart, that you simply plug into a wall socket and supposedly they will reduce your total energy bill. I plan to purchase a few as a research test soon. There are also many phone apps available to test power usage. However, I plan to get the device to test energy usage and electro-magnetic radiation level of each device within your home, This meter is also available at Wallmart. However, turning on and off devices (for 15 min. wait periods) can waist more energy, thus using the standby mode may be best, if your projector is an energy star device. I noticed that a quick energy assessment asks this question: "8. Do you currently use power strips for your home electronics, such as computers, televisions, and battery chargers use about 15% of a household’s electricity and this figure increases as you continue to add more and more electronics and gadgets to your repertoire. o Power strips make it easier to turn several items off at one time to get rid of those pesky phantom loads. These are ideal for home entertainment systems and/or home computers." (ref: Energy Assessment (RECP) pg. 2 ) This assessment references a site for you to research. Perhaps you many choose to upgrade your projector and find a new one listed here on this site with new energy efficient appliances, if needed. Reference link: (www.energystar.gov) to get information on energy efficient appliances. Thanks for sharing your question, and I hope this helps. Personally, I am happy to discover that there are so many other like minded folk, who are also caring and sharing and asking questions about sustainable living! Happy Learnings...

  • Just did a search on Google and found this: "In general, turning a projector on and off repeatedly decreases the life of the bulb. But leaving it on all of the time will also decrease the life of the projector. ... As a general rule, if you expect to use your projector again within an hour, just put it in blank mode." Commented Feb 5, 2020 at 7:30
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    Welcome to Sustainable Living! I'm afraid your post doesn't really answer the question. Only the last part of your answer is more or less relevant. Your comment seems more useful, but it would help if you link to the source.
    – THelper
    Commented Feb 5, 2020 at 8:10

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