In a recent report from California Energy Commission (CEC), it has been recommended to consider and promote hibernate and shutdown actions compared to sleep action. It has been suggested to achieve this goal by presenting time-to-hibernate and time-to-shutdown along with the time-to-sleep to the user in order to nudge them toward a more comfortable decision to pursue hibernating or shutting down their computer (page 5 of the report accessible at: http://www.energy.ca.gov/2014publications/CEC-500-2014-093/CEC-500-2014-093.pdf).
This shows an implicit assumption that the energy consumption of the shut-down state is less than that of the sleep state. Although it is practically true, this assumption ignores the impacts of 'transitional' states that are required to transfer the computer from the power-on state to the shut-down state. These impacts could be much higher than the benefits of the overall change. For example, hard drives and other components may perform intense operations during these transitional states in order to prepare the system to hibernate or shut down. These operations not only would consume energy, they also may result in lowering the remaining life time of those components, especially the hard drives. The question is that what is the optimal time interval of inactivity that beyond that a shutdown or hibernate action would be more beneficial compared to an sleep action.
It seems answering to this question would require some analysis of the life cycle of various components, especially their nonlinear behavior against various forms of the transitional states.
https://www.linkedin.com/pulse/article/20141104033724-60666930-is-energy-consumption-the-sole-parameter-to-decide-between-sleep-or-shutdown-actions-for-a-better-good
Dear Reza,
Your question is very interesting and you presented it in a very clear way such that i feel you included some answer to it. Your question is rather a point of research on the decision criteria on the the operational mode of an electronic equipment especially the computers to save energy consumption. The equipment has three states, namely operating on, sleep on, and off. The energy consumption in operating mode is the highest and the sleep mode is minimum and in the off state it is zero. The equipment is held in sleep mode to in a standby mode where it i ready to run in a short time. In the off state, the device needs long start and off time in addition to the switching action that can shorten the life time of the devices addition to the more energy consumption required for these actions.
So, the decision between the sleep mode and the shut down is not easy and needs to develop accurate and precise criterion to judge on this action. Yes, it is clear that the sleep mode interval is the parameter that may be compromised to make the decision.
This period may be determined based on the following factors:
- The amount of energy saving
- The effect of switching actions on the lifetime of the device.
-The time spent in the on and off times.
Accordingly, i would propose to reduce the on end off times of the computers as they are really sludge. I asked myself this question many times!
greeting for you for invoking this question
Dear Abdelhalim,
Thank you for your insights. I would like to see some suggestions or 'rules' that users could practically follow. Such suggestions could be integrated in smart interfaces in order to provide an appealing quality of experience to users. Examples of such suggestions could be:
i) If you leave the office for lunch hour, shut down/hibernate your station,
ii) If you leave your station to make a coffee, put your station in sleep, and so on.
As you mentioned, all these depends on research on the behavior of components in the transitional states. I would be happy if you or anybody could contribute with their research results if available.
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