Energy Use & Reduction (SQA National 5 Computing Science): Revision Note
Exam code: X816 75
Energy use and reduction
Why is energy consumption an issue?
Energy use is a major environmental concern because digital devices, networks and data centres are used constantly
Data centres alone consume an estimated 1 to 3 percent of global electricity, and demand continues to grow as more people rely on cloud storage, streaming and online services
Most electricity is still generated from fossil fuels, which leads to:
Greenhouse gas emissions
Air pollution
Water pollution
Land degradation
Disruption to wildlife and ecosystems
Reducing unnecessary energy use helps limit these environmental impacts
Reducing energy consumption
Computer systems include built-in settings that help lower power use without reducing performance
These settings cut wasted electricity across homes, schools and businesses
Monitor settings
Feature | Description |
|---|---|
Screen brightness control | Users can lower brightness to reduce power draw |
Automatic display timeout | Turns off the screen after inactivity |
Sleep for display only | Puts the monitor into a low-power state while the computer stays running |
Energy saving modes | Uses monitor pre-sets designed to minimise power usage |
Impact: Reduces energy use because the display is one of the most power-intensive components
Power down settings
Feature | Description |
|---|---|
System sleep mode | Lowers power use by pausing system activity and powering down hardware |
Automatic sleep timer | Activates sleep mode after a period of inactivity |
Hibernate mode | Saves system state to storage and shuts down almost completely |
Wake-on-activity | Allows quick resume when the user interacts with the device |
Impact: Reduces electricity consumption by cutting CPU, memory and storage power use when idle
Standby settings
Feature | Description |
|---|---|
Low-power standby state | Keeps the device ready while using much less energy |
Reduced background activity | Limits unnecessary processes while the system is idle |
Quick resume function | Wakes the device faster than a full startup |
Auto-standby timer | Moves the device into standby automatically after inactivity |
Impact: Cuts ongoing power use for devices that would otherwise run fully powered all day
Worked Example
A financial company is reviewing its environmental impact report. To reduce electricity costs and carbon footprint, the company has already implemented two policies:
1. All monitors are set to automatically reduce brightness after five minutes of inactivity
2. All computers enter standby mode after 30 minutes of non-use
Describe two other methods the company could implement to further reduce the energy consumption of its computer systems
[2]
Answer
Implementing power down settings (or low power/eco settings) to fully switch off unused systems (as opposed to standby) [1 mark]
Reducing the refresh rate of the screen [1 mark]
Closing down unused applications/windows [1 mark]
Removing external devices (e.g., USB drives, unnecessary peripherals) that draw power when not in use [1 mark]
Setting the monitor to power down when not in use (as opposed to just dimming or changing the computer to standby) [1 mark]
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