Lesson Notes By Weeks and Term v4 - SHS 2
ENERGY EFFICIENCY AND CONSERVATION
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ENERGY EFFICIENCY AND CONSERVATION
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Engineering
Class: SHS 2
Term: 2nd Term
Week: 17
Grade code: 2.2.3.LI.3
Strand code: 2
Sub-strand code: 3
Content standard code: 2.2.3.CS.1
Indicator code: 2.2.3.LI.3
Theme: ENERGY SYSTEMS
Subtheme: ENERGY EFFICIENCY AND CONSERVATION
This page supports the lesson note with a companion video and a short classroom-ready summary.
For class groups and homework, share this lesson page so learners also get the summary, objectives, and full lesson context.
In Ghana, we all experience the cost of electricity, whether through our prepaid meters running out ("prepaid finish") or the monthly ECG bills. We have also faced periods of power rationing, popularly known as "dumsor." Understanding how to use our electrical appliances wisely is not just about saving money for our families; it's also about reducing the strain on our national power grid and protecting our environment. This lesson will equip you with practical skills to become an "energy champion" in your home and school, helping everyone use electricity more intelligently.
This section breaks down the core ideas you need to master. A. Energy Efficiency vs. Energy Conservation
These two terms are often used interchangeably, but they mean different things. Energy Conservation: This is about reducing energy consumption through behaviour change. It's about using less energy. Example: Switching off the lights when you leave a room. You are conserving energy by choosing not to use it. Analogy: If you want to save petrol, you can choose to walk or take a "trotro" instead of driving your car. You are conserving fuel by reducing your car usage. Energy Efficiency: This is about using less energy to perform the same task. It involves using technology that is designed to waste less energy. Example: Replacing an old incandescent bulb (which produces a lot of heat) with an LED bulb. Both light up the room, but the LED uses far less electricity to produce the same amount of light. Analogy: If you want to save petrol, you can replace your old car with a new, hybrid car that travels more kilometres on the same litre of fuel. You are still driving the same distance, but more efficiently.
In summary: Conservation is about *behaviour* (doing less of something), while efficiency is about *technology* (doing the same thing with less). To be truly effective, we need both. B. Understanding Energy Consumption (Kilowatt-hour, kWh)
Electricity bills are calculated based on how much energy you use. The unit of energy is the Kilowatt-hour (kWh). Power (Watts, W): This is the rate at which an appliance uses energy. You can find it on a label on the back or bottom of the appliance. 1000 Watts = 1 Kilowatt (kW). Energy (kWh): This is the power an appliance uses over a period of time.