What is the difference between a kilowatt (kW) and a kilowatt-hour (kWh)?
Kilowatts (kW) measures how much electricity comes through the electrical service wires into the building. For instance, turning on more lights at the same time will cause the smart meter to read a higher number of kilowatts being used by the building at that moment. This is called “demand.” Your apartment might demand 4 kW from the grid when you are home and using appliances, and only 0.5 kW when you are away and things are turned off. A kilowatt is 1000 watts. Kilowatt-hours (kWh) measure how much electricity was consumed by the building over a period of time. For instance, in a day, your home might consume 10 kWh, and over the month it might consume 300 kWh. A kilowatt-hour is 1000 watt-hours. A 25 watt compact fluorescent light bulb (CFL) running for 40 hours consumes 1 kWh (25 watts times 40 hours is 1000 watt-hours, or 1 kWh). This is the same energy consumed by a 100 watt incandescent bulb running for only 10 hours (100 watts times 10 hours is the same 1000 watt-hours or 1 kWh).
