Kilowatt hour
A watt (W) is a unit of electrical power. One watt represents a current of one ampere with a voltage of one volt.
A kilowatt hour (kWh or kW h) is a unit of energy that is equivalent to 1,000 watts (1 kW) of energy being transmitted or used for one hour. The kilowatt hour is commonly used by utility companies for pricing, calculating and communicating electricity energy bills to consumers.
One kilowatt hour is equal to 3.6 megajoules – the amount of converted energy if work is done at an average rate of 1 kW per hour.
The difference between a kW and a kWh is that a kW is the energy required for an appliance to function, whereas a kWh is the amount of energy that is actually used over a period of time.
For example, a 100 W light bulb would take 10 hours to consume 1 kWh of energy. A 50 W electrical appliance that is used at a constant rate for 20 hours would use 1 kWh of energy. A 2 kW electrical appliance would use 1 kWh in 30 minutes.
To calculate the cost of running an electrical appliance, the power consumption in kWh is multiplied by the price per kWh. The unit price of electricity often varies depending on the rate of consumption, the time of day, and the location.
[edit] Related articles on Designing Buildings Wiki
- Ampere.
- Conductor.
- Domestic micro-generation.
- Electricity.
- Energy.
- Glossary of electrical terms.
- Portable Appliance Testing (PAT).
- Power.
- Power generation.
- Smart meter.
- The future of electricity in domestic buildings, a review.
- The UK’s low-carbon future is increasingly electric.
- Voltage.
- Watt.
Featured articles and news
Licensing construction; looking back to look forward
Voluntary to required contractors (licensing) schemes.
A contractor discusses the Building Safety Act
A brief to the point look at changes that have occurred.
CIOB Construction Manager of the Year award
Shortlist set to go head-to-head for prestigious industry title.
HSE simplified advice for installers of stone worktops
After company fined for repeatedly failing to protect workers.
Co-located with 10th year of UK Construction Week.
How orchards can influence planning and development.
Time for knapping, no time for napping
Decorative split stone square patterns in facades.
A practical guide to the use of flint in design and architecture.
Designing for neurodiversity: driving change for the better
Accessible inclusive design translated into reality.
RIBA detailed response to Grenfell Inquiry Phase 2 report
Briefing notes following its initial 4 September response.
Approved Document B: Fire Safety from March
Current and future changes with historical documentation.
A New Year, a new look for BSRIA
As phase 1 of the BSRIA Living Laboratory is completed.
A must-attend event for the architecture industry.
Caroline Gumble to step down as CIOB CEO in 2025
After transformative tenure take on a leadership role within the engineering sector.
RIDDOR and the provisional statistics for 2023 / 2024
Work related deaths; over 50 percent from construction and 50 percent recorded as fall from height.