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
ECA Industry Awards 2024 shortlist revealed
22 leading businesses from across the electrotechnical and engineering services sector.
Government unveils Skills England strategy
Skills England to transform opportunities and drive growth.
New Government Hub for York Given Planning Green Light
For up to 2,600 civil servants, due for completion by 2028.
Construction Skills Certification Scheme cards
July update on Professionally Qualified and Academically Qualified Person Cards.
BSRIA Briefing 2024, November 22
Sustainable Futures: Redefining Retrofit for Net Zero Living.
The CLC on driving competency in the retrofit sector
Previously published roadmap on skills for net zero.
The first labour government King's speech in fifteen years
Construction industry reactions, support and some concern.
CIOB Retrofit of Buildings Technical Information Sheet
What retrofit is, the approach to be taken and processes to be followed.
Adapting Historic Buildings for Energy and Carbon Efficiency
Historic England advice note 18, free download published.
10 retrofit projects revisited 10 years after completion.
Information orders, building liability orders and SPVs
Key BSA terms and how they impact special purpose vehicles.
Listed despite problems with its design.
Zen and the art of cycling exploration.
Design Council Homes Taskforce launched
To support government 1.5 million homes target within UK climate commitments.