Energy Glossary

British Thermal Unit (BTU) – defined as the amount of heat required to raise the temperature of 1 lb of liquid water by 1 °F at a constant pressure of one atmosphere.  MMBtu represents one million BTU. This is a common measurement unit of several types of energy.

Carbon footprint – the total set of greenhouse gas (GHG) emissions caused by an organization, event, product, or person.

Carbon offsetting – reducing a carbon footprint.

Consumption vs Demand – kWh vs kW – Consumption is the total amount of energy used during a period of time (kWh); demand is the rate of that consumption usually measured in 15 or 30 min intervals. (Automobile analogy to understand how demand and consumption relate: the car’s speedometer is like the demand and the odometer is like the consumption.)

Capacity (kW) – how much energy the system must be able to generate to meet the instantaneous load.

Degree days – Used in the energy industry as a representation of outside temperatures and how it relates to energy consumption.

Heating degree days (HDD) – measure of how much (in degrees) and for how long (in days) outside temperature was lower than a specific base temperature.

Cooling degree days (CDD) – measure how much (in degrees) and for how long (in days) outside temperature was higher than a specific base temperature.

Demand Response – Mechanism to manage customer consumption of electricity in response to supply conditions.

Heat Rate – Used to calculate how efficiently a generator uses heat energy. It is expressed as the number of BTUs of heat required to produce a kilowatt-hour of energy. Power / Natural gas = Market Implied Heat Rate.

Hedging – a position established in one market in an attempt to offset exposure to price changes or fluctuations with the goal to minimize risk.

kW, kWh – 1 kilowatt or 1 kilowatt hour of electricity.

Load Factor – average consumption divided by the peak power over a period of time.

RECs – Renewable Energy Credits – are tradable, non-tangible energy commodities in the U.S. that represent proof that 1 MWh of electricity was generated from an eligible renewable energy resource.