Glossary

The abbreviations and terms you meet in the wizard, the results and this library, in alphabetical order. Each entry is short. Where an article explains the idea properly, the entry links to it.

Abbreviations

Term	Meaning
A7/W35	A test point for a heat pump: outdoor air (A) at 7 °C, water (W) leaving the heat pump at 35 °C. A35/W18 is the cooling equivalent. See COP and SCOP.
AC	Air conditioning. In EnergyFlow, split units that cool the room air.
COP	Coefficient of performance: heat delivered divided by the electricity used, at one moment. See COP and SCOP.
DHW	Domestic hot water, the hot water for showers, baths and taps. See hot water.
EER	Energy efficiency ratio: heat removed in cooling divided by the electricity used, at one moment. See EER and SEER.
EMS	Energy management system, the controller that decides where electricity goes each hour: house, battery, car or grid. See what an energy management system changes.
EPEX	The European power exchange whose day-ahead auction sets the hourly wholesale prices behind a dynamic tariff.
ERA5	A reanalysis of past weather from ECMWF, the source of the real weather years. See weather.
EV	Electric vehicle, an electric car.
kWh	Kilowatt-hour, a quantity of energy. Your electricity bill counts kWh.
kW	Kilowatt, a rate of power. A 10 kW heat pump can deliver 10 kWh of heat in one hour at full output.
kWp	Kilowatt-peak, the rated output of solar panels under standard test conditions. “A 6 kWp array” on a quote. See PV size and roof directions.
MVHR	Mechanical ventilation with heat recovery: two fans and a heat exchanger that warm incoming fresh air with the heat of the outgoing stale air. See ventilation.
n50	Airtightness: how many times per hour the air in the house is replaced when a blower-door test holds it at 50 Pa. Lower is tighter.
P4P	Four-pipe heat pump. It heats and cools at the same time, and moves the heat it takes out of the house during cooling into the hot circuit, for example the pool or the hot water.
PV	Photovoltaic, solar panels that make electricity.
SCOP	Seasonal coefficient of performance, the COP averaged over a heating season under standard conditions. See COP and SCOP.
SEER	Seasonal energy efficiency ratio, the EER averaged over a cooling season. See EER and SEER.
TMY	Typical meteorological year, a year assembled from the most ordinary months of many real years. See weather.
V2H	Vehicle-to-home: a parked electric car powers the house through a bidirectional charger. See the methodology article.

Terms

Term	Meaning
Backup heater	An electric heater in the heating circuit that helps the heat pump on the coldest days. See the backup heater.
Day-ahead price	The wholesale price for each hour of tomorrow, set in an auction the day before.
Dew point	The temperature at which moisture in the air condenses on a cold surface. It limits how cold a cooling floor may get. See floor cooling and condensation.
Dynamic tariff	An electricity price that changes every hour with the wholesale market, instead of one fixed price.
Envelope	The shell of the house: walls, roof, floor and windows.
g-value	The share of the sun’s heat that glass lets through.
Round-trip efficiency	The share of the energy put into a battery that comes back out.
Self-consumption	The share of your solar production used in the house, directly or through a battery. See self-consumption and self-sufficiency.
Self-sufficiency	The share of your consumption covered by your own solar production. See self-consumption and self-sufficiency.
Setpoint	The temperature the heating or cooling tries to hold.
State of charge	How full a battery is, as a share of its usable capacity.
Thermal mass	The heat the materials of a house can store. See thermal mass.
Thermal zone	A part of the house the model treats as one body of air with one temperature. In EnergyFlow each floor is a zone. See the house model.
U-value	How much heat passes through one square metre of a wall, roof, floor or window for each degree of difference between inside and outside. Lower is better insulated.
Weather compensation	A control that lowers the heating water temperature on milder days, so the heat pump works more efficiently. See floor heating, radiators and weather compensation.