721 hourly rows · MID-class heat meter present: no
2.80efficiency (COP) over 721 hours, from the heat meter better than 5% of the metered fleet in January 2026
Electricity used
316 kWh
Heat delivered
883 kWh (heat meter)
Estimate without heat meter
flow sensor 2.65 · temperature model 3.50
Mean outdoor temperature
10.8 °C · 214 space-heating hours · cooling 0 kWh removed (0 kWh electricity), kept out of the COP
Flow temperature at 0 °C outside
51.7 °C (curve slope -1.02 per K)
Flow − return while heating
3.6 K
House needs at −3 °C
5.8 kW (unit rated 12 kW) · fit r² 0.02
Hot water
no hot-water flag in data
seriousWinter efficiency 2.8 is below the 3.0 floor used for German subsidies
Ask the installer for a commissioning check; the causes are usually flow temperature, hot water settings, or sizing, all listed below.
seriousFlow temperature runs at about 51.7 °C when it is 0 °C outside
Lower the heating curve in steps of 2 °C and check rooms still reach target. Every 1 °C lower typically saves 2–3% electricity.
infoUnit is rated 12 kW but the house needs about 5.8 kW at −3 °C
Oversizing causes cycling in mild weather. Cannot be fixed cheaply now, but the curve and minimum run time can limit the damage.
noteOwner’s note on the source site: “Outside temperature error”
valueReaching the fleet’s January median (3.69) would have saved about £19 in this window at 0.25 GBP/kWh. An estimate, not a promise.
Day by day
electricity per daydaily COP3.0 floor
Daily COP needs a heat meter; days without one show electricity only.
The installed heating curve
one heating hourfitted curve50 °C
Each point is one hour of space heating. Lower and flatter is cheaper; well-set radiator systems sit around 35–42 °C at 0 °C outside.
Public system published by its owner on HeatpumpMonitor.org. Cycling (starts per hour) comes from the site’s 365-day statistic. Findings use installer rules of thumb; see methodology.