Heat pumps & heat pump monitoring

OpenEnergyMonitor Trystan LeaThanks to John Cantor heatpumps.co.uk

Using SAP standard temperature of 21C + SAP heating profile Annual heating demand should be: 7318 kWhAt a COP of 3.0 the electric input should be 2439 kWhan average of 6.7 kWh/d.

1.6x ZCB for a floor area ¼ the size!

Monitoring

Headline figuresFrom October 17th to February 7th: 113.3 daysElectric input: 413 kWh (3.6 kWh/d)Heat output: 1405 kWh (12.4 kWh/d)Average COP 3.4

Carbon intensity @ COP 3.4

Detailed monitoring● Electricity input power Watts.● Total electricity input in kWh● Heat output power in Watts● Total heat output in kWh● Outside temperature● Room temperature● Flow temperature● Return temperature

Grid 512gCO2/kWh 151gCO2/kWh

Average Grid Oct → Feb: 318gCO2/kWh

94gCO2/kWh

Heating at peak times 98gCO2/kWh

Matched wind 64gCO2/kWh

Gas heating 230gCO2/kWh

Open source software and hardware heat pump monitorgithub.com/openenergymonitor/HeatpumpMonitor.git

- CT + ACAC Power monitoring- Pulse counting- DS18B20 Temperature sensing- MBUS interface for kamstrup heat meters- ESP2866 WIFI- RFM69 Radio- RaspberryPI GPIO

Carnot COP = (Condensing + 273) / ((Condensing+273) – (Evaporator+273))

Zero Carbon Energy model suggested supply/demand matching level of 57%

Measured matching level of 35% using emoncms.org “my energy” smart grid app.

My heating profile more spiky than model profile.Partially limited by minimum heat pump input power of ~500W.

Next steps

Comparing systems

An open initiative to monitor heat pumps, for householders who wish to get this kind of data for their own systems. Explore how at least headline data from many systems could be shared and compared. Perhaps a pvoutput.org style league table?

Smart grid, demand shifting, better supply/demand matching

Can we design heat pump systems that provide more even, or better matched to renewable supply demand profiles?

Do we need to incorporate thermal stores? At what capacity?

How might better control strategies be developed to automatically provide the best balance between heating in relation to occupancy, comfort, grid stability and renewable supply?