HeatpumpMonitor.org One-Year Data Anniversary

11th December 2023 marks the one-year anniversary of publishing Marsh Flatts Farm’s heat pump performance data to HeatpumpMonitor.org.

For those not familiar with HeatpumpMonitor.org, it’s an online dashboard showing real-world performance metrics for a range of different heat pump installations – mostly in the UK but with a few in other countries.

Main page of HeatpumpMonitor.org, filtered to only show systems with a full year of data

Almost all the installations are Air Source systems and most are Retrofits, replacing gas- or oil-fired boilers. I thought it would be good to contribute a Ground Source system, in a New Build property, for comparison purposes. The main motivation for adding my system was the cold snap forecast for mid-December 2022, with a period of below-freezing temperatures.

From the main page, the Blue icon on each row takes you to a page containing static summary information about each installation, and the Grey icon takes you to the ‘My Heatpump’ App page showing the operational data in a graphical format.

‘My Heatpump’ App View, showing data for the past Month (as of 2023-12-11)

The blue bars are the daily total Electricity Consumption and the yellow bars are the daily total Heat Output. The purple line shows the outdoor temperature (rather more relevant for Air Source systems) and the blue spots are the daily CoP values.

Clicking on one of the daily bars brings up a more detailed view, shown below:

‘My Heatpump’ App View, showing 24 hours of temperature and energy data up to 19:45 on 2023-12-10

The summary information below the graph is a recent addition, breaking out the different Coefficients of Performance for Hot Water (requiring a higher temperature so rather less efficient) and Central Heating – in both cases excluding the power consumption in ‘standby’.

Key Take-Aways

  • In the past year, my system has used 1242 kWh of Electricity to generate 4495 kWh of Heat, giving a Seasonal Coefficient of Performance (SCoP) of 3.62
    • I typically pay about 20 pence per kWh of electricity (on the Intelligent Octopus Go tariff, which is 7.5p for 6 hours overnight then 29.78p for the remaining 18 hours)
    • That means the annual cost for central heating and hot water is about £250, or less than £1 per square metre of floor space
      • Note that about three-quarters of the domestic hot water heating is done by diverting excess solar power generation to the immersion heater, not using the heat pump
  • My system’s SCoP is better-than-average but not great
    • It is significantly more efficient when it’s moving more heat – and it’s more efficient at the start of the heating season (i.e. November and December) when the ground is still relatively warm
      • When switched on without the compressor running (i.e. ‘standby’ mode) it’s consistently drawing 60W, roughly 20W for the circulation pump and 40W for the control system, with no heat output registered on the heat meters (although that heat is still going into the house)
      • Because of this, I switch it off completely over the summer months (end of April to end of September) – and these consumption figures reflect that

HeatpumpMonitor.org is thoroughly successful in meeting its stated aim of demonstrating that heat pumps work very successfully in UK properties and in the UK climate. This is real data from real installations, uploaded by real customers without any vested interests.

The associated Open Energy Monitor community forum (that pre-dates HeatpumpMonitor.org, which is a spin-off from the forum rather than the other way around) is full of knowledgeable and helpful people and is well worth a visit.

Somfy Vertical Blind Automated Control with openHAB

The vast majority of the window blinds are roller blinds with mains motors wired back to MDT blind and shutter actuators using 4-core cables (Live for Up; Live for Down; Neutral; Earth).

The exception is the blind for the large West-facing window in the office, which is trapezoidal (with a sloping top) so the only practical option is a Vertical blind with slats of different lengths.

Large window in second floor office
Large West-facing window in second-floor office, with Vertical Blind in ‘Slats Open’ mode

Good hard-wired control options for this sort of blind proved elusive so it’s got a permanent live mains feed and uses the Somfy RTS system for control. Manual control works very well using the battery powered Somfy Telis 1 Mod/`Var RTS Pure remote control handset, which provides options for:

  • ‘Up’ (fully open, with the slats retracted) using the ^ button
  • ‘Down’ (fully closed, with the slats closed)
  • ‘my’ (which has been configured to the ‘slats across the window but open’ configuration – as shown in the photo above)
  • Fine adjustment of the angle of the slats using the black ‘scroll wheel’
Somfy Telis 1 Mod/Var RTS Pure remote control handset

So manual control is all good; the challenge is automated control from openHAB or a similar home automation control hub.

What’s been working well for years is integration via an RFXcom RFXtrx433E-USB-43392MHz-Transceiver which is managed via the openHAB RFXCOM binding – with just a slight niggle that Open means ‘all the way open, with the slats retracted’ and Closed means ‘all the way closed’. The ideal would be having some way to automate moving to and from the “my” position – so that the slats always remain across the window and only the angle of the slats changes. On the rare occasion of needing the slats retracted to the ‘parking’ position on the left of the window, that can be done with the manual control.

I had been thinking it would necessary to configure a Dimmer-type controller rather than a Switch-type controller, which I’d tried a few times but never got to work. Then I spotted this post on the openHAB forum which explains that the RTS handset uses a custom protocol for the scroll-wheel interaction and using the standard protocol via the RFXcom transceiver there’s no way to say things like ‘close the blinds to 50%:


However, that same forum post highlights it is possible to say ‘go to the “my” position’ by having openHAB send the STOP command rather than the UP or DOWN commands.

In the end it was simply a question of changing “UP” to “STOP” in the rule that opens the Home Office blinds at sunrise (the roller blinds (_01 and _02) still need the “UP” but the vertical blind (_03) gets a “STOP”.

Screenshot of the openHAB rule editor for the Home Office blind automation

(The check for ShadlingLogic <> 2 is so the blinds stay closed when the Shading is set to “Maximum”, where the blinds stay closed all day.)