Earth Notes: Saving Electricity and Gas (2017)

Meter readings and energy-saving comments for our dual fuel use in 2017.
2017 PV Output


See the daily PV generation logs for 2017 as .csv and .png chart.

MonthConsumed kWh (/d)Generated -kWh (/d)Consumed kWh (/d) PeriodNotes
2017/01 207 (6.7/d) -71 (-2.3/d) 867 (28/d) 20161231-18:29-GMT to 20170131-18:44-GMT (31d) Meter readings: electricity generation 70.6kWh, export 41.1kWh, import 177.7kWh (thus net consumption (I+G-E) 207.2kWh); gas ~77.2m^3 (so 867kWh @ 11.1kWh/m^3).
HDD12=248 vs 173 last January.
2017/02 163 (5.8/d) -109 (-3.9/d) 497 (18/d) 20170131-18:44-GMT to 20170228-23:37-GMT (28d) Meter readings: electricity generation 109.4kWh, export 78.8kWh, import 132.4kWh (thus net consumption (I+G-E) 163.0kWh); gas ~44.8m^3 (so 497kWh @ 11.1kWh/m^3).
HDD12=139 vs 199 last February.
2017/03 166 (5.4/d) -300 (-9.7/d) 357 (12/d) 20170228-23:37-GMT to 20170331-16:29-GMT (31d) Meter readings: electricity generation 300.2kWh, export 244.3kWh, import 110.0kWh (thus net consumption (I+G-E) 165.9kWh); gas ~32.1m^3 (so 357kWh @ 11.1kWh/m^3).
HDD12=77 vs 162 last March.
2017/04 143 (4.8/d) -482 (-16/d) 117 (3.9/d) 20170331-16:29-GMT to 20170430-20:45-GMT (30d) Meter readings: electricity generation 481.9kWh, export 407.5kWh, import 68.8kWh (thus net consumption (I+G-E) 143.2kWh); gas ~10.5m^3 (so 117kWh @ 11.1kWh/m^3).
HDD12=65 vs 104 last April.
2017/05 149 (4.8/d) -528 (-17/d) 142 (4.6/d) 20170430-20:45-GMT to 20170521-19:54-GMT (31d) Meter readings: electricity generation 527.7kWh, export 450.5kWh, import 71.5kWh (thus net consumption (I+G-E) 148.7kWh); gas ~12.8m^3 (so 142kWh @ 11.1kWh/m^3).
HDD12=23 vs 23 last May.
2017/06 139 (4.6/d) -622 (-21/d) 109 (3.6/d) 20170521-19:54-GMT to 20170630-19:28-GMT (30d) Meter readings: electricity generation 621.7kWh, export 545.4kWh, import 63.1kWh (thus net consumption (I+G-E) 139.4kWh); gas ~9.8m^3 (so 109kWh @ 11.1kWh/m^3).
HDD12=1 vs 2 last June.
2017 running total (Jan--Jun) 967 (5.3/d) -2112 (-12/d) 2079 (11/d) 20161231-18:29-GMT to 20170630-19:28-GMT (181d) Implies total footprint to date -46kgCO2: electricity (average 223W gross) -492kgCO2e @ 0.43kgCO2/kWh (netted), gas 395kgCO2e @ 0.19kgCO2/kWh.
2017/07 147 (4.8/d) -561 (-18/d) 105 (3.4/d) 20170630-19:28-GMT to 20170731-18:56-GMT (31d) Meter readings: electricity generation 560.5kWh, export 477.3kWh, import 64.2kWh (thus net consumption (I+G-E) 147.4kWh); gas ~9.5m^3 (so 105kWh @ 11.1kWh/m^3).
HDD12=0 vs 0 last July.
2017/08 97 (2.9/d) -519 (-16/d) 60 (1.8/d) 20170731-18:56-GMT to 20170902-17:26-GMT (33d) Meter readings: electricity generation 519.0kWh, export 472.3kWh, import 50.1kWh (thus net consumption (I+G-E) 96.9kWh); gas ~5.4m^3 (so 60kWh @ 11.1kWh/m^3).
Two weeks' holiday reduced fuel demand as expected. Baseline gas demand is ~0 at this time of year (demand DHW only). Baseline electricity demand is ~1kWh/d, mainly for fridge. (Compare daily consumption w/ July, given ~50% absence this month.)
HDD12=1 vs 0 last August.

2017/05: Ecotricity sent our annual summaries for electricity and gas, stating that we had used just over 1.3MWh of electricity (~£270) and a ~4.2MWh of gas (~£262).

The gas figure is higher than usual, given that it was a cold winter, and ~3.5MWh would be more typical (maybe ~£250).

Given that we don't yet have a heat-pump, but that resistance heating is beginning to approach the carbon intensity of gas on the GB grid (currently ~300gCO2/kWh vs ~190gCO2/kWh), what would be the effect of moving from gas to electricity for all heat including water (DHW)?

At ~17p/kWh for electricity that 3.5MWh would be ~£600, but getting rid of gas and its standing charge and an annual gas boiler inspection/service would leave us 'just' net ~£250 per year worse off. Ie we might expect a £900/year electricity bill, rather than a £550 dual-fuel total (+~£100 maintenance).

Moving all our DWH consumption to solar PV that we'd otherwise export (eg with the help of a resistance-driven Sunamp store) would be roughly cost neutral, since the gas per-kWh cost is similar to what we are paid for electricity exports.

Even in the depths of winter, we export in electricity ~10% of what we consume in gas; a heat-pump and store could double that to ~20%, still requiring us to import the remaining 80%. In the shoulder months with a suitable Sunamp-like store we could probably cover all space heating. Without a heat-pump the effect on utility bills of using our own power locally is roughly neutral, though kind to grid in avoiding shipping that energy back and forth.