SteamyTea Posted August 31, 2023 Share Posted August 31, 2023 As we are approaching the heating seasons after one of the most miserable Augusts in recent years, and spurred on by a few comments about when it is best to run a heat pump i.e. night time on the cheap, day time on the not so cheap, I thought I would have a look at my energy and temperature data for last January and February. These are two months when I know my heating is always on as if the mean outside air temperature goes above 9°C, I can turn my heating off, and that usually happens sometime in March down here. I also do not have a heat pump, but that does not make any difference to the house heat load, it just changes the magnitude of what is used. I am though, on Economy 7, which I have modified to Economy 4, even though I usually have all my usage in a 3 hour period from 3 AM to 6 PM, with the occasional on/off for the final hour as the DHW cylinder settles out. Being all electric means that it is very easy to monitor what is happening and when, which I do at the 1 Wh level. This first chart is to just give some context as to the house and outside air temperature. It is not greatly transferable as different houses will be at different temperatures, and local weather, mainly sunshine hours, can make a big difference. But it is useful as it shows the variations in temperatures over the period monitored. It is worth remembering that I have averaged the many thousands of readings down to hourly readings, and the mean, min and max temperatures shown on the chart are taken from the time period analysis rather than the base data, so the real minimum will be a little lower, and the maximum a little higher, but over an hour, they will be right. This next chart, to me, is much more interesting as it shows how often things happen and the magnitude of the events. Really cold times, -3°C and up to 0°C only happened for a total of 24 hours (1.7% of the time). These where probably the two frosty mornings I had (Cornwall is mild, but I am at 200 m altitude and 4.1 kM from the sea). So these times are rare events. Even 0°C up to 5°C is only 470 hours out of the 1410 hours (33%) of the period monitored. The bulk of the time is therefore 5°C and over, 916 hours (65%). Looking at the mean energy usage during those times, -3°C up to 0°C my house used 64.3 kWh, 0°C up to 5°C was 452 kWh and above that 491 kWh. The total for the period was 1008 kWh. Taking the temperatures below 5°C, 35% of the time, the energy usage was 517 kWh, near enough half of the total energy used. The very extreme low temperature though of -3°, only lasted 2 hours and used 0.1 kWh. I am not sure, without looking at the two 'heaviest' times when the OAT is 1°C and 2°C why the usage is disproportionately higher. The most likely reason was that I was away 'up country' just before and this is the house and DHW reheating (I turn the water off and the heating right down when away for more than a night). I think it does show that there may be some merit in using an ASHP during the day if you can store the energy in water or a concrete slab. This will depend on what the price difference between time of use tariffs and a standard tariff is. I currently pay 40.86p/kWh for day rate and 15.05p/kWh night rate before VAT. 7% of my usage was during the day (68 kWh for Jan and Feb), that works out at £28. Pretty low for two winter months. Link to comment Share on other sites More sharing options...
ProDave Posted August 31, 2023 Share Posted August 31, 2023 I have never liked E7 because it penalises you with a higher rate for the daytime. And that then forces you to use the noisy things like washing machine, dishwasher, tumble dryer etc in the middle of the night when you want the house to be quiet. Far better is a single rate tariff, and solar PV, then the best time to heat the house is in the daytime. using a heat pump. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 (edited) 19 minutes ago, ProDave said: penalises you with a higher rate for the daytime. Yes, but at nearly a third of the price at night, and with my usage pattern, still better. The reason I started monitoring was to work out if I would be better off with a fixed tariff. 19 minutes ago, ProDave said: forces you to use the noisy things like washing machine, dishwasher, tumble dryer etc in the middle of the night By better quality appliances. My washing machine does not disturb my sleep, and my house is tiny, washer is only 9 metres from my bed, and I have all the internal doors open at night. We are probably going to be forced down the ToU route, especially after today's announcement about penalising energy producers for rigging there production capacity to fit in with higher demand pricing. https://www.energylivenews.com/2023/08/31/ofgem-cracks-down-on-winter-energy-price-manipulation/ Edited August 31, 2023 by SteamyTea Link to comment Share on other sites More sharing options...
joe90 Posted August 31, 2023 Share Posted August 31, 2023 22 minutes ago, ProDave said: I have never liked E7 because it penalises you with a higher rate for the daytime. I think it depends on your usage pattern. Link to comment Share on other sites More sharing options...
JohnMo Posted August 31, 2023 Share Posted August 31, 2023 Our smart meter coverage is poor, so time of use tariffs may not be available, but octopus is trying an install anyway and if unsuccessful they will manually program for E7. Will have battery installed by then, so 7 hours cheap rate, 13.5kWh of battery either filled by PV or cheap rate, plus any solar generation in day time. So hopefully all or mostly all cheap rate. May have the odd week or so paying some expensive day rate tariff. Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 EDF installed my smart meter a few weeks back. The in home display lasted less than a day. Getting that sorted out has opened a can of worms. They are now claiming that they can only offer me monthly billing, after I have been on quarterly billing for over 30 years. Shall kick up a proper fuss. Link to comment Share on other sites More sharing options...
ProDave Posted August 31, 2023 Share Posted August 31, 2023 7 minutes ago, SteamyTea said: EDF installed my smart meter a few weeks back. The in home display lasted less than a day. Getting that sorted out has opened a can of worms. They are now claiming that they can only offer me monthly billing, after I have been on quarterly billing for over 30 years. Shall kick up a proper fuss. If it ain't broke, don't fix it. you should have refused a smart meter and stuck to your old dual rate E7 meter. 1 Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 1 minute ago, ProDave said: If it ain't broke, don't fix it. you should have refused a smart meter and stuck to your old dual rate E7 meter. The E7 radio service is being switched off, and it also give me the opportunity to try other tariffs and supplier easily. I have nothing against smart metering, but EDF have a hopeless support system. I think they find a homeless person, given them a phone, then teach them how to disconnect customers. But if I keep escalating them problem, I may get 50 quid back. Link to comment Share on other sites More sharing options...
TonyT Posted August 31, 2023 Share Posted August 31, 2023 My day rate is just shy off 4 times more expensive than the night tariff, so a no brainer for charging the EV, storage heaters etc.. dishwasher Hall Storage heater used 9.981kWh last night for the first time in months Hall temps looking ok. Link to comment Share on other sites More sharing options...
TonyT Posted August 31, 2023 Share Posted August 31, 2023 Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 @TonyT It is still August, why is your heater on? My whole house is heated on about 12 kWh/day when it is the coldest time if year. Link to comment Share on other sites More sharing options...
TonyT Posted August 31, 2023 Share Posted August 31, 2023 Remember everyone has different temps they like to heat their homes too and different size of homes so no point in comparing what you use against my consumption. it’s the first time the heating has been on in months Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 1 hour ago, TonyT said: Remember everyone has different temps they like to heat their homes too and different size of homes so no point in comparing what you use against my consumption Why on the face of this it may seem to make sense, you and I probably heat our houses to similar temperatures, and out OATs are probably quite similar, maybe shifted along the x-axis a °C or 3. To put some more light on the matter I have looked at energy use and temperature difference (house temp minus outside temp). Like the previous energy chart, the bulk of the energy usage is in the middle. From Δ12°C to Δ17°C, there is 73% of the total heat load, 712 kWh. Δ17°C to Δ22°C, the coldest periods, 10% of the heat load is used, 112 kWh. The warmest part, Δ8°C to Δ12°C, which accounts for 17% of the time, is 366 kWh This may seem odd that more energy is used to heat the house when it is warmer, but as I said above, it is probably accounted for by being away for a few days. DHW usage will also skew the figures a bit, but they are pretty constant at 3 kWh/day, so about 120 kWh for the period. Another thing that may skew the figures is the amount of winter sunshine and the associated clear nights that cause a larger variation in temperature range, even if the mean temperature is the same. Link to comment Share on other sites More sharing options...
TonyT Posted August 31, 2023 Share Posted August 31, 2023 I like the storage heater as it’s still pushing the heat out now, after the power was switched off at 05:30 am this morning and the temperature at the front vent is 53deg C at 11 pm. Tomorrow will be interesting as last night was heated from cold, so interested to see energy consumption for a consecutive night Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 4 minutes ago, TonyT said: Tomorrow will be interesting as last night was heated from cold, so interested to see energy consumption for a consecutive night Mine generally take a couple of nights to get up to temperature, but then I do limit the hours they can charge to the last 4 hours of the E7 window. This reduces the amount of standing losses during the early morning when the temperature does not need to be so high. Do you have fancy fan assisted smart storage heaters, or dumb, government issue Credit ones like mine. Link to comment Share on other sites More sharing options...
TonyT Posted August 31, 2023 Share Posted August 31, 2023 Dumb creda units. 2x2 brick wide units 1x1 single wide units Think each element is 850 watt controlled via a smart energy plug Link to comment Share on other sites More sharing options...
SteamyTea Posted August 31, 2023 Author Share Posted August 31, 2023 10 minutes ago, TonyT said: controlled via a smart energy plug I just use a cheap electronic timer in each one. I am still in my original elements after 36 years of usage. Those old Credas are a miracle of reliability. Link to comment Share on other sites More sharing options...
Gone West Posted September 1, 2023 Share Posted September 1, 2023 12 hours ago, SteamyTea said: They are now claiming that they can only offer me monthly billing We have been told the same, and I know other people who have had to change to monthly billing. I suspect it's across all suppliers. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 1, 2023 Author Share Posted September 1, 2023 5 minutes ago, Gone West said: We have been told the same, and I know other people who have had to change to monthly billing. I suspect it's across all suppliers. I thought it was sorted out ages ago that the billing has to stay the same. Same times that there cannot be preferential offers for smart meters only. The problem is the call handlers have not been told otherwise, so they believe they can only offer what is on their crib sheets. Link to comment Share on other sites More sharing options...
Gone West Posted September 1, 2023 Share Posted September 1, 2023 32 minutes ago, SteamyTea said: The problem is the call handlers have not been told otherwise, so they believe they can only offer what is on their crib sheets. IIRC we had an email telling us our billing would change from quarterly to monthly and a relative had a note on their bill telling them it was changing from quarterly to monthly. We are with OVO and they are with EDF. Link to comment Share on other sites More sharing options...
TonyT Posted September 1, 2023 Share Posted September 1, 2023 Not much difference in consumption for the the second day, 7am IR thermometer was reading 138deg C on the internal part visible through the front grill Link to comment Share on other sites More sharing options...
TonyT Posted September 1, 2023 Share Posted September 1, 2023 10 hours ago, SteamyTea said: I just use a cheap electronic timer in each one. I am still in my original elements after 36 years of usage. Those old Credas are a miracle of reliability. Yes, fully agree with that statement. My largest unit draw about 1.8kW and as mine are retrofitted, I’m using a smart plug to create time schedules/ monitor consumption. Link to comment Share on other sites More sharing options...
SteamyTea Posted September 1, 2023 Author Share Posted September 1, 2023 @TonyT I am still amazed that you have turned one one. Is there a reason the hall is cold? Where in the country are you? Was the usage half of what is was night before last? Link to comment Share on other sites More sharing options...
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