Final August we took a have a look at a few of the selections that led us to construct a low power house. Now that we’ve been via our first full calendar 12 months, it’s time to disclose our power invoice and see how issues are understanding. I’ve separated out figures for the warmth pump versus all the things else. However first a bit about our setup.
Financial system 7
As an all-electric home, it was vital to maneuver to an Financial system 7 meter which occurred a number of months after we moved in. This offers us separate Day and Evening charges for our electrical energy. Sadly sensible meters are usually not accessible in Northern Eire but so there are at present no choices for half-hour metering, demand aspect response or agile tariffs.
The very best factor we will do then is to verify as a lot of our power utilization is pushed into the night time fee, a 7 hour window which runs from 1am to 8am whereas we’re on GMT and 2am to 9am whereas on British Summer season Time.
All our electrical automobile charging is completed on the night time fee and our Siemens sensible home equipment embody a Delayed Begin perform which has allowed us to set our washer and dishwasher to run in the course of the cheaper fee too (we not often want to make use of the dryer as garments dry simply within the heat ambiance in the home).
The graph under exhibits virtually a month’s value of knowledge from the superb OpenEnergyMonitor (with extra sensors there’s a selected warmth pump measuring system accessible too, take a look at this video).
The darkish blue traces right here characterize the quantity of power we used on the cheaper fee, and it’s straightforward to identify the 5 nights that the EV was charged throughout this era.
Throughout the 12 months a median of 36% of our consumption was on the night time fee, with the height in December at 48%.
Pricing & Masses
We’re on a 100% renewable tariff and whereas the electrons from the wind farms aren’t truly flowing to our home, I imagine selecting a tariff like this encourages the turbines to put money into extra renewables. And as we’re operating our warmth pump, home equipment in addition to charging the automotive at night time, we genuinely are utilizing a number of wind energy. Round 50% of all electrical energy generated right here is renewable already, with targets for 80% by 2030, so similar to with an electrical automobile, an electrified heating system will get cleaner and cleaner over time.
Listed here are the main points of our present mounted fee tariff (together with VAT);
- Day Charge £0.1699 / kWh
- Evening Charge £0.0784 / kWh
- Standing Cost £3.54 / Month
On prime of the traditional fridge and freezer hundreds (each A++ home equipment), we even have a number of safety cameras, a 19″ rack with a server, 48 port PoE Change, NAS, 6-Zone Entire Home Audio amplifier, and MVHR (even our septic tank has a 24/7 draw), so our base load is excessive. The bottom determine I’ve seen from our power monitor is round 725 Watts, however extra normally the bottom line appears to take a seat round 900 Watts. In order that’s round 22kWh per day earlier than we flip the rest on. I’d wish to look into this base load in additional element this 12 months and attempt to cut back it the place attainable.
Heating, DHW & Controls
The home is block building with a 150mm cavity, double glazing and has a B85 EPC ranking which ought to hit an A as soon as we add a photo voltaic PV system. Heating is from this 11kW Hitachi Yutaki M Monobloc Air Supply Warmth Pump which is sited on the rear of the home on the north going through storage gable wall.
Our Loxone house automation system controls the warmth pump by way of a TCP/IP Modbus Gateway (ATW-MBS-02). Each upstairs and downstairs use Roth underfloor heating fed from three manifolds round the home, utilizing Loxone valve actuators.
Loxone brings three, core heating / local weather management features to the system. The Clever Room Controller is accessible from the UI, and is used to view the present room temperature, change the set factors and timing and so on. Then the Clever Temperature Controller works within the background, grouping our rooms and UFH loops, controlling the stream temperature required to be able to obtain the temperatures demanded by the room controllers. Lastly the Local weather Controller turns the warmth pump on and off, whereas additionally contemplating the surface temperature readings from our climate station. The warmth pump itself then does its personal resolution making round when to energy as much as enhance the stream temps as required.
Inside the home, each Loxone gentle swap has a built-in temperature (and humidity) sensor which we use because the room thermostats. The Loxone system can common values throughout a number of sensors which is useful within the open plan barn for instance.
The Loxone system has been programmed to warmth the home extra on the night time fee too, utilizing the thermal mass of our block building, tiled flooring and inside stone wall to launch the warmth in the course of the day. We now have experimented with a few of these methods over the past 12 months, tweaking issues to maneuver as a lot as attainable into the night time fee, while sustaining consolation ranges in the course of the day.
The warmth pump additionally supplies our scorching water right into a Joule 300 litre DWH (Home Sizzling Water) tank which is put in under the steps. There could also be slightly power within the ‘Every part Else’ a part of the information under, for the uncommon event that the system activates the immersion heater if the warmth pump can’t refill the tank rapidly sufficient.
Water heating makes use of a stunning quantity of power and warming 300 litres from an ambient of say 16° to our 45° goal makes use of over 10 kWh. The warmth pump’s COP (coefficient of efficiency) means we get round 3 models of warmth for each 1 unit of electrical energy consumed, so we’d solely use round 3.3kWh on this instance. A floor supply warmth pump has a good larger COP than our air supply unit.
The system quickly raises our scorching water goal temperature to 55° each morning at 6:00am, whereas we’re nonetheless on the cheaper night time fee, getting issues prepared for the morning showers. The goal is then set again right down to 45°. The stainless-steel tank is rated to lose round 1° each 4 hours so, if unused, ought to take virtually 40 hours earlier than it cools again right down to our regular 45° goal.
The Loxone system additionally permits us to watch the standing of most of the heating’s parameters, together with the compressor’s energy, pump velocity, stream fee, alarm standing, outlet and inlet temperatures, DWH temperature, in addition to the positions of the three port valve and motorised valves on the manifolds. It’s nonetheless a piece in progress, and we have to get a greater graphic, but it surely has proved to be very helpful.
Annual Heating & DHW Utilization & Prices
Whereas we now have actual power utilization figures for the warmth pump, I at present haven’t any straightforward technique to break down what was on the night time fee versus day. So I’ve used the annual common break up in our payments for this (64% Day, 36% Evening). This ought to be the worst case situation as the warmth pump is biased to run over night time greater than via the day.
- Complete Annual Heating & DHW Vitality Utilization – 5,345 kWh / £732.05
- Month-to-month Common – 445 kWh / £61.00
- Every day Common – 15 kWh / £2.01
It’s value mentioning that I started recording this information round 6 months after we moved in. Don’t be disheartened in case you are seeing excessive power prices together with your warmth pump and also you’ve simply completed constructing, as typically power consumption might be larger as the home dries out. Likewise, don’t choose your warmth pump payments from a single month as there’s a giant variation throughout the 12 months. See the fitting hand column within the desk under for our breakdown.
When it comes to single days, the best power consumption for the warmth pump was twenty seventh November at 39.4 kWh, whereas the bottom was an order of magnitude much less at 3.9 kWh on sixteenth July.
Complete Annual Vitality Utilization & Prices
The desk and graph under exhibits our whole power used final 12 months in kWh, damaged down into 2 values, separating the power mentioned above that was utilized by the warmth pump for area heating and scorching water, from all the things else.
You’ll discover a rise in consumption in March the place you’ll have anticipated it to fall because the climate continued to heat up. This was as a result of our son got here house from uni and our daughter and son-in-law got here to reside with us too (between home strikes). So we went from 2 adults to five in a single day, with all of the related further power consumption (rattling that PS4).
So listed below are the power consumption figures for the primary full 12 months within the new Automated Dwelling;
| 2021 Month |
Warmth Pump |
Every part Else |
Complete kWh |
% of Annual Heating & DHW |
|---|---|---|---|---|
| January | 787 | 869 | 1,656 | 14.8% |
| February | 655 | 715 | 1,369 | 12.2% |
| March | 607 | 923 | 1,530 | 11.3% |
| April | 475 | 982 | 1,457 | 8.9% |
| Might | 354 | 969 | 1,323 | 6.8% |
| June | 214 | 905 | 1,119 | 4.0% |
| July | 194 | 948 | 1,142 | 3.6% |
| August | 214 | 860 | 1,074 | 4.0% |
| September | 214 | 907 | 1,120 | 4.0% |
| October | 308 | 818 | 1,126 | 5.7% |
| November | 518 | 1,018 | 1,536 | 9.7% |
| December | 806 | 1,018 | 1,824 | 15.0% |
| TOTALS | 5,345 | 10,931 | 16,276 | 100% |
- Complete Annual Vitality Utilization – 16,276 kWh / £2,273.60
- Month-to-month Common – 1,356 kWh / £189.47
- Every day Common – 45 kWh / £6.23
Keep in mind, we aren’t burning something, we purchase no fuel, heating oil, coal, wooden, petrol or diesel. In order that £189 (common) is our single month-to-month invoice for all our heating and scorching water, all our cooking and washing, all our Lighting and leisure plus our ‘gasoline’ for the Electrical automotive.
Comparisons to Final Home
The newest figures I may discover confirmed that 68% of houses in Northern Eire use oil as their main methodology of heating (and amazingly 72% nonetheless use stable gasoline as a secondary methodology). In our earlier house, 900 litres of heating oil would final us round 4 to five weeks over December / January. The present value for that one fill is round £440 – over half our annual heating value within the new home.
The previous home was an identical dimension, 275 sq m / 3,000 sq ft (together with the built-in storage) and whereas I don’t have detailed information, I do have entry to my previous payments and so they present we averaged 5 x 900 litre fills of heating oil annually. In power phrases, that 4,500 litres represents roughly 46,500 kWh and on prime of this we used about 10,500 kWh of electrical energy yearly too, giving us these comparative totals;
- OLD Complete Annual Vitality Utilization – 57,000 kWh / £3,985
- OLD Month-to-month Common – 4,750 kWh / £332.08
- OLD Every day Common – 156 kWh / £10.92
In financial phrases then, we’re spending virtually half what we did within the final home. However the financial savings are solely half the story, because it’s the rise in consolation ranges which can be most noticeable. The final home was constructed within the late 90’s and its conventional building employed primary ranges of insulation and no airtightness measures. The brand new home is heat night time and day, in each room, we at all times have scorching water on faucet. It’s arduous to quantify the standard of life enchancment this brings. Stepping onto heat tiles on a toilet flooring within the morning is fairly, fairly good.
Maybe extra importantly, we now have diminished our whole power consumption by greater than 70%, together with all of the related CO2 financial savings and air high quality enhancements (take a look at this information from our Airthings Wave Plus).
The newest figures I can discover (2019) present that 330 grams of CO2 was produced per kWh of electrical energy generated in Northern Eire. Assuming a COP of three.2 which means lower than 100 grams of CO2 per kWh of warmth. That’s round half the CO2 emissions of a mains fuel boiler and round a 3rd of an oil fired heating system (supply). In reality our bias for operating the heating at night time, coupled with the extraordinary ranges of spare wind power in NI, means we could also be doing higher than that.
The warmth pump has a 7 12 months elements guarantee (3 years labour) so hopefully there shall be no main surprises any time quickly. Nevertheless, upkeep is the one facet of the equation that we now have no information on and it must be thought-about.
A number of the adverse warmth pump tales I’ve learn point out that the UK and Eire have climates that aren’t appropriate for air supply models. We now have not seen any of those points. The pump might reverse on a number of days a 12 months to defrost itself however on the whole the effectivity of the system is great (and we’ve seen temperatures as little as -6 thus far).
Comply with Jan Rosenow for some nice factual data on warmth pumps and the power transition on the whole.
The Future
I’ve been gathering the information for this publish over the past 12 months and the final third of 2021 noticed unimaginable power value rises. Whether or not you might be utilizing electrical energy or burning fuel or oil, costs have seen unprecedented will increase over this time. Whereas we’ve been fortunate to be on a fix-rate tariff, this can finish in the summertime.
We needed to lower our Photo voltaic PV plans in the course of the construct to remain inside funds, however we hope to purchase a system, maybe this 12 months, to attempt to off-set a few of these worth rises. As soon as put in, prices for the brighter months ought to be considerably diminished. A pal’s close by 4kWp system produced 524 kWh in June 2021 for instance, which (assuming the identical 87% self-consumption fee as our earlier house) would have virtually halved our invoice for that month from £164 to round £86.
A home battery remains to be an fascinating possibility too, both to retailer photo voltaic manufacturing or purchase cheaper electrical energy at night time to be used in the course of the day. As power prices rise, payback instances for these applied sciences lower. And it’s not at all times in regards to the cash both, for some there shall be an ethical crucial to attempt to additional cut back their emissions. Utilizing an EV for V2G (Automobile to Grid) and V2H (Automobile to Dwelling) goes to be an fascinating possibility sooner or later too.
Some UK blogs discuss receiving £400 a month from their RHI scheme as an incentive to purchase a warmth pump. Nevertheless, Northern Eire at present provides no such assist to encourage owners to do the fitting factor. Let’s hope issues change right here within the close to future
Success
It’s vital to level out that these financial savings are usually not simply because we now have an electrified heating system. The insulation and airtightness measures within the new home are very important to the success right here. As is the involvement of the specialists we employed – Daly Renewables and Epitome Dwelling. A lot of the complaints I learn round warmth pumps are from tasks that didn’t have a correctly designed or fitted system.
Whereas there are many extra power environment friendly houses than ours, we’re delighted with the efficiency of the constructing and its cleaner, quieter, low carbon heating system. We’re having fun with a a lot hotter, extra comfy house with infinite scorching water, for round half the operating prices of the oil fired home, all whereas producing far much less GHG and air air pollution than earlier than.
In case you are constructing or renovating and going the additional mile together with your insulation and airtightness measures, then take a critical have a look at electrified heating.
Are you able to afford to not?
UPDATE – see the figures for the 2022 right here
Keep in mind to take a look at our Instagram to comply with the challenge, learn the remainder of the Automated Dwelling 2.0 weblog posts and discover the hyperlinks to all of the merchandise we’ve used in our self-build.
