Final August we took a have a look at among the choices that led us to construct a low vitality house. Now that we’ve been via our first full calendar 12 months, it’s time to disclose our vitality invoice and see how issues are figuring out. I’ve separated out figures for the warmth pump versus all the things else. However first a bit about our setup.
Economic system 7
As an all-electric home, it was vital to maneuver to an Economic system 7 meter which occurred a couple of months after we moved in. This provides us separate Day and Night time charges for our electrical energy. Sadly sensible meters are usually not accessible in Northern Eire but so there are at the moment no choices for half-hour metering, demand aspect response or agile tariffs.
The perfect factor we are able to do then is to ensure as a lot of our vitality utilization is pushed into the evening price, 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 car charging is finished on the evening price and our Siemens sensible home equipment embrace a Delayed Begin perform which has allowed us to set our washer and dishwasher to run in the course of the cheaper price too (we hardly ever want to make use of the dryer as garments dry simply within the heat environment in the home).
The graph under exhibits virtually a month’s price of knowledge from the superb OpenEnergyMonitor (with extra sensors there’s a selected warmth pump measuring system accessible too, try this video).
The darkish blue strains right here signify the quantity of vitality we used on the cheaper price, and it’s straightforward to identify the 5 nights that the EV was charged throughout this era.
Throughout the 12 months a mean of 36% of our consumption was on the evening price, with the height in December at 48%.
Pricing & Hundreds
We’re on a 100% renewable tariff and whereas the electrons from the wind farms aren’t really flowing to our home, I consider selecting a tariff like this encourages the mills to spend money on extra renewables. And as we’re working our warmth pump, home equipment in addition to charging the automobile at evening, we genuinely are utilizing numerous wind energy. Round 50% of all electrical energy generated right here is renewable already, with targets for 80% by 2030, so identical to with an electrical car, an electrified heating system will get cleaner and cleaner over time.
Listed here are the small print of our present fastened price tariff (together with VAT);
- Day Charge £0.1699 / kWh
- Night time Charge £0.0784 / kWh
- Standing Cost £3.54 / Month
On prime of the traditional fridge and freezer masses (each A++ home equipment), we even have numerous safety cameras, a 19″ rack with a server, 48 port PoE Swap, NAS, 6-Zone Complete 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 vitality 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 prefer to look into this base load in additional element this 12 months and try to cut back it the place doable.
Heating, DHW & Controls
The home is block development 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 capabilities 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 theClever Temperature Controller works within the background, grouping our rooms and UFH loops, controlling the circulation 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 skin temperature readings from our climate station. The warmth pump itself then does its personal choice making round when to energy as much as enhance the circulation temps as required.
Inside the home, each Loxone gentle change 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 evening price too, utilizing the thermal mass of our block development, tiled flooring and inner stone wall to launch the warmth in the course of the day. We’ve experimented with a few of these methods over the past 12 months, tweaking issues to maneuver as a lot as doable into the evening price, while sustaining consolation ranges in the course of the day.
The warmth pump additionally offers our sizzling water right into a Joule 300 litre DWH (Home Sizzling Water) tank which is put in under the steps. There could also be a bit vitality within the ‘Every part Else’ a part of the info under, for the uncommon event that the system activates the immersion heater if the warmth pump can not refill the tank shortly sufficient.
Water heating makes use of a shocking quantity of vitality 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 items of warmth for each 1 unit of electrical energy consumed, so we might solely use round 3.3kWh on this instance. A floor supply warmth pump has an excellent larger COP than our air supply unit.
The system quickly raises our sizzling water goal temperature to 55° each morning at 6:00am, whereas we’re nonetheless on the cheaper evening price, getting issues prepared for the morning showers. The goal is then set again down to45°. 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 normal45° goal.
The Loxone system additionally permits us to watch the standing of lots of the heating’s parameters, together with the compressor’s energy, pump velocity, circulation price, 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, however it has proved to be very helpful.
Annual Heating & DHW Utilization & Prices
Whereas now we have actual vitality utilization figures for the warmth pump, I at the moment don’t have any straightforward method to break down what was on the evening price versus day. So I’ve used the annual common cut up in our payments for this (64% Day, 36% Night time). This needs to be the worst case situation as the warmth pump is biased to run over evening greater than via the day.
- Complete Annual Heating & DHW Power Utilization – 5,345 kWh / £732.05
- MonthlyAverage – 445 kWh / £61.00
- Every day Common – 15 kWh / £2.01
It’s price stating that I started recording this knowledge round 6 months after we moved in. Don’t be disheartened in case you are seeing excessive vitality prices along with your warmth pump and also you’ve simply completed constructing, as usually vitality consumption will 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 proper hand column within the desk under for our breakdown.
When it comes to single days, the best vitality 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 Power Utilization & Prices
The desk and graph under exhibits our whole vitality used final 12 months in kWh, damaged down into 2 values, separating the vitality mentioned above that was utilized by the warmth pump for area heating and sizzling water, from all the things else.
You’ll discover a rise in consumption in March the place you’d 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 vitality consumption (rattling that PS4).
So listed here are the vitality consumption figures for the primary full 12 months within the new Automated Dwelling;
|% of Annual Heating & DHW|
- Complete Annual Power Utilization – 16,276 kWh / £2,273.60
- Month-to-month Common – 1,356 kWh / £189.47
- Every day Common – 45 kWh / £6.23
Bear 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 sizzling water, all our cooking and washing, all our Lighting and leisure plus our ‘gasoline’ for the Electrical automobile.
Comparisons to Final Home
The most recent figures I may discover confirmed that 68% of properties in Northern Eire use oil as their main technique of heating (and amazingly 72% nonetheless use strong gasoline as a secondary technique). 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 measurement, 275 sq m / 3,000 sq ft (together with the built-in storage) and whereas I don’t have detailed knowledge, I do have entry to my previous payments they usually present we averaged 5 x 900 litre fills of heating oil annually. In vitality 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 Power 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 development employed primary ranges of insulation and no airtightness measures. The brand new home is heat evening and day, in each room, we at all times have sizzling water on faucet. It’s arduous to quantify the standard of life enchancment this brings. Stepping onto heat tiles on a rest room flooring within the morning is fairly, fairly good.
Maybe extra importantly, now we have lowered our whole vitality consumption by greater than 70%, together with all of the related CO2 financial savings and air high quality enhancements (try this knowledge from our Airthings Wave Plus).
The most recent 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 meaning lower than 100grams ofCO2 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). The truth is our bias for working the heating at evening, coupled with the extraordinary ranges of spare wind vitality in NI, means we could also be doing higher than that.
The warmth pump has a 7 12 months components guarantee (3 years labour) so hopefully there will likely be no main surprises any time quickly. Nonetheless, upkeep is the one facet of the equation that now we have no knowledge on and it must be thought-about.
Among the adverse warmth pump tales I’ve learn point out that the UK and Eire have climates that aren’t appropriate for air supply items. We’ve not seen any of those points. The pump might reverse on a couple of days a 12 months to defrost itself however typically the effectivity of the system is excellent (and we’ve seen temperatures as little as -6 thus far).
Observe Jan Rosenow for some nice factual data on warmth pumps and the vitality transition typically.
I’ve been gathering the info for this publish over the past 12 months and the final third of 2021 noticed unimaginable vitality 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 reduce our Photo voltaic PV plans in the course of the construct to remain inside price range, however we hope to purchase a system, maybe this 12 months, to try to off-set a few of these worth rises. As soon as put in, prices for the brighter months needs to be considerably lowered. A good friend’s close by 4kWp system produced 524 kWh in June 2021 for instance, which (assuming the identical 87% self-consumption price 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 evening to be used in the course of the day. As vitality prices rise, payback occasions for these applied sciences lower. And it’s not at all times in regards to the cash both, for some there will likely be an ethical crucial to try 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 speak about receiving £400 a month from their RHI scheme as an incentive to purchase a warmth pump. Nonetheless, Northern Eire at the moment gives no such assist to encourage householders to do the proper factor. Let’s hope issues change right here within the close to future
It’s vital to level out that these financial savings are usually not simply because now we have an electrified heating system. The insulation and airtightness measures within the new home are important to the success right here. As is the involvement of the consultants we employed – Daly Renewables and Epitome Dwelling. A lot of the complaints I learn round warmth pumps are from initiatives that didn’t have a correctly designed or fitted system.
Whereas there are many extra vitality environment friendly properties 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 snug house with infinite sizzling water, for round half the working prices of the oil fired home, all whereas producing far much less GHG and air air pollution than earlier than.
If you’re constructing or renovating and going the additional mile along with your insulation and airtightness measures, then take a severe have a look at electrified heating.
Are you able to afford to not?
Bear in mind to try our Instagram to observe the venture, 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.