Final August we took a take a look at a number of the selections that led us to construct a low vitality residence. Now that we’ve been by 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 essential to maneuver to an Economic system 7 meter which occurred a number of months after we moved in. This provides us separate Day and Night time charges for our electrical energy. Sadly sensible meters usually are not accessible in Northern Eire but so there are at present no choices for half-hour metering, demand aspect response or agile tariffs.
One of the best factor we are able to do then is to ensure as a lot of our vitality utilization is pushed into the night time 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 automobile charging is completed on the night time price and our Siemens sensible home equipment embody a Delayed Begin perform which has allowed us to set our washer and dishwasher to run through 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 beneath reveals nearly a month’s price of knowledge from the wonderful OpenEnergyMonitor (with extra sensors there’s a particular warmth pump measuring system accessible too, take a look at this video).
The darkish blue strains right here signify the quantity of vitality we used on the cheaper price, and it’s simple 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 night time 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 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 working our warmth pump, home equipment in addition to charging the automotive at night time, 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 automobile, an electrified heating system will get cleaner and cleaner over time.
Listed here are the small print of our present mounted price tariff (together with VAT);
- Day Price £0.1699 / kWh
- Night time Price £0.0784 / kWh
- Standing Cost £3.54 / Month
On high of the conventional fridge and freezer hundreds (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 often the bottom line appears to take a seat round 900 Watts. In order that’s round 22kWh per day earlier than we flip anything 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 residence automation system controls the warmth pump through 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 choice making round when to energy as much as increase 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 helpful within the open plan barn for instance.
The Loxone system has been programmed to warmth the home extra on the night time price too, utilizing the thermal mass of our block building, tiled ground and inner stone wall to launch the warmth through the day. We have now experimented with a few of these methods during the last 12 months, tweaking issues to maneuver as a lot as attainable into the night time price, while sustaining consolation ranges through the day.
The warmth pump additionally supplies our scorching water right into a Joule 300 litre DWH (Home Scorching Water) tank which is put in beneath the steps. There could also be slightly vitality within the ‘All the things Else’ a part of the information beneath, 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 models 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 greater 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 price, 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 nearly 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 lots of the heating’s parameters, together with the compressor’s energy, pump velocity, stream 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, nevertheless it has proved to be very helpful.
Annual Heating & DHW Utilization & Prices
Whereas now we have precise vitality utilization figures for the warmth pump, I at present haven’t any simple option to break down what was on the night time price versus day. So I’ve used the annual common cut up in our payments for this (64% Day, 36% Night time). This must be the worst case state of affairs as the warmth pump is biased to run over night time greater than by the day.
- Complete Annual Heating & DHW Power Utilization – 5,345 kWh / £732.05
- Month-to-month Common – 445 kWh / £61.00
- Day by day Common – 15 kWh / £2.01
It’s price stating that I started recording this information 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 typically vitality consumption may be greater as the home dries out. Likewise, don’t decide your warmth pump payments from a single month as there’s a massive variation throughout the 12 months. See the fitting hand column within the desk beneath for our breakdown.
By way of 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 beneath reveals 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 house 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 residence from uni and our daughter and son-in-law got here to stay 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 House;
|All the things
|% of Annual Heating & DHW|
- Complete Annual Power Utilization – 16,276 kWh / £2,273.60
- Month-to-month Common – 1,356 kWh / £189.47
- Day by 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 scorching water, all our cooking and washing, all our Lighting and leisure plus our ‘gasoline’ for the Electrical automotive.
Comparisons to Final Home
The latest figures I might discover confirmed that 68% of properties in Northern Eire use oil as their main technique of heating (and amazingly 72% nonetheless use stable gasoline as a secondary technique). In our earlier residence, 900 litres of heating oil would final us round 4 to five weeks over December / January. The present price for that one fill is round £440 – over half our annual heating price within the new home.
The outdated home was the same 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 outdated 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 high 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 Day by day Common – 156 kWh / £10.92
In financial phrases then, we’re spending nearly 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 all the time have scorching water on faucet. It’s arduous to quantify the standard of life enchancment this brings. Stepping onto heat tiles on a toilet ground within the morning is fairly, fairly good.
Maybe extra importantly, now we have decreased our whole vitality 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 meaning 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 (source). In actual fact our bias for working the heating at night time, coupled with the extraordinary ranges of spare wind energy 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 will likely be no main surprises any time quickly. Nevertheless, upkeep is the one side of the equation that now we have no information on and it must be thought-about.
A number of the unfavourable warmth pump tales I’ve learn point out that the UK and Eire have climates that aren’t appropriate for air supply models. We have now not seen any of those points. The pump might reverse on a number of days a 12 months to defrost itself however basically the effectivity of the system is great (and we’ve seen temperatures as little as -6 to date).
Observe Jan Rosenow for some nice factual info on warmth pumps and the vitality transition basically.
I’ve been gathering the information for this submit during the last 12 months and the final third of 2021 noticed unimaginable vitality price rises. Whether or not you’re 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, it will finish in the summertime.
We needed to lower our Photo voltaic PV plans through the construct to remain inside price range, 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 must be considerably decreased. 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 residence) would have nearly halved our invoice for that month from £164 to round £86.
A home battery continues to be an attention-grabbing choice too, both to retailer photo voltaic manufacturing or purchase cheaper electrical energy at night time to be used through the day. As vitality prices rise, payback occasions for these applied sciences lower. And it’s not all the time in regards to the cash both, for some there will likely be an ethical crucial to attempt to additional cut back their emissions. Utilizing an EV for V2G (Automobile to Grid) and V2H (Automobile to House) goes to be an attention-grabbing choice 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. Nevertheless, Northern Eire at present presents no such assist to encourage owners to do the fitting factor. Let’s hope issues change right here within the close to future
It’s essential to level out that these financial savings usually are 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 specialists we employed – Daly Renewables and Epitome Living. Many 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 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 comfy residence with infinite scorching 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 take a look at electrified heating.
Are you able to afford to not?
Bear in mind to check out our Instagram to observe the venture, learn the remainder of the Automated House 2.0 weblog posts and discover the hyperlinks to all of the merchandise we’ve used in our self-build.