Final August we took a take a look at a number of the choices that led us to construct a low energy home. Now that we’ve been by means of 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 every part else. However first a bit about our setup.
Economic system 7
As an all-electric home, it was necessary to maneuver to an Economic system 7 meter which occurred a number of months after we moved in. This provides us separate Day and Evening charges for our electrical energy. Sadly good meters should not out there in Northern Eire but so there are presently no choices for half-hour metering, demand aspect response or agile tariffs.
The most effective factor we are able to do then is to ensure as a lot of our power utilization is pushed into the evening charge, a 7 hour window which runs from 1am to 8am whereas we’re on GMT and 2am to 9am whereas on British Summer time Time.
All our electrical car charging is finished on the evening charge and our Siemens smart appliances embrace a Delayed Begin perform which has allowed us to set our washer and dishwasher to run throughout the cheaper charge too (we hardly ever want to make use of the dryer as garments dry simply within the heat environment in the home).
The darkish blue strains right here signify the quantity of power we used on the cheaper charge, 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 charge, 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 operating our warmth pump, home equipment in addition to charging the automotive at evening, we genuinely are utilizing a number of wind energy. Round 50% of all electrical energy generated right here is renewable already, with targets for 70% 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 charge tariff (together with VAT);
- Day Fee £0.1699 / kWh
- Evening Fee £0.0784 / kWh
- Standing Cost £3.54 / Month
On high of the conventional fridge and freezer hundreds (both A++ appliances), we even have a number of safety cameras, a 19″ rack with a server, 48 port PoE Change, 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 power 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 scale back it the place potential.
Heating, DHW & Controls
The home is block development with a 150mm cavity, double glazing and has a B85 EPC score 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 Source Heat Pump which is sited on the rear of the home on the storage gable wall.
Our Loxone home 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 many others. Then the Clever Temperature Controller works within the background, grouping our rooms and UFH loops, controlling the movement temperature required with the intention 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 increase the movement temps as required.
Inside the home, each Loxone mild 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 charge too, utilizing the thermal mass of our block development, tiled ground and inner stone wall to launch the warmth throughout the day. Now we have experimented with a few of these methods over the past 12 months, tweaking issues to maneuver as a lot as potential into the evening charge, while sustaining consolation ranges throughout 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 beneath the steps. There could also be just a little power within the ‘Every part Else’ a part of the info beneath, 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 might solely use round 3.3kWh on this instance. A floor supply warmth pump has a fair increased 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 charge, getting issues prepared for the morning showers. The goal is then set again all the way down to 45°. The chrome 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 all the way 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, movement charge, 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 we have now precise power utilization figures for the warmth pump, I presently don’t have any straightforward technique to break down what was on the evening charge versus day. So I’ve used the annual common break up in our payments for this (64% Day, 36% Evening). This must be the worst case situation as the warmth pump is biased to run over evening greater than by means of the day.
- Whole Annual Heating & DHW Power 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 knowledge round 6 months after we moved in. Don’t be disheartened in case you are seeing excessive power prices along with your warmth pump and also you’ve simply completed constructing, as usually power consumption may be increased as the home dries out. Likewise, don’t choose your warmth pump payments from a single month as there’s a massive variation throughout the 12 months. See the proper hand column within the desk beneath for our breakdown.
When it comes to single days, the very 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.
Whole Annual Power Utilization & Prices
The desk and graph beneath exhibits our complete 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 sizzling water, from every part 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 dwelling 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 here are the power consumption figures for the primary full 12 months within the new Automated Residence;
|% of Annual Heating & DHW|
- Whole 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 anything, 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 ‘gas’ for the Electrical automotive.
Comparisons to Final Home
The latest figures I might discover confirmed that 68% of houses in Northern Eire use oil as their major technique of heating (and amazingly 72% nonetheless use strong gas as a secondary technique). In our earlier dwelling, 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 old house 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 outdated payments they usually 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 high of this we used about 10,500 kWh of electrical energy yearly too, giving us these comparative totals;
- OLD Whole 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 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 development employed fundamental 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 onerous 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, we have now diminished our complete power 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 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 truth our bias for operating the heating at evening, 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 shall be no main surprises any time quickly. Nonetheless, upkeep is the one side of the equation that we have now no knowledge on and it must be thought-about.
A few 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. Now we have not seen any of those points. The pump could reverse on a number of days a 12 months to defrost itself however generally the effectivity of the system is excellent (and we’ve seen temperatures as little as -6 up to now).
Observe Jan Rosenow for some nice factual data on warmth pumps and the power transition generally.
I’ve been gathering the info for this submit over the past 12 months and the final third of 2021 noticed unbelievable power value 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, this may finish in the summertime.
We needed to minimize our Photo voltaic PV plans throughout the construct to remain inside finances, 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 diminished. A buddy’s close by 4kWp system produced 524 kWh in June 2021 for instance, which (assuming the identical 87% self-consumption rate as our earlier dwelling) would have nearly halved our invoice for that month from £164 to round £86.
A home battery remains to be an attention-grabbing choice too, both to retailer photo voltaic manufacturing or purchase cheaper electrical energy at evening to be used throughout 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 scale back their emissions. Utilizing an EV for V2G (Automobile to Grid) and V2H (Automobile to Residence) goes to be an attention-grabbing choice sooner or later too.
Some UK blogs discuss receiving £400 a month from their RHI scheme as an incentive to purchase a warmth pump. Nonetheless, Northern Eire presently affords 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 necessary to level out that these financial savings should not simply because we have now 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 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 dwelling with countless sizzling 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.
If you’re constructing or renovating and going the additional mile along with your insulation and airtightness measures, then take a critical take a look at electrified heating.
Are you able to afford to not?
Bear in mind to check out our Instagram to observe the challenge, learn the remainder of the Automated Home 2.0 weblog posts and discover the hyperlinks to all of the products we’ve used in our self-build.