Hey everyone! As the leaves start turning here in the UK, we’re on the cusp of a big change in our household. In just three days—on October 6th—Octopus Energy will be installing our brand-new Daikin heat pump, completing our multi-year quest to slash energy bills, cut emissions, and future-proof our home. We’ve already ditched petrol/diesel for EVs and solar, and now it’s time to wave goodbye to our aging boiler. If you’re curious about making the switch yourself, pull up a chair. I’ll walk you through what we’ve done, why, and—most excitingly—our predicted savings. Spoiler: It’s a game-changer.
Our story isn’t about overnight perfection; it’s about smart, incremental upgrades that add up. From a dated 1980s house to a low-carbon haven, here’s the full rundown.
Our Home: A Solid Foundation for Efficiency
Living in a 4-bedroom detached house built in the 1980s (113 square meters, with a handy single-story flat-roof extension for our kitchen and dining area) means we’ve had plenty of opportunities to tweak for energy savings. Over the years, we’ve:
- Upgraded to energy-efficient double glazing.
- Boosted loft insulation for better thermal retention.
- Installed cavity wall insulation about 30 years ago (and recently tested it—it’s still doing its job!).
A professional heat loss survey pegged our home at 5,937 watts of loss, with an estimated annual demand of 10,381 kWh for space heating and 3,914 kWh for hot water. These upgrades have helped, but our old gas boiler was on its last legs—serviced regularly, but with dwindling parts availability. Time for an upgrade!
The Heat Pump Leap: From Gas to Green Heating
Enter the Daikin Altherma 3 Monobloc 8 kW (with Blygold corrosion protection)—a beast of an air-source heat pump arriving next week. The total package cost us £5,242 out-of-pocket, including:
- A full radiator upgrade to optimize low-temperature efficiency.
- A shiny new 200L hot water cylinder.
- Switching from our creaky old gravity-fed system to a modern pressurized one.
Without the UK’s Boiler Upgrade Scheme grant of £7,500, this would’ve set us back nearly £13,000. (Pro tip: If your boiler’s still kicking but you’re eyeing a switch, check eligibility—it’s a no-brainer.)
Based on our survey and expected seasonal coefficients (SCOP 3.48 for heating, 2.771 for hot water), we’re projecting ~3,401 kWh of annual electricity use for the heat pump. (Note: A quick double-check suggests it might edge toward 4,396 kWh if we break it down separately— we’ll confirm post-install.)
Our game plan? Power 80% of that (2,720 kWh) with solar or battery-stored energy at an effective 7p/kWh (£190), and the rest (681 kWh) at peak 29p/kWh (£197). Total running cost: under £400/year. Compare that to our old gas setup (12,000 kWh at 6p/kWh = £720/year in units alone), and it’s a solid win—especially since our lifestyle’s shifted. We’re home more now, so heating runs longer than our old “on-when-we’re-around” routine.
Bonus perks: No more gas standing charge (~£107/year at 30p/day) or annual boiler service/gas safety checks (~£120/year, mandatory for us as foster carers). And the first three years of heat pump servicing? Free with the install.
EVs: From Skeptical to Sold
About five years ago, a binge-watch of EV YouTube channels (shoutout to those real-world range tests!) convinced us to go electric.
We started small with a short-range model that fit our needs, but now we’ve got a full fleet: a zippy SEAT Mii Electric for town errands, a Tesla Model 3 for family road trips, and a third EV in the mix for our Daughter – yeah, still living at home.
All second-hand, at prices we’d have paid for petrol cars anyway (SEAT: £8,500; Tesla: £19,000; eGolf: £10,000 ).
We clock ~2,000 miles a month as a family (~24,000/year). At 4 miles/kWh efficiency, that’s 6,000 kWh annually. Thanks to tariffs like Octopus Intelligent Go, we’ve charged at 7p/kWh or less most days—total cost: £420/year. Swap in equivalent petrol/diesel cars at 45 mpg? That’s ~£3,394 in fuel alone. Savings: a whopping £2,974/year. (We’ll dive into servicing cuts—like £200–300 less per car—in a future post.)
We are lucky enough to be able to do pretty much all of our charging at home with the use of our Smart Zappi EV charger from MyEnergi … In the last 12 months, we have only had the need to use public chargers on 2 journeys. This has added £80 to our total energy costs overall.
Solar, Batteries, and Smart Charging: The Power Trio
None of this works without generation and storage. Four years back, we splashed ~£10,000 on a 4.5 kW roof-mounted solar array, two 8.2 kWh GivEnergy batteries (16.4 kWh total), and a home EV charger.
Solar generation for 2024
Worth every penny.
In 2024, solar churned out ~3,200 kWh, with 2,888 kWh exported at 15p/kWh (~£433 credit—double our off-peak buy rate). Our strategy:
- Summer vibes: Export excess solar for max profit; charge batteries/EVs overnight at 7p/kWh to cover house needs.
- Winter mode: Bulk-charge batteries overnight, then draw down during the day. Low battery? Shift laundry or high-drain tasks to the 23:30–05:30 cheapo window.
This kept our 2024 electricity imports (7,112 kWh, including EV top-ups) at ~95% off-peak: 6,756 kWh at 7p (£473) + 356 kWh at 29p (£103) = £576 bill, offset by exports for a sweet net cost.
Pre-all-this? Gas (£720 units) + standard electricity (4,000 kWh at 25p = £1,000) = £1,720/year. Now? A fraction, thanks to arbitrage magic.
Keeping Costs Low: Our Daily Hacks
Want in on the low-cost life? Here’s our playbook:
- Lock in smart tariffs (e.g., Octopus Intelligent Go for those golden 6 off-peak hours).
- App-monitor everything—GivEnergy for batteries, Octopus for usage—to hit 95%+ off-peak.
- Post-heat pump: Sync operation with solar peaks or battery draws.
- Delay big loads (dishwasher, anyone?) to cheap nights.
It’s not rocket science; it’s just intentional.
Standing charges in hatched, Low energy cost in Light Pink, and Higher in Dark Pink.
Septembers electricity bill shows that only 1% of our energy was at peak use.
The Big Reveal: Predicted Annual Savings
Now, the fun part—crunching the numbers. Pre-changes (gas boiler + ICE cars + basic electricity): ~£5,560/year (gas units £720 + standing £107 + service £120; elec units £1,000 + standing £219; car fuel £3,394).
Post-setup net energy cost: ~£641/year. Breakdown:
- EV Fuel: £2,974 saved (£3,394 petrol minus £420 EV charging).
- Heating: £559 saved (£947 gas, including servicing & maintenanc,e total minus ~£388 heat pump running).
- Overall Energy Bill: ~£1,300 trimmed (via solar self-use/export ~£433 credit + off-peak shifts saving ~£500–700 in avoided peaks; net elec ~£418 units + £223 standing charge & servicing costs).
Total Predicted Savings: ~£4,833/year (conservative range: £4,500–£5,200). If heat pump use hits the higher 4,396 kWh estimate, shave off £100–150, landing at ~£4,700. We’ll track real data in the Octopus app and update you—first-year actuals will be gold.
Beyond the Bills: Why We’re All In
Money talks, but this switch whispers “planet.” We’re eyeing ~5,000 kg less CO2/year (gas ~2,200 kg + cars ~4,700 kg, offset by solar-cleaner grid power). Payback? Heat pump in ~9 years; solar/battery in 10–15. Plus, our home’s value could jump 5–10% as an energy-efficient gem.
Risks? Prices flux (Ofgem cap at £1,755 typical use for Q4 2025), and winter sun dips efficiency—keep flow temps under 50°C for peak SCOP >4. Future perks: Vehicle-to-grid tech or ECO4 grants.
What do you think—ready to electrify? Drop a comment if you’re pondering a heat pump or EV swap. We’ve got more posts brewing on servicing savings and install-day drama. Stay tuned, and thanks for reading!
Disclaimer: All figures are estimates based on 2024/2025 rates and our setup. Your mileage (pun intended) may vary—consult pros for personalized advice.
Curious if switching to a heat pump or adding solar panels could cut your energy bills—and whether you’re eligible for the Boiler Upgrade Scheme? Check your options and apply right here: Heat Pump – Solar Quotes. No matter if you opt for a heat pump or solar setup, we’ll both score a £100 Visa gift card once the installation’s done!