Octopus Energy Cosy tariff: can it cut UK heating bills?
A UK-focused guide to Octopus Energy Cosy (heat pump time-of-use tariff): how it works, who it suits, typical costs, and the checks to do before you switch.
- Answer-first summary with realistic examples (with assumptions)
- Eligibility, meter and heat pump requirements explained in plain English
- Compare against standard variable and other time-of-use approaches
Estimates only. Tariff availability, prices and eligibility can change. Always check your supplier’s current tariff details and your heat pump setup before switching.
Fast answer: “Octopus Energy Cosy tariff cut bills UK”
Octopus Energy Cosy tariff cut bills UK households can see lower heat pump running costs if they can shift a meaningful share of heating (and hot water) into Cosy’s cheaper off‑peak windows. The key factor is how much electricity you can move away from peak-rate hours, not your home’s size—results vary by usage, region and tariff rates.
Key takeaway 1
Cosy is designed for electric heat pumps plus a smart meter. If you don’t have a heat pump, it’s unlikely to be suitable.
Key takeaway 2
The most important check is your “load shifting” ability: can your heat pump pre-heat the home or hot water during cheaper hours without comfort issues?
Key takeaway 3
Always compare the full unit rates + standing charge against alternatives available to you. A cheaper off‑peak rate can be offset by higher peak rates.
Important: EnergyPlus is whole-of-market comparison. This page explains Cosy and how to judge it. We don’t promise savings and we don’t assume Cosy is best—your cheapest option depends on your usage pattern and what tariffs you can access.
What is Octopus Energy Cosy?
Octopus Energy Cosy is a time-of-use electricity tariff aimed at homes with heat pumps. Instead of one flat unit rate all day, you get cheaper “off-peak” unit rates at set times and a higher “peak” rate at others (plus a daily standing charge).
The idea is simple: if your heat pump can do more work when electricity is cheaper (for example, topping up hot water or gently pre-heating), your average cost per kWh across the day may drop.
Who Cosy is usually aimed at
- Homes with an air source or ground source heat pump
- A working smart meter capable of half-hourly readings
- Households that can shift some heating/hot water demand into cheaper windows
Comfort comes first: heat pumps work best when they run steadily. “Load shifting” is typically about small adjustments (flow temperature, hot water timing, gentle pre-heat), not turning heating fully off for long periods in winter.
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Use EnergyPlus to compare whole-of-market options (including heat-pump-friendly tariffs where available). We’ll use your details to prepare a quote and explain your next steps.
The 5 checks that decide whether Cosy can reduce your costs
- You have a heat pump (Cosy is built around heat pump demand).
- You have a smart meter sending half-hourly readings reliably.
- Your peak-time electricity use isn’t huge (cooking, tumble dryer, immersion heater during peak can erode benefits).
- Your heat pump controls support scheduling (or you’re comfortable setting heating/hot water schedules).
- The tariff’s standing charge + unit rates beat your alternatives for your expected usage pattern.
Tip: If you can download half-hourly consumption data from your current supplier (or from your in-home display where available), you can estimate what proportion of usage lands in off‑peak vs peak windows and stress-test whether Cosy is likely to help.
Scenario 1 (estimated): heat pump + good load shifting
Assumptions (illustrative): 12,000 kWh/year electricity total (all-electric home with heat pump), standing charge ignored for simplicity in this example, and you can move 45% of usage into off‑peak windows. Example rates used: off‑peak 15p/kWh, peak 35p/kWh. Flat alternative: 27p/kWh.
| Calculation | Estimated annual cost |
|---|---|
| Cosy-style TOU: 45% at 15p + 55% at 35p | £3,060 |
| Flat rate: 100% at 27p | £3,240 |
| Difference (illustrative) | £180/year lower |
Why this can happen: a heat pump can “pull forward” some demand to cheaper windows (especially hot water), reducing the weighted average rate. Real tariffs include standing charges, and actual time windows/rates vary.
Scenario 2 (estimated): limited load shifting + high peak use
Assumptions (illustrative): 8,000 kWh/year electricity, only 20% can be moved off‑peak, and evening cooking/laundry falls in peak. Same example rates as above (15p/35p vs 27p flat), standing charge ignored for simplicity.
| Calculation | Estimated annual cost |
|---|---|
| Cosy-style TOU: 20% at 15p + 80% at 35p | £2,360 |
| Flat rate: 100% at 27p | £2,160 |
| Difference (illustrative) | £200/year higher |
This is the main risk with any time-of-use tariff: if too much consumption stays in peak, the higher rate can outweigh the off-peak benefit.
Cosy vs other common UK options (what to compare)
The best comparison is the tariff you can actually get at your address, on your meter, with your payment method. Use this table to focus on the features that typically change the bill outcome.
| Tariff type | Best for | Main upside | Main trade-off |
|---|---|---|---|
| Octopus Cosy (TOU for heat pumps) | Heat pump homes that can shift usage | Cheaper windows can cut weighted average cost | Higher peak rate can punish peak-heavy households |
| Standard Variable Tariff (SVT) | Anyone wanting simplicity/flexibility | No fixed term; easier to leave | Often not the cheapest for predictable usage |
| Fixed tariff (single rate) | Budgeting over a set period | Price certainty for unit rate/standing charge | May include exit fees; less responsive to off-peak behaviour |
| Other time-of-use tariffs | Homes with flexible demand (EV, battery, some heat pump setups) | Can reward shifting big loads | More complex; peak periods matter a lot |
Quick checklist: Cosy is more likely to suit you if…
- You can schedule hot water heating into off‑peak
- Your home holds heat reasonably well (or you’re happy with gentle pre‑heat)
- You can avoid heavy appliance use in peak (tumble dryer, dishwasher, immersion)
- You track usage and are comfortable adjusting settings seasonally
Cosy may not suit you if…
- You don’t have a heat pump (or it’s rarely used)
- Your household demand is mostly in the early evening peak window
- You’re on a complex meter setup and can’t get reliable half-hourly readings
- You need maximum simplicity and don’t want to change routines
Metering note: Many time-of-use tariffs require a smart meter providing half-hourly data. If your smart meter is in “dumb mode” (not communicating), you may not be eligible until that’s resolved.
Costs, exclusions and common pitfalls (UK-specific)
1) Standing charge differences
Even if the off‑peak unit rate looks attractive, a higher standing charge can reduce the benefit—especially for lower-usage homes.
2) Peak-time “hidden” loads
Cooking, showers (if hot water reheats after), laundry and electric showers can fall in peak. A few habits can swing the result.
3) Heat pump control setup
If controls are poorly configured (e.g., high flow temps, frequent cycling), you might not be able to shift demand without comfort issues—and efficiency can drop.
4) Eligibility and rollout changes
Suppliers can change tariff rules, availability and rates. Always confirm eligibility criteria and current prices before you commit.
5) Exit fees and contract terms
Some tariffs include exit fees or fixed terms. If you plan to switch again soon, factor this into the decision.
6) Not a like-for-like comparison
Comparing a time-of-use tariff to SVT only makes sense if you use the same annual kWh and consider when you use it.
If you rent: you can usually switch supplier if you pay the bill, but check your tenancy terms. If your landlord controls the heat pump settings, ask how hot water and heating schedules are managed before you switch to time-of-use pricing.
FAQs
Is Octopus Energy Cosy only for heat pumps?
Cosy is designed for households using an electric heat pump for space heating (and often hot water). If you don’t have a heat pump, you may still be able to take the tariff depending on current rules, but it’s usually not a good fit because the benefit relies on shifting heating load into cheaper windows.
Do I need a smart meter for a Cosy-style time-of-use tariff?
In most cases, yes. Time-of-use billing typically needs half-hourly smart meter readings. If your meter isn’t communicating, you may be billed incorrectly or be unable to join until it’s fixed, so check smart meter status before switching.
What actually makes Cosy cheaper (or more expensive)?
It comes down to your weighted average unit price: how many kWh land in cheaper windows versus peak windows, plus the standing charge. If you can shift hot water heating and some space heating to off-peak, it can reduce costs; if your household uses lots of electricity during peak, bills can rise.
Will Cosy affect my heat pump efficiency?
It can, depending on how you shift demand. Heat pumps are usually most efficient running steadily at lower flow temperatures. Aggressive stop-start scheduling or pushing very high temperatures to “catch up” can reduce efficiency. A gentle pre-heat strategy and smart hot water scheduling is often more effective.
Are Cosy rates the same across the UK?
Not always. Electricity prices can vary by region, and standing charges vary by distribution area. Your payment method and meter type can also affect what’s available. Always check prices for your postcode and compare the full tariff details.
Can I switch away quickly if Cosy doesn’t work for me?
That depends on the tariff terms. Standard variable tariffs are typically more flexible, while fixed or specialist tariffs may include a fixed term and/or exit fees. Check the supplier’s tariff information and any early exit charges before you sign up.
Is Cosy suitable if I also have an electric vehicle or home battery?
Potentially, but it depends on when the cheap windows fall and how your EV/battery schedule aligns with them. EV charging is a large flexible load and can improve outcomes on some time-of-use tariffs, but if your EV charging happens during peak (or forces peak use elsewhere), it can do the opposite.
What information should I gather before comparing Cosy with other tariffs?
Ideally: your annual electricity use (kWh), whether you have gas too, your smart meter status, and a rough idea of when you use electricity (especially heating/hot water times). If you can access half-hourly usage data, you can estimate how much demand could realistically move into off-peak windows.
If you’re struggling with bills, you can find practical support (including payment plans and grant guidance) at Citizens Advice: energy help.
How we assess whether Cosy can cut bills (methodology)
Our approach
- Answer-first: we focus on the practical decision drivers (eligibility, load shifting, rates, standing charge).
- Usage-pattern led: time-of-use tariffs are evaluated by when kWh are used, not just annual totals.
- Whole-bill view: we consider standing charges, peak rates, and the risk of “peak creep”.
Assumptions & limitations
- Example rates are illustrative and not a live tariff quote.
- Real outcomes depend on your postcode region, meter, and payment method.
- Heat pump comfort/efficiency varies by property insulation, emitter size (radiators/UFH), and control strategy.
- We don’t assume you can shift all heating—only a realistic portion (often hot water plus some pre-heat).
Editorial trust signals
- Written by
- EnergyPlus Editorial Team
- Reviewed by
- Energy Specialist
- Last updated
- June 2026
Sources & further reading (UK)
- Ofgem: information for energy consumers
- Citizens Advice: energy
- GOV.UK: get help with energy bills
- GOV.UK: Boiler Upgrade Scheme (heat pump grants)
We link to independent UK regulators/advice bodies for consumer rights, billing standards and support schemes.
Want to see if Cosy-style savings are realistic for your home?
Compare whole-of-market home energy tariffs by postcode and usage profile. If a time-of-use tariff looks promising, we’ll help you sanity-check the peak/off-peak trade-off before you switch.
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