If you are comparing tariffs, switching options, and bill-control tactics, start with the Energy Bills and Switching Hub for the full decision framework.
Energy bills are one of the biggest household expenses — and many people don’t understand why theirs are so high. This guide explains the main reasons for expensive energy bills and how to reduce them.
Read more: See our Energy Grants guide for a complete overview of this topic.
Understanding Your Energy Bill
Your bill consists of:
| Component | What It Is |
|---|---|
| Unit rate (p/kWh) | Cost per unit of gas or electricity used |
| Standing charge (p/day) | Daily fixed charge regardless of usage |
| Usage (kWh) | How much energy you actually consumed |
| VAT (5%) | Tax on domestic energy |
Your bill = (Unit rate × kWh used) + (Standing charge × days) + VAT
Top Reasons Your Bill Is High
1. You Use More Energy Than Average
The “typical” household figures used by Ofgem are:
- Electricity: 2,700 kWh/year
- Gas: 11,500 kWh/year
If you exceed these, your bill exceeds the typical amount.
High usage factors:
- Larger home with more rooms to heat
- Older, poorly insulated property
- More people living at home
- Working from home
- Electric heating (no gas)
- Electric vehicles charging
- Energy-hungry appliances (old fridge, tumble dryer)
- Higher thermostat setting
2. Your Property Is Poorly Insulated
Heat escapes through:
- Walls (up to 35% of heat loss)
- Roof (25%)
- Windows and doors (15-20%)
- Floors (10%)
- Draughts (15%)
An EPC rating of E, F, or G means your home is very inefficient. You could be paying £500-1,500 more per year than a well-insulated property.
3. Estimated Bills Were Wrong
If your supplier has been estimating:
- They may have underestimated your usage
- Now actual readings show the truth
- You owe a “catch-up” amount
Check if your bills show “E” (estimated) or “A” (actual).
4. Unit Rates Have Increased
Energy prices change when:
- Ofgem updates the price cap (quarterly)
- Your fixed deal expires (moved to expensive SVR)
- Wholesale energy markets rise
Compare your current unit rates to previous bills to see if rates increased.
5. Your Fixed Deal Ended
Fixed tariffs eventually expire. When they do:
- You move to Standard Variable Tariff (SVT)
- SVT is usually more expensive
- You should switch to a new deal before expiry
Check your bill for tariff name — is it what you signed up for?
6. Standing Charges Have Risen
Standing charges increased significantly in recent years:
- Now ~50-60p/day electricity
- ~30-35p/day gas
- Combined: ~£300/year before using any energy
You pay this even if you use zero energy.
7. Heating to Higher Temperatures
Every degree higher on your thermostat increases heating costs by ~10%.
| Thermostat Setting | Relative Cost |
|---|---|
| 18°C | Baseline |
| 19°C | +10% |
| 20°C | +20% |
| 21°C | +30% |
| 22°C | +40% |
The recommended temperature is 18-21°C.
8. Inefficient Appliances
Old appliances use more electricity:
| Appliance | Old Model | Modern Efficient |
|---|---|---|
| Fridge-freezer | £80/year | £35/year |
| Washing machine | £45/year | £25/year |
| Tumble dryer | £120/year | £50/year |
| TV (plasma) | £50/year | £15/year (LED) |
Appliances rated A or higher cost less to run.
9. You’re on a Poor Tariff
Not all tariffs are equal. Check:
- Are you on standard variable (usually most expensive)?
- Are there cheaper fixed deals available?
- Does your tariff reward gas/electric combo?
Compare deals on Uswitch, Compare the Market, or Money Supermarket.
10. Your Boiler Is Inefficient
Boilers rated below A waste gas:
- G-rated boiler: 70% efficient (30% wasted)
- A-rated boiler: 90%+ efficient
Replacing an old boiler could save £300-500/year.
How to Check Your Bill
Step 1: Understand What You’re Paying
Find on your bill:
- Unit rate (electricity): Currently ~22-25p/kWh under price cap
- Unit rate (gas): Currently ~6-7p/kWh under price cap
- Standing charge: Electricity ~53p/day, Gas ~31p/day
- Total kWh used this period
Step 2: Compare to Average Usage
| Household Size | Electric (kWh/year) | Gas (kWh/year) |
|---|---|---|
| 1-bed flat | 1,800 | 7,500 |
| 2-bed flat | 2,500 | 9,500 |
| 3-bed house | 3,000 | 12,500 |
| 4-bed house | 4,000 | 15,000 |
| 5-bed house | 4,500 | 18,000 |
If your usage is much higher, investigate why.
Step 3: Check for Estimates
Look for “E” (estimated) vs “A” (actual) readings. If all estimated, submit actual readings now.
Step 4: Get a Smart Meter
Smart meters:
- Send readings automatically
- No more estimates
- Show real-time usage
- Help identify waste
Request free installation from your supplier.
How to Reduce Your Energy Bill
Quick Wins (Free)
- Lower thermostat by 1°C — Saves ~10%
- Submit actual meter readings — Stop overpaying estimates
- Switch off standby — Saves £55/year average
- Only boil water you need — Kettles waste energy
- Wash at 30°C — Modern detergents work fine
- Draught-proof doors — DIY foam strips cost £10
- Close curtains at dusk — Reduces heat loss
Medium Investments (£50-500)
- LED bulbs throughout — 80% less than incandescent
- Smart thermostat — Optimise heating schedule
- Radiator reflector panels — £20-30, saves heat escaping through walls
- Draught-proofing — Windows, doors, letterbox
- Cylinder insulation jacket — £15-25, pays back in months
Bigger Investments (£500+)
- Loft insulation — £300-500, saves £200-300/year
- Cavity wall insulation — £500-1,500, saves £150-300/year
- New boiler — £2,000-4,000, saves £300-500/year
- Double/triple glazing — £4,000-10,000, saves £100-200/year
- Solar panels — £5,000-10,000, saves £300-500/year
Government Grants
Check if you qualify for:
- ECO4 scheme — Free insulation for eligible households
- Warm Home Discount — £150 off electricity bill
- Boiler Upgrade Scheme — £7,500 grant towards heat pump
- Great British Insulation Scheme — Free/subsidised insulation
Switching Supplier
When to Switch
- Fixed deal about to end
- On expensive standard variable tariff
- Better deals available elsewhere
- Moving home
How to Compare
- Go to comparison site (Uswitch, MSE, Compare the Market)
- Enter postcode and current usage
- Compare annual costs
- Check exit fees from current tariff
- Switch online — takes 17-21 days
Fixed vs Variable in 2026
| Factor | Fixed | Variable (Capped) |
|---|---|---|
| Price certainty | Yes, locked in | Changes quarterly |
| Exit fees | Usually yes | No |
| Better when prices fall? | No, locked higher | Yes, follows cap down |
| Better when prices rise? | Yes, protected | No, rises with cap |
If You Can’t Afford Your Bills
Payment Support
- Warm Home Discount: £150 off (apply Sept-March)
- Cold Weather Payments: £25/week in very cold weather
- Winter Fuel Payment: £200-300 for pensioners
- Household Support Fund: Council discretionary help
Payment Plans
Contact your supplier if struggling:
- Request payment plan
- Ask about hardship funds
- Discuss prepayment meter options
- Avoid debt — priority bill
Priority Services Register
Free extra support if:
- Elderly
- Disabled
- Chronically ill
- On medical equipment
Register with your supplier for priority help during outages.
Related Guides
- Complete UK Energy Guide — All about energy
- Help Paying Energy Bills — Financial support
- Energy Price Cap Explained — How the cap works
- Warm Home Discount Guide — £150 off
- Should I Fix My Energy? — Tariff decisions
High energy bills are often fixable. Check your usage, submit real meter readings, improve insulation where possible, and switch to a better tariff. If you’re struggling to pay, contact your supplier immediately — they must offer support.