The fastest way to cut heating bills is to use less heat, not just to chase a cheaper fuel. Insulation, draught-proofing and better controls reduce demand permanently, while fuel switching and a supplier change trim the cost of what is left. Below are the most effective steps, roughly in order of impact per euro spent.
1. Turn the thermostat down and zone your heating
Dropping your room thermostat by 1°C typically cuts heating energy by 5–10%. Most homes are comfortable at 18–20°C in living areas and cooler in bedrooms. Heating only the rooms you use — zoning — avoids paying to warm empty space. A timer that matches heating to when you are actually home is one of the cheapest wins available.
2. Upgrade your heating controls (grant available)
Modern controls — a smart thermostat, time and temperature zoning, and a hot-water cylinder thermostat — let you fine-tune heating instead of running the whole house at one setting. SEAI supports this:
The SEAI heating controls grant is worth €700.
Source: SEAI, 12 June 2026It is one of the least expensive upgrades to qualify for and pairs well with insulation work.
3. Insulate — the highest-impact upgrade
Insulation cuts how much heat escapes, which lowers bills every year regardless of fuel. Attic insulation is usually the best value, followed by wall insulation. SEAI grants cover a large share for a typical semi-detached home:
| Upgrade | SEAI grant (semi-detached) |
|---|---|
| Attic insulation | €1,500 |
| Cavity wall insulation | €1,300 |
Attic insulation alone can cut heat loss through the roof by a large margin in an under-insulated home. See our attic insulation guide and the full list of insulation grants for other dwelling types and rates.
4. Draught-proof
Draughts around doors, windows, letterboxes, chimneys and unused vents let warm air escape and cold air in. Draught-proofing strips, brush seals and a chimney balloon are inexpensive DIY fixes that make a noticeable difference to comfort and bills. Just keep purpose-provided ventilation (for example for open fires or gas appliances) clear for safety.
5. Compare your heating fuel cost per kWh
Different fuels cost very different amounts per unit of energy. Comparing on a cost-per-kWh basis is the only fair way to judge them:
| Fuel | Cost per kWh | Source |
|---|---|---|
| Wood pellets (bulk) | 10.25 c/kWh | SEAI |
| Natural gas | 13.00 c/kWh | SEAI |
| Kerosene heating oil (discounted) | 17.20 c/kWh | SEAI |
A few important caveats:
- These are raw fuel costs, before boiler efficiency. A gas or oil boiler at ~90% efficiency delivers slightly less useful heat than the raw figure suggests.
- A heat pump flips the maths: it runs on electricity (a higher per-kWh price) but delivers 3–4 kWh of heat per kWh of electricity, so its effective cost per useful kWh is often the lowest of all. Compare in our heat pump vs oil running costs guide.
6. Consider a heat pump
If your home is well insulated, a heat pump can be the cheapest and lowest-carbon way to heat it. SEAI grants substantially reduce the upfront cost:
The SEAI air-to-water heat pump grant is worth €6,500.
Source: SEAI, 12 June 2026A heat pump works best in a home that has already had insulation and controls upgraded — another reason to tackle those first.
7. Switch supplier and tariff
Whatever fuel you use, the supplier still matters. New-customer discounts on gas and electricity are common. Compare every plan at the CRU’s compareenergy.ie, and see our cheapest electricity guide for current rates.
Putting it together
A sensible order for most homes:
- Draught-proof and adjust controls (cheap, immediate).
- Insulate the attic, then walls (grant-supported, big impact).
- Improve your BER rating as you go.
- Once the fabric is good, consider a heat pump or fuel switch.
- Re-check your supplier tariff yearly.
Most of these upgrades attract SEAI support — check your grant eligibility before you start so you claim everything you are entitled to.