🏚️ Home Energy Upgrade
Which energy upgrade is worth doing first?
Everyone selling home upgrades has a reason theirs should be first. The order that actually pays is usually the opposite of the order they are sold in: the cheap, unglamorous measures return far more per euro than the expensive, visible ones.
Figures reviewed September 2026. Free, no signup, nothing stored on our servers.
What this means
Payback here is net cost after grant divided by estimated annual saving. It is a blunt measure and it deliberately ignores comfort, which is often the real reason people are glad they did the work — but it is the right way to decide what to do first when the budget is finite.
Attic and cavity insulation almost always top the list, because they cost very little, attract grants, and cut a meaningful share of the heating bill. They are also the measures nobody is knocking on your door about.
Savings do not add up. Insulating the attic after insulating the walls saves less than it would have on its own, because the bill it is saving a share of has already shrunk. The ranking applies each measure to your remaining bill rather than adding the percentages together, which is how upgrade calculators usually overstate the total.
What affects the result
- What the house is built of. Cavity walls can be filled cheaply; solid walls cannot.
- What is already done. The savings shown are of your current bill, which falls as you improve.
- How you heat the house now, and at what efficiency.
- Grant eligibility. SEAI conditions vary by measure, and some require the house to predate a certain year.
- Whether you qualify for the Warmer Homes Scheme, which is free for eligible households.
- How warm you actually keep the house. Many households take part of the benefit as more comfort rather than a lower bill.
Which energy upgrade is worth doing first?
Why the cheap measures win
Payback is cost divided by saving, and insulation has a very small numerator. Attic insulation at a net cost of a few hundred euro saving a couple of hundred a year pays back in two or three. External wall insulation saving more in absolute terms still takes far longer because it costs twenty times as much. Neither is wrong to do — but with a limited budget, the order matters enormously.
Before a heat pump
SEAI requires a technical assessment confirming the house meets a heat loss standard before it will grant a heat pump, and that is the fabric work above. The heat pump calculator shows why: at a low seasonal efficiency, running costs can exceed the boiler it replaced.
What this does not measure
Comfort, damp, draughts, noise and the BER rating, which affects what a house sells or rents for. Households that insulate frequently report that the house is warmer rather than the bill being lower — they took the benefit in comfort. That is a real return and it is not in the payback figure.
Important assumptions
Every figure on this page rests on these. Where one does not match your situation, the answer moves — sometimes a great deal.
- Savings are expressed as a percentage range of your annual heating bill, based on typical performance for each measure in a house that has not already had it done.
- Measures are ranked individually against your current bill. Doing several reduces the saving from each one, so do not add the figures together.
- Grant amounts are indicative. SEAI publishes current amounts and conditions and they change — check before budgeting.
- Costs are typical Irish market ranges for a standard three-bed semi-detached house, and will differ for larger or unusual properties.
- Solar PV is listed but not costed against the heating bill, because it reduces the electricity bill instead. It is costed properly in the solar payback tool.
Official sources
Where this tool applies a published rule, this is where the rule comes from. Check the source before acting on anything that matters.
- SEAI — home energy grants
Current grant amounts and eligibility conditions for insulation, heating controls, heat pumps and solar.
- SEAI — Warmer Homes Scheme
Fully funded upgrades for households receiving certain welfare payments — no cost to the homeowner.
- SEAI — One Stop Shop service
The route for a whole-house upgrade managed end to end, with a higher combined grant rate.
- SEAI — Building Energy Rating
How to get your own house assessed rather than working from typical figures.
Common questions
What is the best home energy upgrade to do first in Ireland?
Attic insulation, in almost every house that has not had it. It is the cheapest measure, it is grant-aided, it takes a day, and it typically cuts 10–20% off the heating bill. Cavity wall insulation is usually second where the walls have a cavity.
Can I get a grant for insulation?
Yes. SEAI pays fixed grant amounts for attic, cavity, internal and external wall insulation, subject to conditions including the age of the property and the use of a registered contractor. Households on certain welfare payments may qualify for the fully funded Warmer Homes Scheme instead.
Are new windows worth it for energy savings?
Rarely on energy alone — the payback is usually measured in decades. Windows are worth replacing for comfort, noise, draughts, condensation and the state of the existing frames. Judge them on those and treat the energy saving as a bonus.
Should I do a whole-house upgrade at once?
SEAI's One Stop Shop route offers a higher combined grant rate for deeper retrofits done together, and it avoids doing the same work twice. It also requires a much larger up-front budget. For most households a staged approach starting with insulation is more realistic, and the ranking above is the order to stage it in.
What to check next
Would a heat pump cost me less to run?
Your current heating cost against a heat pump at realistic Irish efficiencies and prices.
Heat Pump SavingsNewWill solar panels pay for themselves?
Generation, self-consumption, export income and payback over 10, 15 and 20 years.
Solar Payback CalculatorWhat grant can I get for solar?
Current SEAI grant amounts for solar PV and what they leave you to pay.
SEAI Solar GrantPopularAm I paying too much for electricity?
Compare Irish electricity and gas tariffs on net first-year cost, not headline rate.
Energy Switch ComparisonNext steps across CheckIreland
Picked for what you just worked out — not a list of everything we make.
CheckIreland is independent and is not affiliated with the Irish Government or any public body. This tool is general information built on published rules and typical costs — it is not financial, tax or legal advice, and it does not account for your individual circumstances. Confirm anything that matters with the relevant body or a qualified adviser before acting on it.