After carrying out thousands of BER assessments, the most common question we get is "where do I start?" People know they want to upgrade, they've seen the grants, but the sheer number of options is paralysing.
The good news: there's a well-established sequence that works for almost every Irish home. Get it right and each upgrade builds on the last. Get it wrong, say, installing a heat pump before insulating, and you'll overspend on an oversized unit that has to work twice as hard in a draughty house.
Here's the order that SEAI recommends, that energy advisors agree on, and that we see deliver the best results in practice.
A BER assessment is the real starting point. Your assessor surveys your home and produces an Advisory Report that tells you exactly where heat is escaping and which upgrades will make the most difference, specific to your house, not generic advice. It typically costs €200–€350 and saves you from guessing. If you're in Dublin, Meath, Wicklow, Kildare or Louth, our parent company Homerating.ie can have an assessor out to you within days.
Insulation first, attic, then walls
This isn't glamorous, but it's where most of the heat loss is happening. We regularly assess homes where the attic has 50mm of old fibreglass, barely anything. Bringing that up to 300mm of modern insulation is a day's work and the difference in comfort is immediate. Attic insulation grants cover up to €1,300 for a semi-D, which is often 60–80% of the total cost. After the attic, tackle the walls: cavity wall insulation (€1,200 grant for a semi-D) if your home has cavities, or external/internal insulation for solid walls (grants up to €8,000). The point is to reduce heat demand first, everything after this works better and costs less because of it.
Then upgrade your heating system
The key point most people don't realise: a heat pump in a well-insulated home might only need to be an 8kW unit. In a poorly insulated home, you'd need a 12kW or 14kW unit to deliver the same comfort, and it would cost more to buy, more to install, and more to run. That's why insulation comes first. With the walls and attic done, a heat pump can be properly sized for the reduced heat load. The €12,500 SEAI grant (from February 2026) covers the unit, radiator upgrades, and a €4,000 renewable heat bonus. For many well-insulated homes, the net cost after grants is genuinely under €2,000.
Add solar PV panels
Solar panels reduce the electricity cost of running your heat pump, which matters, because a heat pump runs on electricity and your bills will go up without solar to offset it. With the €1,800 SEAI grant and 0% VAT, a typical 4kWp system costs €5,500–€7,500. The panels generate free electricity during the day, and you can sell surplus back to the grid under the Clean Export Guarantee (rates vary by supplier, but Electric Ireland pays 19.5c/kWh). Payback is typically 4–7 years. By this point your home is insulated and efficiently heated, so the solar is powering a well-tuned system rather than trying to compensate for one that's leaking energy.
Windows and doors (if needed)
The new windows and doors grant from March 2026 offers up to €5,600 for a detached home. But there's a catch, your home must already have adequate insulation (HLI of 2.3 or lower) to qualify. This is another reason to insulate first. If you've done steps 1–3, you'll almost certainly meet the HLI requirement already.
Why this order matters financially
There's a financial reason for doing it this way too, not just a technical one.
SEAI's individual grants are designed for a phased approach. You don't have to do everything at once or commit to a massive project. Insulate this year, heat pump next year, solar the year after, each one is a separate grant application and a separate payment. That's a lot easier to budget for than a €40,000 lump sum.
Many homeowners spread the cost over 2–3 years. Year 1: attic and cavity wall insulation (out-of-pocket: €500–€2,000 after grants). Year 2: heat pump (out-of-pocket: €1,500–€5,000 after grants). Year 3: solar panels (out-of-pocket: €5,500–€7,500 after grants). The government-backed Home Energy Upgrade Loan at 2.99% APR can bridge any gaps.
What a typical semi-D retrofit looks like
Here's a realistic example for a 1980s 3-bed semi-detached house, currently BER D, oil heating:
Attic insulation: Cost €2,000. Grant €1,300. You pay: €700.
Cavity wall insulation: Cost €2,000. Grant €1,200. You pay: €800.
Heat pump system: Cost €14,000. Grant €12,500. You pay: €1,500.
Solar PV (4kWp): Cost €8,000. Grant €1,800. You pay: €6,200.
Windows: Cost €15,000. Grant €3,000. You pay: €12,000.
Total cost: €41,000. Total grants: €19,800. Out-of-pocket: €21,200.
After all upgrades, the house moves from BER D to approximately B2. Heating bills drop by 50–60%. The home is worth an estimated 5% more based on the BER improvement. And ongoing energy savings of €1,500–€2,000 per year mean the remaining cost pays for itself within 10–14 years, faster if energy prices continue rising.
If you're not sure where your home currently sits on the BER scale, that's the first thing to find out. A BER assessment gives you the baseline and the Advisory Report maps out exactly which upgrades are worth doing and in what order. Book a BER assessment with Homerating.ie →
If this is a rental property, you can also deduct up to €10,000 (net of grants) from your rental income. Combined with the grants above, the government effectively covers the majority of the upgrade cost. Read our landlord guide →
Frequently Asked Questions
Can I do the upgrades in a different order?
You can, but you may not get the best results. Installing a heat pump before insulating means you'll need a bigger (more expensive) heat pump, and it'll run less efficiently. The SEAI-recommended order, insulation, then heat pump, then solar, gives you the lowest cost and highest savings.
Do I have to do everything at once?
No. The individual grant system lets you do one upgrade at a time, claiming a separate grant for each. Many homeowners spread the work over 2–3 years. The only route that requires everything at once is the One Stop Shop (deep retrofit).
What if I can only afford one upgrade right now?
Start with attic insulation. It has the best payback of any upgrade, the SEAI grant covers most of the cost, and you'll feel the difference in comfort within days. Cavity wall insulation is the next best value if your home has cavities.
See exactly what grants your home qualifies for
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