The example house
Throughout this page we'll work through the numbers for a single representative property: a 1985-built 3-bed semi-detached house in Cork suburbs, ~110m² floor area, currently BER C2, oil-fired central heating, original windows replaced once with first-generation double glazing in 2002, no insulation upgrades, ESB import-electricity tariff. Owner-occupied. The owner wants to get to B2 or better, with a heat pump if it makes sense.
The all-in worked example
| Measure | Gross cost | SEAI grant | Net to homeowner |
|---|---|---|---|
| Attic insulation top-up to 300mm | €1,400 | €1,300 | €100 |
| Cavity wall insulation (bonded bead) | €2,200 | €1,200 | €1,000 |
| Window replacement (10 windows, A-rated triple-glazed uPVC) | €8,500 | €0 (not under Better Energy Homes) | €8,500 |
| External door + back door replacement | €2,400 | €0 | €2,400 |
| Air-to-water heat pump (incl. emitter upgrade, removal of oil) | €16,500 | €6,500 | €10,000 |
| Heating controls upgrade | €900 | €700 | €200 |
| Pre/post BER assessments + admin | €350 | €50 | €300 |
| Multi-measure bundle bonus (3+ measures) | — | €300 | (€300) |
| Total | €32,250 | €10,050 | €22,200 |
Costs are 2026 Cork market rates with VAT. Rounded to nearest €100. Real quotes vary ±15–20% by contractor and exact spec.
What you get for €22,200 net
- BER moves from C2 to B2 or B1 (typical post-works rating for this fabric package + heat pump).
- Heating bill drops from ~€2,400/year (oil) to ~€1,100/year (heat pump on time-of-use electricity tariff). Annual saving: ~€1,300.
- Property value lift on a B2-rated 110m² Cork semi-D vs C2 typically runs €15,000–€30,000 (range depends on micro-market). Implicit return is positive on day one.
- Comfort gain — even surface temperatures, no draughts, lower humidity, better sound insulation from the new windows. Hard to monetise but real.
- Future-proofing — moving off fossil fuel; better positioned if and when carbon taxes rise.
The path-back maths
Annual saving of €1,300 against net spend of €22,200 = 17-year cash payback, ignoring property value uplift. Including the typical €15K–€30K BER-rating uplift on a Cork semi-D, the implicit return goes positive immediately. Most homeowners aren't holding the property 17 years to break even on heating; the implicit return is the relevant number.
Where the numbers move
- If you skip the heat pump and stay on oil: net spend drops to ~€12,500, BER moves to B3 (just), annual heating saving drops to ~€500/year — payback on cash 25+ years. Heat pump is the measure that does the heavy lifting on running cost.
- If you skip the windows: net spend drops by ~€8,500, BER drop one band, comfort gain noticeably less, heating saving slightly lower. Windows are the high-cost / low-grant measure — skipping them is the quickest way to bring the all-in down, but you give up real comfort.
- If you go One Stop Shop instead of individual measures: SEAI pays a higher headline grant (often €25,000–€35,000 across the bundle), you pay a managed-service premium (~10–15% over individual quotes), but cashflow is easier — you only pay the difference, not the full upfront.
- If your house is solid-wall (no cavity): cavity insulation is replaced with EWI at €18,000 gross / €12,000 net post-grant. Total spend rises to ~€32,000 net. Payback worse on cash; better on BER and comfort.
Cork-specific notes
- Cork city's older terraces and townhouses are usually solid-wall — EWI not cavity. Cost runs higher.
- Cork county has a higher proportion of 1970s–1990s semi-D and detached stock — cavity is the norm here.
- Heat pump installation in West Cork sometimes runs higher because of distance from main installer hubs in Cork city.
- Driving-rain-zone classifications are higher in West Cork — affects insulation product choice (see the cavity vs EWI guide).
Want help reading specific quotes? Send them in — we'll go through them.