BER Target and Heating System in Ireland — Match the Heat Pump to the Fabric
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BER A2: 6 kW heat pump. BER A1: 6 kW + MVHR + 6 kWp solar. Passive House: 6 kW + MVHR + 8 kWp solar + airtightness ≤0.6.
BER target drives the heating system spec in Ireland. BER A2: 6 kW heat pump + average fabric + airtightness 3–5. BER A1: 6 kW heat pump + MVHR + 6 kWp solar + airtightness 1–2 m³/m²·hr. Passive House: 6 kW heat pump + MVHR + 8 kWp solar + airtightness ≤0.6. Sizing: 6 kW for a fabric-first 150 m² house (wall 0.13, roof 0.13, floor 0.13). 9 kW for less insulated. Oversize wastes money. Match the heat pump to the fabric, not the other way around. A 9 kW heat pump in a fabric-first house runs short cycles and is less efficient. The BER assessor calculates the heat load from the floor area, the U-values, and the airtightness. Engineer sizes the heat pump based on the heat load.
When this matters most
You're at design stage and need to match the heating system to the BER target.
When this doesn't apply
The heating system is commissioned.
Sources
SEAI, BER and DEAP guidance. https://www.seai.ie/
Frequently asked questions
What size heat pump do I need for BER A1?
6 kW for a fabric-first 150 m² house (wall 0.13, roof 0.13, airtightness 1–2). 9 kW for less insulated. Engineer sizes based on the heat load calculation.
What heating system do I need for Passive House?
6 kW heat pump + MVHR + 8 kWp solar + airtightness ≤0.6 m³/m²·hr. The whole system is designed around the airtightness and the fabric.
What is a fabric-first design?
A design that prioritises insulation, airtightness, and thermal bridges over the heating system. A fabric-first house needs a smaller, cheaper heat pump and runs it more efficiently.
When this matters most
You're at design stage and need to match the heating system to the BER target.
When this doesn't apply
The heating system is commissioned.
Where to go next
Next decision
The next step in your build sequence.
Branch into
Adjacent decisions at the same stage.
- Battery Storage in Ireland 2026 — Cost, Payback, and When to Skip It →
- Biomass Boiler in Ireland — Wood Pellet Stove, Cost, SEAI Grant, and When It Beats a Heat Pump →
- District Heating in Ireland — Where It Exists, the Connection Cost, and When It Works →
- Ground Source Heat Pump in Ireland — Borehole Cost, When It's Worth the Premium →
- Solar Thermal in Ireland — Hot Water from the Sun, When It Pays Back, and the Alternatives →
Watch out for
Common mistakes, hidden costs, gotchas.
- Battery Storage in Ireland 2026 — Cost, Payback, and When to Skip It →
- Biomass Boiler in Ireland — Wood Pellet Stove, Cost, SEAI Grant, and When It Beats a Heat Pump →
- District Heating in Ireland — Where It Exists, the Connection Cost, and When It Works →
- Ground Source Heat Pump in Ireland — Borehole Cost, When It's Worth the Premium →
- SEAI Heat Pump Grant 2026 — €6,500 + €3,500 Bonus, Eligibility, and the BER Trap →
- Heat Pump in Ireland 2026 — Air-to-Water Cost, SEAI Grant, and the 6 vs 9 kW Question →
- MVHR in Ireland — Mechanical Ventilation with Heat Recovery, Cost, and Why You Need It →
- Radiators vs Underfloor Heating in Ireland — Cost, Comfort, and Heat Pump Pairing →
- Solar PV in Ireland 2026 — 6 kWp Cost, Payback, and the SEAI Grant →
- Underfloor Heating in Ireland — Cost, Floor Build-up, and the Heat Pump Pairing →
Compare with
Alternative approaches worth knowing.