Heating, Ventilation and Renewables — Heat Pump, Underfloor, MVHR and Solar PV for an Irish Self-Build

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When this matters most

You're specifying heating and ventilation at detailed design, or retrofitting an old heating system.

When this doesn't apply

Heat pump commissioned, BER cert done, system in service.

Decision matrix

If: BER target is A2

Then: A heat pump alone (6 kW) with average fabric: possible

If: BER target is A1

Then: A heat pump + MVHR + 6 kWp solar + airtightness ≤2 m³/m²·hr

If: Passive House

Then: A heat pump + MVHR + 8 kWp solar + airtightness ≤0.6 m³/m²·hr

If: Site is rural with cheap electricity access

Then: Add solar PV for running cost. Don't oversize the battery upfront

If: Hot water demand is high (4+ bedrooms)

Then: Heat pump cylinder (300 L) or solar thermal primary

If: All-electric home required

Then: No oil, no gas — heat pump + solar PV + solar thermal

Frequently asked questions

How much does a heat pump cost in Ireland in 2026?

Air-to-water heat pump: €8,500–€15,000 installed for a 6–9 kW system. After SEAI grant (€6,500 + potential €3,500 bonus): €2,000–€8,500 net cost.

What is MVHR?

Mechanical Ventilation with Heat Recovery. Two fans, a heat exchanger. Extracts stale air from kitchen/bathroom, pulls in fresh air from outside. The heat exchanger recovers 70–90% of the heat that would otherwise be lost. A must for airtight homes.

How much does solar PV cost?

6 kWp system: €9,000–€13,000 installed (2026 prices). Check SEAI for current schemes.

Is underfloor heating worth it?

On an ICF, slab, or raft foundation with screed — yes, cheap and effective. On a suspended timber floor — yes but costs more.

What's the best BER rating I can realistically hit?

A1 with a fabric-first design and a heat pump. A1 + cost-effective: well-insulated ICF or timber frame with passive design orientation.

Sources

SEAI, Heat Pump and Solar PV Grants 2026. https://www.seai.ie/grants/

Building Regulations 2023, TGD Part F (Ventilation) and Part L (Conservation of fuel and energy). https://www.gov.ie/

NSAI, I.S. EN 16798 — Indoor environmental input parameters. https://www.nsai.ie/