Designing for BER A1 in Ireland — Fabric First, Heat Pump, and What the BER Assessor Measures
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BER A1 needs wall U-value 0.13–0.18, roof 0.13–0.16, floor 0.13, airtightness 1–3 m³/m²·hr, and a heat pump.
Designing for BER A1 in Ireland means getting the fabric right and pairing it with a heat pump. The numbers: wall U-value 0.13–0.18 W/m²K (Part L 2022 backstop is 0.18; A1 typically needs 0.13–0.16), roof 0.13–0.16 (backstop 0.16; A1 typically 0.13), floor 0.13, airtightness 1–3 m³/m²·hr at 50 Pa (Passive House is ≤0.6), and a heat pump (6–9 kW air-to-water, depending on the floor area and fabric). The BER assessor measures: floor area, U-values, airtightness (blower door test), and the heating system. Inputs go into the DEAP (Dwelling Energy Assessment Procedure) calculation. Fabric first: invest in insulation and airtightness before spending on heating. A well-insulated house lets you size the heat pump 6 kW smaller, saving €1,500–€3,500 on the heat pump itself and €300–€500/year on running cost.
TL;DR
BER A1 needs wall U-value 0.13–0.18 W/m²K, roof 0.13–0.16, floor 0.13, airtightness 1–3 m³/m²·hr at 50 Pa, and a heat pump.
Fabric first: invest in insulation and airtightness before spending on heating. A well-insulated house lets you size the heat pump 6 kW smaller.
The BER assessor measures: floor area, U-values of walls/roof/floor/windows, airtightness (blower door test), and the heating system. Inputs go into the DEAP calculation.
When this matters most
You're at design stage and need to target BER A1.
When this doesn't apply
You're aiming for a lower BER (A2, A3) for cost reasons.
Frequently asked questions
What U-value do I need for BER A1 in Ireland?
Wall 0.13–0.18 W/m²K, roof 0.13–0.16, floor 0.13, windows 0.8–1.2. Airtightness 1–3 m³/m²·hr at 50 Pa. Plus a heat pump (6–9 kW air-to-water).
How much does it cost to design for BER A1?
Adds €5,000–€15,000 to the wall insulation cost over a Part L 2022 backstop build. Saves €3,000–€5,000 on the heat pump size. Lifetime saving: €5,000–€15,000 on energy and capital cost over 20 years.
What is the DEAP calculation?
Dwelling Energy Assessment Procedure. The Irish method for calculating BER. Inputs: floor area, U-values, airtightness, heating system. Output: energy use and CO2 emissions, mapped to a BER rating A1–G.
Sources
SEAI, BER and DEAP guidance. https://www.seai.ie/
Building Regulations 2023, TGD Part L (Conservation of fuel and energy — Dwellings). https://www.gov.ie/
Frequently asked questions
What U-value do I need for BER A1 in Ireland?
Wall 0.13–0.18 W/m²K, roof 0.13–0.16, floor 0.13, windows 0.8–1.2. Airtightness 1–3 m³/m²·hr at 50 Pa. Plus a heat pump (6–9 kW air-to-water).
How much does it cost to design for BER A1?
Adds €5,000–€15,000 to the wall insulation cost over a Part L 2022 backstop build. Saves €3,000–€5,000 on the heat pump size. Lifetime saving: €5,000–€15,000 on energy and capital cost over 20 years.
What is the DEAP calculation?
Dwelling Energy Assessment Procedure. The Irish method for calculating BER. Inputs: floor area, U-values, airtightness, heating system. Output: energy use and CO2 emissions, mapped to a BER rating A1–G.
When this matters most
You're at design stage and need to target BER A1.
When this doesn't apply
You're aiming for a lower BER (A2, A3) for cost reasons.
Where to go next
Branch into
Adjacent decisions at the same stage.