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.
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.
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
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Watch out for
Common mistakes, hidden costs, gotchas.