energy performance at near-passive scale

"Energy-efficient home" has become an industrial term, yet it floats. A specific target needs to sit behind it — for instance Hungary's mandatory class BB minimum (effective January 2024 for new-build residential), or our own stricter near-passive target. On the SIP homes we deliver, we measure 60–70 kWh/m²/year in annual primary energy demand — that's class BB+, and close to the passive-house threshold of 50 kWh/m²/year.

the five layers that determine performance

Energy performance is never a single product. We coordinate five layers to reach the target:

thermal bridges: where the math is decided

A home's energy class is not decided by the average U-value but by thermal bridges. A thermal bridge is a local point where insulation continuity breaks — a balcony slab tying into the structure, a window-frame connection, the slab-wall junction. A poorly designed thermal bridge can erode 8–12% of the theoretical energy performance.

In SIP homes, thermal bridges are inherently fewer — no mortar joints, no reinforced-concrete-wall junctions. The remaining ones (slab-wall, window-frame) are controllable through careful design and weekly site supervision. That weekly review is therefore not optional; it is mandated.

heat pumps: a sensitivity to efficiency

An air-source heat pump's COP (Coefficient of Performance) tells you how many kWh of heat it produces per kWh of electricity. The market average is 3.5; with the heat load of a good SIP home and properly designed low-temperature underfloor heating, 4.0–4.5 is achievable. The impact is direct: 4.5 COP cuts the electricity bill by 28% versus 3.5 for the same indoor temperature.

4.2average COP

solar: not always the win

An 8–10 kWp solar array can produce 90–110% of an average family home's annual electricity demand. Annually — but in winter (November to February) production drops to 20–30% of capacity, exactly when heating demand peaks. Gross annual balance is not the same as monthly bill balance. Battery storage (10–15 kWh) improves the situation but is expensive; Hungary's state-supported net-metering scheme (VHR) is currently the most common answer.

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The passive-house target lives not in a single product but in the proportions of the five layers. One weak layer drags the whole chain down.

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airtightness: the invisible exam

Hungary's n50 ≤ 1.0 1/h airtightness threshold underpins the stricter energy classes. It means that under 50 Pa pressure differential, the home's air volume exchanges at most 1.0 times per hour. Typical measured values on our SIP homes: 0.4–0.6 — twice better than the requirement; on traditional brick: typically 1.5–2.5.

We measure airtightness with a Blower Door test — on every SIP home, twice: at the end of construction (before finishes), and before handover. If the value worsens between the two readings, we localise the leak and fix it before handover.

summary

Energy performance isn't won by one choice but by coordinating five layers. The SIP structure gives an advantage — low U, few thermal bridges, good airtightness — but the openings, ventilation, heat pump, and solar each can boost or break the total. We commit to the target (class BB+ or passive-house) in writing at the first consultation, and we measure it before handover.