Direct answer: Class A for housing in Portugal is defined by the Energy Certification System (SCE), regulated by DL 101-D/2020 (which transposed EU Directive 2018/844). The certificate is issued by a certified assessor recognised by ADENE after calculating energy needs in official software and any site inspection. For new housing, the certificate is mandatory before the issuance of the use licence. A turnkey Passive House modular home typically achieves Class A — certification is integrated into the process by the builder. Typical cost €300-650, timeline 2-4 weeks after works are completed.
"Class A" is one of the most used expressions in the Portuguese property sector — and one of the least well understood. Many buyers assume that "Class A" is a subjective or marketing label. It is technical regulation: it results from an official calculation in ADENE software under DL 101-D/2020, by which the building is mandatorily classified on a 7-level scale (A+, A, B+, B, C, D, E, F) based on two quantitative indicators.
This article explains the official process step by step, with the real figures, timelines and costs. For the technical comparison with Passive House, see Class A vs Passive House. For the European Passive House standard, see Passive House in Portugal.
What SCE officially is in Portugal
The Energy Certification System for Buildings (SCE) is the Portuguese application of the revised European Directive 2010/31/EU (now 2018/844/EU). Regulated by DL 101-D/2020 (updates in 2022 and 2024), it has three objectives:
- Classify all new buildings on an objective energy scale (A+ to F).
- Impose minimum requirements on new and refurbished buildings.
- Inform buyers and tenants about the energy performance of the property.
The SCE certificate is mandatory:
- Before the use licence of any new build.
- Before sale or rental (advertised in the listing and delivered at the deed).
- After refurbishment works that significantly alter energy performance.
- In public buildings above a certain area (1,000 m² in general, 250 m² in public buildings with frequent attendance).
Validity: 10 years for housing (since 2022).
How the energy class is calculated (two indicators)
For housing (REH buildings — Regulation on the Energy Performance of Residential Buildings), the class is defined by the ratio R = Ntc / Nt between:
- Ntc: actual energy needs of the building (kWh/m²·year) — calculated in official software from the construction characteristics (thermal envelope, openings, ventilation, lighting, equipment).
- Nt: reference energy needs for a building with the same geometric characteristics and location but meeting only the minimum legal requirements.
The resulting scale:
| Class | Ntc/Nt ratio | Interpretation |
|---|---|---|
| A+ | ≤ 0.25 | Building that consumes ≤ 25% of the reference |
| A | 0.26 to 0.50 | Consumes 26-50% of the reference |
| B+ | 0.51 to 0.75 | Consumes 51-75% of the reference |
| B | 0.76 to 1.00 | Consumes the same as the legal minimum |
| C to F | > 1.00 | Consumes more than the legal minimum (only in old buildings without works) |
For new buildings, the minimum legal class currently required is Class B (DL 101-D/2020, with 2024 revision). Class A or higher is a voluntary choice by the builder — and this is what differentiates high-efficiency construction.
How a Passive House modular home achieves Class A from the start
The modular Passive House panel-frame combines 7 technical characteristics which, taken together, guarantee Class A — often A+ — in the SCE calculation:
- Continuous insulation 250-300 mm (λ ≤ 0.035 W/m·K): wall U-value ≤ 0.15 W/m²K vs legal minimum 0.35-0.45.
- Low-emissivity triple-glazed openings: U ≤ 0.8 W/m²K vs legal minimum 2.0-2.5.
- Airtightness n50 ≤ 0.6 h⁻¹ (blower door test): > 10× better than REH standard.
- MVHR-RC (ventilation with heat recovery ≥ 85%): recovers most of the extracted energy.
- No structural thermal bridges (continuous panel-frame).
- Solar thermal panels for DHW (mandatory by law, but generously sized).
- 100% LED lighting and A+++ class equipment.
In a typical SCE simulation, a T2 Passive House modular 145 m² achieves Ntc/Nt ≈ 0.20-0.32 — clearly Class A+ or Class A.
Official process: from project to certificate issuance
- Project stage: the thermal project (one of the mandatory specialities under RJUE) is calculated in ADENE software and attached to the permitting file. It provides the estimated prior certification.
- During the works: the builder executes according to the project, with photographic records of critical layers (insulation, sealing, installations).
- End of works — blower door test: field airtightness measurement. Result must be ≤ 0.6 h⁻¹ for Passive House, ≤ 3.0 for standard Class A.
- Certified assessor inspection: an assessor recognised by ADENE (public list at
adene.pt) visits the building, verifies construction vs project, measures any additional parameters, and uploads the data to the official software. - Certificate issuance: ADENE processes and issues the certificate within 5-10 working days after submission. The document is digital and has a unique QR code.
- Delivery to the owner: certificate delivered before the use licence, displayed in sale/rental advertising.
Typical cost for housing up to 200 m²: €300-650, depending on assessor and complexity. Total timeline after works are completed: 2-4 weeks.
How to choose the certified assessor (ADENE list)
The choice of assessor is up to the owner (not imposed by the builder), except in turnkey contracts where the builder provides one. Selection criteria:
- Official ADENE list:
adene.pt → Energy Certification → Certified Assessors. Search by district. - Qualification: engineer, architect or technician qualified with validated ADENE training.
- Experience with Passive House buildings: fewer than 5% of assessors have real experience with high-performance envelopes; for a Passive House modular home, choose an assessor with a track record.
- Price: €300-650 is the normal range. Prices below €250 are suspicious (the certificate may be estimated without a rigorous inspection).
- Reputation: ask the assessor for references from previous works.
In an Ecoimport Wood turnkey contract, the Class A SCE certificate is included in the price — we provide a partner certified assessor.
Real benefits of Class A (financial and non-financial)
Financial:
- Energy bill 50-70% lower than Class B/C: 400-900 kWh/year vs 2,500-4,500 kWh/year (T2 180 m²). Typical saving €60-130/month.
- Resale premium of +8-15% over Class B/C buildings of equivalent area.
- Easier to finance — some banks offer a reduced rate for Class A/Passive House housing (BPI, Novo Banco in 2026).
- Specific IRS deductions for urban rehabilitation for Class A in covered zones.
- Eligibility for support programmes (Environmental Fund, Efficiency Voucher) in some situations.
Non-financial:
- Stable thermal comfort (interior 21-25°C throughout the year without permanent AC).
- Superior indoor air quality (MVHR filters PM2.5, pollen, controlled humidity).
- Superior indoor acoustics (dense envelope).
- Significantly reduced environmental footprint.
- Superior structural durability (dry, ventilated envelope, no condensation).
Class A vs Passive House: the critical difference
Frequent confusion: Class A ≠ Passive House. They are two distinct standards:
- Class A (Portuguese SCE): Ntc/Nt ratio ≤ 0.50. Defines performance relative to the Portuguese legal minimum. It is a regulatory classification.
- Passive House (German PHI): heating demand ≤ 15 kWh/m²·year, n50 ≤ 0.6 h⁻¹. Defines absolute performance independent of location. It is a voluntary construction certification.
Every certified Passive House is Class A in Portugal; not every Class A is Passive House. Ecoimport Wood's modular home is built to the Passive House standard — the SCE certificate issued reflects the resulting Class A or A+. To go deeper, see technical comparison Class A vs Passive House.
Guaranteed Class A by contract (not just a promise)
In a serious turnkey contract, Class A should be a binding contractual clause, not indicative. Elements to require:
- Specification of the minimum class in the contract (e.g. "guaranteed Class A or higher").
- Documented blower door test before certificate issuance.
- Delivery of the SCE certificate before the deed or handover of keys.
- Contractual penalty if the final class is lower than guaranteed (e.g. refund of part of the price or corrective works at the builder's cost).
- Option of formal Passive House certification (PHI) as an add-on, if the client wishes.
This is one of the 12 essential clauses detailed in turnkey contract.
Figures and procedures indicative for the Portuguese market. Each project is assessed individually according to specific conditions.
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