Energy efficiency in new homes: the A rating explained

The energy certificate is that document with the colour scale (A green to G red) that many buyers glance at and few truly understand. But the difference between a G-rated and an A-rated home is not cosmetic — it is hundreds of euros a year in bills, real comfort inside the home and, increasingly, resale value. In Costa Blanca new build, energy efficiency is no longer an extra — it is a selling point.

The energy scale: A to G

The certificate measures two things: primary energy consumption (kWh/m²/year) and CO₂ emissions (kg CO₂/m²/year).

• A-B: modern new build with good insulation, aerothermal, quality windows. Consumption: 15-40 kWh/m²/year. Energy bill: €300-600/year for 80 m².
• C-D: renovated or mid-quality new build. Consumption: 40-90 kWh/m²/year. Bill: €600-1 200/year.
• E-F: homes built 1980-2006. No efficient insulation or modern windows. Consumption: 90-150 kWh/m²/year. Bill: €1 200-2 000/year.
• G: old homes without any insulation. Consumption: 150+ kWh/m²/year. Bill: €2 000+/year.

The difference between G and A can be €1 000-1 500/year. Over 10 years: €10 000-15 000 — exceeding many renovation costs.

How new build achieves it

Thermal envelope insulation

Facade: cavity walls with insulation (polystyrene, rock wool) or ETICS external systems. 6-10 cm insulation thickness. Roof: extruded polystyrene or sprayed polyurethane panels. Floor: slab or sanitary floor insulation.

High-performance windows

Frame: aluminium with thermal break (RPT) or PVC. Glass: double glazing with argon gas chamber. U-factor: 1.0-1.4 W/m²K (single glass = 5.7). Airtight seals reducing unwanted air leakage.

Aerothermal

The air-water heat pump extracts heat from outdoor air (even at low temperatures). In cooling mode, it reverses. Performance: for each kWh of electricity consumed, it produces 3-5 kWh of thermal energy (COP 3-5). Comparison: gas boiler COP ~0.9 (annual cost €800-1 200); electric heaters COP 1 (€1 200-2 000); aerothermal COP 3-5 (€300-600).

Underfloor heating

Water-based underfloor heating (fed by aerothermal) works at low temperature (30-40 °C vs 70 °C for conventional radiators). Lower temperature = lower consumption. Uniform heat distribution, no wall radiators.

Controlled mechanical ventilation

Modern homes are so airtight they need mechanical ventilation to renew indoor air without opening windows. Systems with heat recovery extract stale air and transfer its temperature to incoming fresh air — recovering up to 90 % of thermal energy.

LED lighting and efficient appliances

LED consumes 80 % less than traditional bulbs. Class-A appliances consume 30-50 % less than C-D. In new build, everything comes factory-fitted at maximum efficiency.

The impact on your bill

Concrete example for an 80 m² flat in Alicante:

• G-rated (1970s, no insulation, electric heaters): annual bill ≈ €2 200.
• D-rated (2000s, basic insulation, gas boiler): bill ≈ €1 100.
• A-rated (2025 new build, aerothermal, good insulation): bill ≈ €500-600.

Annual saving G→A: ~€1 600. D→A: ~€500-600. Over 20 years, the efficient home saves €10 000-30 000 in energy.

Efficiency as resale value

More buyers check the energy certificate as a purchase factor. A-B rated homes sell faster and at better prices than E-G. In some European markets, the price difference between A and G for the same size and location already exceeds 10-15 %. On the Costa Blanca, the trend is heading the same way.

Frequently asked questions

Is an A rating mandatory for new build?

No specific rating is mandatory, but the Technical Building Code (CTE) requires efficiency minimums that, in practice, lead most new homes to achieve B or A. It is difficult to build a new home that does not reach at least B under current regulations.

Can I improve an old home's rating?

Yes. Most effective improvements: windows (double glazing with RPT), facade insulation (ETICS or cavity fill), boiler replacement with aerothermal. These can move a G to D or C. Reaching A from an old home is very expensive — but improving 2-3 grades is cost-effective.

Is the certificate mandatory for selling or renting?

Yes. Since 2013, every home sold or rented in Spain must have a valid energy certificate. It must be shown in listings and provided to the buyer/tenant. Fines for non-compliance: €300-6 000.

How much does the certificate cost?

For a standard home (60-100 m²): €80-150. Issued by a certified technician (architect, technical architect or engineer). In new build, the developer includes it in the handover documentation.

Does efficiency affect acoustic comfort?

Yes, indirectly. Double-glazed RPT windows that improve thermal efficiency also significantly reduce external noise. An A-rated home is quieter than a G-rated one — insulation works both ways.

Are solar panels common in Costa Blanca new build?

Increasingly. The CTE requires a minimum solar contribution for domestic hot water. Many developments go further with photovoltaic panels for communal electric self-consumption. With 2 800+ hours of sunshine, Costa Blanca solar panels deliver exceptional yields.

If energy efficiency is a criterion in your purchase, explore our available properties or contact us for a personalised consultation.