For years, carrying out energy-efficiency improvements on a home meant applying for cumbersome government grants, submitting mountains of paperwork, and waiting up to two or three years to receive the funds.
With the entry into force of the Sistema de Certificados de Ahorro Energético (CAE) regulated by the Real Decreto 36/2023, the model has taken a 180-degree turn in Spain. CAEs are not public subsidies as such, but a private market mechanism where energy companies and oil companies (Obligated Subjects) pay in cash the final energy savings (kWh) you achieve in your home to comply with their legal decarbonization quotas.
The result is simple: the energy savings from your home are converted into liquid money or an immediate discount on your bill.
However, to be able to convert the cold air that no longer enters your home into cash, there is an indispensable technical and administrative pillar: Energy Efficiency Certificate (CEE).
The Energy Performance Certificate (EPC): The Essential Cornerstone.
It is not possible to apply for a CAE or receive a single euro without providing documentation showing how much energy the home consumed before the renovation and how much it consumes afterward. This is where the Energy Efficiency Certificate (CEE)—issued by a qualified professional (architect, construction manager, or engineer) and officially registered with the autonomous community—becomes mandatory.
To monetize the renovation, a two-phase process is required:
- 1. Initial Energy Efficiency Certificate (PRE): Measures the initial state of the property. Reflects the energy demand, type of insulation, quality of windows, and performance of old heating/ACS systems.
- 2. Final Energy Efficiency Certificate (POST): After completing the work, the technician audits the property again and issues a new registered CEE that formally demonstrates the energy performance improvement or reduction in kWh/m² per year.
Double economic benefit: A Final Energy Efficiency Certificate (POST) demonstrating a significant reduction in energy demand or consumption not only opens the door to claiming the CAE payment but is also the legal document required by the tax authority to apply the IRPF deductions (between 20%, 40% or up to 60%) in the income tax return.
Procedure and Requirements: A Step-by-Step Guide to Applying for a CAE
To benefit from the CAE system through the standardized sheets of the Official Catalog of the Ministry for Ecological Transition (MITECO), the intervention must follow a strict technical sequence:
- Step 1. Initial CEE (PRE): Registro oficial del estado energético antes de la reforma.
- Step 2. Execution of the Work: Installation with an accredited company and collection of evidence (sheets and photos).
- Step 3. Final CEE (POST): Registration of the new certificate that justifies the reduction in consumption.
- Step 4. CAE Settlement: Emission of the certificates and payment in cash or discount on the bill.
Requirements you must meet before you start
- Right of use: Be the owner or an authorized tenant of the property.
- Competent technician: Hire a registered professional for the preparation of the CEEs (PRE and POST).
- Accredited companies and installers: The work or installation must be carried out by a company that provides the technical certificates of the installation, technical sheets of the materials and detailed invoices.
- Measures of the Standardized Catalog: The renovation must fit within the sheets approved by the MITECO (building envelope insulation, window replacement, heat pump, etc.).
Step-by-Step Process for Application
- PRE Audit and Initial CEE: The CEE is drafted and registered before touching a single brick or window. This document sets the baseline for consumption.
- Execution of the Work and Collection of Evidence: During installation, the company collects the technical sheets of the product (e.g., frame/glass transmittance, CE marking of cellulose or SCOP of the heat pump), quality labels, and photographs of the process (essential for the technical file).
- Emission and Registration of the Final CEE (POST): Once the work is completed, the technician issues the new CEE with the achieved improvement and registers it with the Autonomous Community's Industry/Energy Council.
- Validation and Settlement with the Delegated Subject: The installing company or a Delegated Subject (accredited CAE manager) consolidates the file with invoices, photos, certificates, and CEEs. Once verified by an external body accredited by ENAC (Energy Saving Verifier), you receive the incentive or a direct discount on your final bill.
Practical Examples: Energy Savings and Return through CAEs
1. Thermal Insulation with Cellulose (Blowing or Blown): Insulating air chambers or attics with cellulose (recycled paper fiber and boric salts) is the intervention with the highest percentage return per euro invested, thanks to its great ability to delay the entry of heat in summer and prevent leaks in winter.
- Role of the CEE in this measure: The CEE PRE calculates the losses through the building envelope. When blowing cellulose, the CEE POST reflects a drastic drop in the demand for heating and cooling in kWh/m²year.
- CAE Return: As this is a purely passive and highly efficient measure, the standardized insulation sheet grants a high volume of CAEs. In many roofs or attics, the CAE incentive covers between 60% and 90% of the total cost of the cellulose.
2. Window Replacement with High-Performance Carpentry: Replacing old closures with single glazing or aluminum without thermal bridge (RPT) with high-end PVC or aluminum profiles with double/triple low-emissivity glass.
- Role of the CEE in this measure: The technician inputs the thermal transmittance (U) and solar factor of the old windows versus the new ones. The CEE POST certifies the reduction in overall energy consumption of the property.
- CAE Return: The calculation is done per square meter renovated and climate zone. Depending on the geographic location and improvement in transmittance, the homeowner receives between 40 € and 130 € of discount or credit for each m² of window replaced.
3. Aerothermal System Installation (Air-to-Water Heat Pump):Replacing an inefficient oil, natural gas, or electric boiler with a high-efficiency aerothermal system for heating, cooling, and Sanitary Hot Water (ACS).
- Role of the CEE in this measure: Eliminating the use of fossil fuels significantly improves the CEE POST rating, typically raising it to an “A” or “B” for CO₂ emissions and non-renewable primary energy consumption.
- CAE Return: Given that thousands of kilovolt-amperes of fossil fuels are replaced by renewable aerothermal energy, the CAE amount for a single-family home or apartment usually ranges between 1,200 € and 3,500 €, charged upon completion of the installation.
Summary of the Process and Its Economic Return
| Efficiency Measure | Required Document | CEE POST Benefit | CAE Economic Impact |
|---|---|---|---|
| Cellulose Insulation | CEE PRE/POST + Cellulose Technical Data Sheet + Construction Photos | Sharp Drop in Demand for Air Conditioning (kWh/m²) | Covers up to 60%–90% of the project |
| Window Replacement | CEE PRE/POST + CE Marking of Windows and Thermal Label | Improvement in Thermal Transmittance (U) of the Building Envelope | Incentive of 40 € to 130 € per m² Renovated. |
| Aerothermal System Installation | CEE PRE/POST + RITE Certificate + Technical Sheet (SCOP > 3.5) | Elimination of fossil fuels and CO₂ emissions | Between 1,200 € and 3,500 € of direct charge/credit. |
Conclusion: Turn Your Renovation Into a Profitable Asset
The CAE system has changed the rules of the game in energy-efficient building retrofitting in Spain. There is no longer a need to wait years for uncertain subsidies: if the renovation is planned correctly from the start with a PRE Energy Efficiency Certificate, a qualified installation company, and a POST CEE closing certificate, the generated energy savings are immediately translated into money in your pocket.