CAE in a home renovation offer: what to check before assigning energy savings

Neutral editorial AI-generated illustration of a wooden house model, two blank sheets and a turquoise paperweight on a table; not an actual project, a CAE certificate or evidence of energy savings or payment.

A homeowner on the Costa Blanca is comparing offers for energy-efficient renovation. One quote includes a line labelled “CAE benefit” next to the price, with consent to transfer energy savings in an annex. Before treating the offer as cheaper, it is worth understanding exactly what you are being asked to sign. Work on the home and assignment of an associated right are not the same undertaking by the contractor.

This article helps you prepare questions before agreeing to such an arrangement: who is involved, which savings are transferred, what the owner receives in return and which conditions continue after the renovation. It does not establish a particular property’s eligibility for CAEs, calculate income, taxes or payback, or provide a universal contract. Technical applicability and legal consequences require individual assessment.

1. Separate CAEs, the building’s energy certificate and the works contract

Real Decreto 36/2023 defines a CAE as electronic recognition of annual final-energy savings resulting from an energy-efficiency measure. The system distinguishes the end user, the owner of the savings and the holder of the CAE itself. The savings owner may be the person who invested in the measure or the recipient of assigned savings; a sujeto obligado or sujeto delegado holds the CAE. Owning the apartment therefore does not, on its own, explain every role.

A CEE under Real Decreto 390/2021 contains information about a building’s energy characteristics, its rating and recommendations. It is a different document. In practical discussions, do not use “energy certificate” interchangeably for a CEE, a future CAE and an installer’s document. Ask for each document’s full name and a separate explanation of its purpose.

Start with three lines: the works being purchased, the document about the home’s characteristics being discussed, and the assignment being proposed. If the offer only uses a general term such as “paperwork”, what is included remains unknown. Clarify this before comparing the final price. A CAE clause does not confirm the quality of the future installation, and a CEE does not tell you to whom the savings from the new measure have been promised.

2. Establish who is entitled to decide on the assignment

Identify the parties involved in the order: the property owner, the actual investor, the customer commissioning the works and the person signing the annex. They may be the same person, but this must be established rather than assumed. If someone else, an organisation or several parties are paying, ask a professional to explain who owns the savings and on what basis. Do not sign someone else’s declaration simply because the apartment’s address is yours.

For a measure affecting the building’s common areas or systems, the task is more complex than for an individual order. The comunidad’s representative, the contractor and an individual apartment owner do not become interchangeable parties. Before signing, clarify whose decision and what scope the document concerns. This article does not establish voting majorities, the president’s powers or how proceeds should be distributed among neighbours.

If a representative is acting, separately check whether their authority covers this particular assignment and its associated obligations. You should not interpret authority to organise ordinary renovation work as permission for any additional agreement. The practical outcome of this stage is an identified signatory with a clear role, not a collection of signatures “just in case”.

3. Understand who receives the savings and who is responsible for the consideration

MITECO’s official FAQ distinguishes a convenio CAE with a participant in the system from a private assignment contract with an intermediary; it also explains traceability of the chain and the limit on the number of intermediaries. The consideration must be clearly defined: money or specified non-monetary consideration with an equivalent in euros per kWh. It must be clear whether estimated savings or the final certified quantity is used, with the unit price maintained. This is a brief reference to the FAQ, not a promise of a particular payment.

Ask for the full details of your contractual counterparty and an explanation of its role. The company sending the offer, the installation company and the purchaser of the savings may be different entities. Who exactly must provide the promised consideration? Who should answer questions about an unclear amount or condition? A familiar logo on the first page is no substitute for these answers.

If an intermediary refers to a future participant, request an explanation of the subsequent chain and the evidence relating to your measure. Do not ask for access credentials to someone else’s account. What you need is an understandable account of the parties and documents for the specific offer, not access to all of the contractor’s systems. A missing explanation is, for now, an open question, not automatically a proven breach.

4. Link the assignment to a specific measure in the home

Article 11 of Orden TED/815/2023 provides for information in the convenio about the parties, the measure and its location, actual or estimated annual savings, consideration and useful life. It also identifies an obligation to keep the measure active and a declaration that no other convenio has been signed for the same measure. Once signed, the savings pass to the system participant. Applying for CAE issuance and obtaining a favourable verification are separate stages, not automatic consequences of signing.

Check that the annex covers the same scope as the estimate: which equipment is being replaced, in which apartment and which works are included. If one document concerns a single installation and another several measures, ask for the boundaries to be explained. Do not accept an expanded subject matter simply because the annex still contains a familiar address.

Check previous offers and signed annexes for this renovation. The question is not how many companies sent prices, but whether the same savings have been promised to different recipients. Do not sign a repeat declaration from memory. If the contractor has changed, give the professional the earlier wording so that its status can be clarified before a new agreement is made.

5. Read the price, method of provision and conditions separately

Write down exactly what is promised to the owner: a money transfer, a credit within the agreed arrangement or another specified outcome. Then find where the method and timing of provision, the responsible party and the documents allowing the result to be checked are stated. Do not treat an advertising phrase such as “renovation compensation” as an adequate explanation of the obligation.

If the amount depends on final certified savings, ask to see how that dependence is expressed in the text and how you will be informed of the final value. Do not calculate it yourself from a reduction in your household electricity bill. Changes in weather, occupancy and tariffs do not turn a domestic comparison into a result established by the system.

Ask what happens if verification identifies missing documents or the result differs from the preliminary estimate. Which obligations concerning the renovation remain, who prepares clarifications and what happens to the promised consideration? Do not invent an answer such as “the customer always pays extra” or “the contractor guarantees everything”. The specific conditions need to be examined; this article establishes neither a universal payment deadline nor the acceptability of every clause.

6. Check aid and subsidies against the particular programme

Article 14 of Orden TED/815/2023 excludes from a CAE application measures that have received aid financed by the Fondo Nacional de Eficiencia Energética, and requires information about public support requested or received. The FAQ explains general compatibility with other programmes and, where a compatible subsidy is involved, a limit on combined proceeds equal to the investment cost. This does not mean that every combination of aid is permitted for your property.

List your actual applications and decisions: programme name, authority, application status and funding relating to the works. “There is no subsidy yet” can mean different things: no application has been made, it is under consideration, or it has been approved but not paid. Do not replace these different states with a single negative answer in a declaration.

Ask a professional to compare the programme’s rules and funding source with the proposed assignment. Do not relinquish aid already granted on the strength of a brief promise of a more profitable CAE. This article does not compare the financial outcomes of the two options or instruct you how to withdraw from aid. Unknown compatibility must remain a condition to clarify before deciding.

7. Discuss obligations after the renovation is finished

The annex may address keeping the measure active throughout the specified useful life. Clarify exactly what this means for your order and what would be required following a breakdown, replacement of equipment or subsequent changes to the home. Do not equate that period with the manufacturer’s warranty: these are different matters, even when both are expressed in years.

If you plan to sell the apartment or hand it over to another user, ask in advance about the consequences for the agreement already signed. Do not infer either automatic termination of obligations or automatic transfer of all conditions to the buyer merely from the sale. Ask which documents and explanations should be provided for a legal assessment of the specific case.

Do not promise the contractor to retain an unknown configuration without reading the wording. For example, an owner may also be discussing a later renovation stage that changes some equipment. Disclose this circumstance before signing so that the parties do not base the offer on different assumptions about the apartment’s future use.

8. Agree on the information needed before removal work begins

Ask the responsible party to identify in advance the information about the existing and future condition needed for the chosen verification route. If the old equipment is removed, it may be too late to discover that an accessible identification marking or document was not preserved. However, do not open an appliance or approach dangerous structures to take a photograph: a competent contractor should organise the collection of technical data.

Separate the information you actually have from assumptions. An old sale listing does not always describe the system actually installed. Do not substitute a similar model or someone else’s apartment to fill a field. Ask for an explanation of an acceptable way to establish missing information, without promising a favourable verification outcome in advance.

Send personal and property information to the agreed recipient and only to the extent needed. Do not send a complete financial dossier to every company that supplied a price. An owner’s working list can link each requested document to its purpose and recipient; this is a means of control, not a new mandatory CAE-system form.

9. Compare offers without a hidden assignment

When comparing options, first make the works themselves comparable: scope, equipment and promised services. Then state on a separate line whether assignment of the savings is included and what reciprocal terms are proposed. Do not rank offers solely by the prominent total figure if one involves purchasing works while another also requires you to accept obligations associated with transferring a right.

Ask how the elements of the offer are reflected in the contract and billing documents. Refer the tax aspect to a competent professional: this article does not determine a rate, tax base or the obligations of a particular recipient. Calling something a “discount” in advertising is no substitute for analysing the substance of the transaction.

Before agreeing, try to answer in your own words: who is assigning the savings, to whom, for which measure, in return for what and with which continuing conditions? If the answer amounts to “the installer will handle everything”, the subject matter is not yet clear enough. A properly prepared assignment does not guarantee income or CAE approval; it is an informed decision about specific wording, distinct from choosing equipment and paying for ordinary renovation work.

Official sources and limits of the review

The sources were read on 31 October 2026. MITECO’s FAQ is marked as updated on 9 October 2026 and expressly warns that it has no legal force. The specified definitions and articles were read, not all technical sheets or the conditions of every subsidy. Brief source-derived information is separated from editorial questions for the owner. Eligibility of a particular renovation, assignment price, tax consequences and actual payment have not been established.

MITECO: questions about the CAE system, assignment of savings, consideration and compatibility with aid.

BOE: Real Decreto 36/2023, definitions of participants and CAE verification and issuance procedures.

BOE: Orden TED/815/2023, articles 11 and 14 on the convenio CAE and the application for issuance.

BOE: Real Decreto 390/2021, definition of the building energy certificate, CEE.