The heat wave burns me and I need to turn on the air conditioning: how do I save on the electricity bill?

To establish a legal obligation regarding the minimum (or maximum) air conditioning temperature in homes at the state level in Spain, it is essential to approve a regulation with the rank of law. This can be achieved through various means (government bill, parliamentary bill proposal, autonomous communities' initiative, popular legislative initiative, or even a royal decree-law in cases of extraordinary and urgent need). In all cases, except for the decree-law, the regulation passes through the Congress and Senate and is only binding when it is sanctioned, promulgated, and published in the Official State Gazette (BOE).

Initiative routes to create the legal obligation

The obligation could be incorporated into a new law or an existing one (for example, regulating energy, housing, or consumer protection). The main routes are:

• Government bill: the Council of Ministers approves the preliminary draft, converts it into a bill, and submits it to the Congress. This is the most common and fastest route when the Executive promotes the measure.
• Parliamentary group or deputies' bill proposal: one or more groups in the Congress or a minimum number of deputies present a drafted text introducing the obligation.
• Autonomous Assemblies' bill proposal: an autonomous chamber can send a state bill proposal on this matter to the Congress, which will follow the ordinary procedure there.
• Popular legislative initiative (ILP): citizens could promote a bill proposal, meeting constitutional requirements (signature collection, admissibility control, etc.), to set temperature limits in homes.
• Royal decree-law: the Government could immediately establish the obligation through a decree-law, but only if there is a situation of extraordinary and urgent need. This instrument is approved by the Council of Ministers and comes into force after its publication in the BOE, but must later be ratified by the Congress.

Parliamentary procedure in the Congress of Deputies

Except in the case of the decree-law (which is not an ordinary law procedure), the essential steps in the Congress are:

• Submission and qualification: the Congress Board admits the bill or proposal for processing and orders its publication.
• Consideration (only for bill proposals): the Plenary decides whether to "take into consideration" the initiative. If rejected, it lapses; if accepted, the ordinary procedure continues.
• Amendment period: a period opens for groups to submit amendments to the text (to the whole, with alternative text, and to the articles). Here, for example, the temperature range, exceptions for vulnerable people, sanctioning regime, etc., could be debated.
• Committee drafting: in the competent committee, a drafting group is appointed to study the text and amendments and draft a committee report with a proposed text.
• Committee: the committee debates the report and surviving amendments and approves a opinion. In some laws, the committee has full legislative competence; in others, the text goes to the Plenary.
• Congress Plenary: final debate on the opinion and reserved amendments. The entire text is voted on. If approved, the Congress sends the bill to the Senate.

Procedure in the Senate

In the Senate, the law follows a similar scheme, although usually more agile:

• Reception and publication of the text sent by the Congress.
• Amendments and, if applicable, veto: senators and groups can submit amendments to the articles, and the Senate Plenary can approve a veto (returning the text to the Congress).
• Committee and Plenary: an opinion is issued, and the Plenary votes on the amendments and, if proposed, the veto.

If the Senate approves amendments, the text returns to the Congress, which decides whether to accept or reject them. If the Senate issues a veto, the Congress can lift it by an absolute majority in a first vote or by a simple majority after two months have passed.

Final phase: law in force and enforceability

Once the Congress and Senate have completed their intervention, the text is definitively approved as law. The final steps are:

• Sanction and promulgation by the King, at the Government's proposal.
• Publication in the BOE, the moment when the law becomes official and public.
• Entry into force, usually after 20 days (vacatio legis) unless the law itself provides a different period.

Only from that moment would the legal obligation regarding air conditioning temperature in homes be legally enforceable. Usually, the law itself would also empower the Government to issue regulations (royal decrees or orders) that specify technical and control aspects, but the fundamental "jump" of creating the obligation necessarily goes through this parliamentary process with the rank of law.

The Institute for the Diversification and Saving of Energy (IDAE) is a public business entity attached to the Ministry for the Ecological Transition and the Demographic Challenge, through the Secretary of State for Energy. According to its Statute, its central competence is to propose, adopt, and execute guidelines and measures for energy saving, efficiency, and diversification. In practice, it has become a key technical actor in Spanish energy policy: it designs and manages large aid programs, promotes renewable energies, coordinates projects with European funds, and generates information and studies that guide decision-making. Its role is both as an executing body of the energy transition and as a public think tank specialized in energy.

Institutional framework and legal basis

The agreement between the CIS and IDAE published in the BOE recalls that the Institute is a public business entity attached to MITECO, organizationally dependent on the Secretary of State for Energy, responsible for government policy on climate, energy, and environment (CIS–IDAE agreement).

In that same text, Article 3 of Royal Decree 18/2014, which approves the IDAE Statute, is cited, attributing it the competence to:

• Propose, adopt, and execute guidelines, measures, and studies necessary to achieve an adequate level of conservation, saving, and energy diversification in the industrial, agricultural, and service sectors.
• Carry out any type of activities and services both with public administrations and companies as well as with private entities and companies to fulfill these purposes ([link]).

The 2024 delegation of competencies resolution also shows how the exercise of these functions is internally organized: the presidency (held by the Secretary of State for Energy) is the competent body to grant subsidies managed by the Institute and can delegate to the General Directorate the resolution of aid in various programs. This architecture reinforces IDAE's role as the operational arm of the Secretary of State.

Functional competencies: from regulation to execution

In recent years, IDAE itself has emphasized in its institutional campaigns that it is a technical reference body in designing energy efficiency policies and a promoter of renewable energies, as well as a manager of European and national funds for the energy transition and decarbonization (40 years of IDAE campaign, commemorative seal).

Based on information from the BOE, IDAE itself, and coverage by Demócrata, its practical competencies can be grouped into several blocks:

• Design and management of aid programs: the Institute acts as the managing body of large subsidy lines linked to the Recovery Plan and FEDER or Next Generation EU funds. It manages calls for energy storage, innovative renewable and hydrogen projects (large hydrogen valleys, energy storage) and programs for clean industrial technologies like Renoval 2 (Renoval 2).
• Granting and monitoring subsidies: the 2024 delegation resolution specifies that the presidency and, by delegation, the General Directorate issue resolutions granting subsidies and their modifications, applying the regulatory bases of each program ([link]).
• Promotion of self-consumption and efficiency: IDAE launches massive campaigns to promote renewable self-consumption and energy saving, with messages aligned with the PNIEC 2023-2030 objectives (energy transformation campaign, self-consumption campaign).
• Generation of knowledge and support for policy formulation: the agreement with CIS for the “Energy Transition Barometer 2025-2026” fits with the statutory mission of producing studies that guide public policies (energy transition barometer, Demócrata news).
• International cooperation and observatories: the Iberian Energy Observatory, created together with the Portuguese agency Adene, is an instrument to monitor and disseminate information on energy transition and efficiency in the peninsula (Iberian Energy Observatory).
• Participation in forums and support for innovative ecosystems: the Institute presents itself as a pioneer actor in renewable energies and innovative business models, joining the National Forum of Emerging Companies to bring energy policy closer to entrepreneurship (Emerging companies forum).

Role in Spanish energy policy

Demócrata highlights that the management of large energy transition and electrification programs “falls on the Institute for the Diversification and Saving of Energy, an entity dependent on the Ministry” (transition and electrification aid). The Independent Authority for Fiscal Responsibility places IDAE as one of the main managers of Recovery Plan funds, with nearly 4.8 billion mobilized (AIReF analysis).

Overall, IDAE acts as:

• Executor of energy policy, transforming Government decisions and regulations (royal decrees of regulatory bases, ministerial orders) into concrete calls, subsidies, and projects on the ground (Order TED/765/2024).
• Technical advisor, providing studies, data, and analyses that feed plans like PNIEC, energy PERTEs, and reindustrialization and decarbonization strategies (green reindustrialization, MITECO note).
• Interface with the private sector and citizens, both through mass communication campaigns and through specific forums, observatories, and financial support to companies and innovative projects.

For all these reasons, IDAE has consolidated itself as a structural piece in the architecture of the Spanish energy transition, linking political design from MITECO with practical implementation in territories, companies, and homes.

In Spain, electricity supply contracts can apply different prices according to the time slot as long as they respect the framework of the electricity sector (especially the Law 24/2013 of the Electricity Sector) and the specific regulation of regulated prices, tolls, and charges. Essentially, the retailer must base its offer on the period structure set by regulation (tolls and charges), correctly measure or profile consumption by periods, and provide the customer with prior information and clear, comparable invoices. Additionally, recent regulations reinforce transparency, limit unilateral modifications, and specifically protect vulnerable consumers and beneficiaries of the social bonus.

Basic applicable regulations

The general framework is established by Law 24/2013 of the Electricity Sector, which sets the regime for supply, marketing, the social bonus, and basic consumer information and protection obligations.

For contracts with domestic consumers and small consumers, the following are especially relevant:

• Royal Decree 216/2014 (PVPC and contracting regime, partially in force and modified by Royal Decree 469/2016).
• CNMC Circular 3/2020 and its modification by Circular 1/2025, which define the methodology for transport and distribution tolls by hourly periods.
• Royal Decree 148/2021 (electric system charges) and annual charge orders such as Order TED/1312/2022, Order TED/1487/2024, and Order TED/1524/2025.
• Resolution of March 18, 2021 (CNMC), which sets the specific values of tolls by periods.
• Resolution of April 28, 2021 and the previous one of May 23, 2014, which establish the minimum content and model of the electricity invoice.
• Resolution of June 24, 2021 and its modification of October 6, 2022, on QR codes and access to the CNMC's offer comparator.
• Order TED/456/2021, which regulates the price information that retailers must provide.
• Royal Decree-law 23/2021, which introduces reinforced transparency obligations in retail markets and consumer protection.
• Annual resolutions on consumption profiles for points without hourly registration, such as those of 2023, 2024, and 2025, which refer to the Measurement Points Regulation.

Requirements on price structure and measurement

To apply different prices by time slot, the contract must be based on a period structure consistent with the tolls and charges defined in Circular 3/2020, Royal Decree 148/2021, and their developments (toll resolutions and charge orders). This means that:

• The energy term billed to the customer must be associated with periods (peak, flat, valley, etc.) defined by regulation, although in the free market more periods can be added as long as they are transparent.
• There must be hourly measurement through a smart meter; when there is no hourly record (type 4 and 5 points), the consumption profiles set in the cited annual resolutions apply.

Transparency, prior information, and billing

From Law 24/2013, Royal Decree 216/2014, and Royal Decree-law 23/2021, it follows that, for offers with time discrimination, the contract must clearly contain:

• Definition of each time slot and its specific schedule (including holidays and weekends when applicable).
• Price per kWh and, if applicable, specific fixed terms per period, differentiating the regulated part (tolls and charges) from the energy part.
• Conditions for price revision or update and limits to unilateral modification, with sufficient prior information.

Invoice regulation (2014 and 2021 resolutions) and CNMC QR codes require that the consumer can easily identify:

• The breakdown of energy, tolls, charges, and other concepts.
• Consumption and cost by time period, when the meter allows it.
• A QR code or link leading to the official offer comparator, facilitating comparison of contracts with and without time discrimination.

Protection of vulnerable consumers and other aspects

The cited charge orders and Law 24/2013 regulate the social bonus and the cost of supply for certain vulnerable consumers. Supreme Court rulings from 2016 (October 24 ruling, October 25 ruling) emphasize the need for the social bonus financing regime to be compatible with European law but do not alter the possibility of offering time discrimination; they do reinforce that the design of these contracts must respect the protection framework for vulnerable consumers.

In summary, any contract with prices by time slot must: follow the regulated structure of periods and tolls, correctly measure or profile consumption by periods, provide prior, clear, and verifiable information on schedules and prices, reflect that information in the invoice in a detailed manner, and respect specific rules for consumer protection, especially vulnerable consumers and social bonus beneficiaries.