Financiación y Economía de la Eficiencia Energética

Global investment in building energy efficiency reached 237 billion USD in 2022, 16% higher than in 2021, according to the World Energy Investment Report by the IEA (2023). Despite this growth, the figure represents only 60% of the level needed to align the sector with the net zero emissions trajectory by 2050: the IEA estimates that annual investment must reach 400 billion USD by 2030. The geographical distribution reflects disparities: Europe leads with 40% of global investment (driven by the Renovation Wave Strategy and post-COVID recovery funds), followed by China (25%), North America (20%), and the rest of the world (15%). In the EU, the energy renovation rate of the building stock remains at 1% annually (out of 220 million existing buildings), compared to the 3% annually needed to achieve full stock decarbonisation by 2050, according to the European Commission.

The gap between current and required investment is explained by documented financial barriers: information asymmetry (the owner is unaware of the potential savings and perceives the investment as a risk), split incentives (the owner pays for the retrofit but the tenant reaps the savings: this affects 40% of the rental housing stock in the EU), credit access restrictions (construction SMEs and low-income households lack borrowing capacity), and payback periods perceived as long (> 10 years for deep envelope retrofits). The economics of energy efficiency is grounded in the concept of life cycle cost (LCC): an analysis over 30-50 years that integrates the initial investment cost, annual operating costs (energy, maintenance), equipment replacement costs, and residual value. Studies by the BPIE (Buildings Performance Institute Europe) demonstrate that deep retrofits (demand reduction ≥ 60%) have lower LCC than non-intervention when horizons of 30+ years are analysed, with an average IRR (internal rate of return) of 6-12%.

The Recovery and Resilience Facility (RRF), endowed with 672.5 billion EUR (grants and loans), is the main public financing instrument for energy efficiency in the EU. Spain received an allocation of 69.5 billion EUR, of which component 2 (Housing rehabilitation and urban regeneration plan) has 6.82 billion EUR earmarked for energy retrofitting. The programme channels aid through the autonomous communities, with grants of 6,300-18,800 EUR/dwelling for envelope retrofitting (insulation, windows) and 1,900-3,000 EUR/dwelling for thermal system upgrades. The target is the energy retrofit of 510,000 dwellings and 1,230 public buildings by 2026. As of June 2023, 120,000 applications had been processed and 45,000 actions completed, placing the execution pace below the planned trajectory.

The European Commission's LIFE Clean Energy Transition programme (2021-2027 budget: 1 billion EUR) finances technical assistance, training, and capacity-building projects for energy efficiency. The European Investment Bank (EIB) allocated 16.4 billion EUR to building energy efficiency projects during 2015-2022, with preferential financial terms (interest rate Euribor + 0.5-1.5%, repayment period 15-25 years). In Spain, the ICO (Instituto de Credito Oficial) offers the ICO Green credit line with fixed rates from 4.5% APR for energy efficiency investments of up to 12.5 million EUR per client. Income tax deductions for energy retrofitting (approved by Royal Decree-Law 19/2021) allow deductions of 20% of the investment (maximum 5,000 EUR) for actions that reduce heating/cooling demand by 7%, or 40% (maximum 7,500 EUR) for reductions of 30% in non-renewable primary energy.

Green bonds dedicated to building energy efficiency exceeded 50 billion EUR in cumulative issuance in Europe in 2023 (Climate Bonds Initiative). The EU green taxonomy (Regulation 2020/852) sets the technical screening criteria: for a building renovation to qualify as a sustainable activity, it must demonstrate a reduction in primary energy demand of ≥ 30% or achieve an efficiency level corresponding to class A on the energy performance certificate. Green bonds certified under the EU Green Bond Standard (EUGBS) — regulation adopted in November 2023 — require that at least 85% of funds be allocated to taxonomy-aligned activities, with verification by an external auditor accredited by ESMA.

Energy Service Companies (ESCOs) finance energy efficiency measures and are remunerated from the generated savings, eliminating investment risk for the property owner. The most widespread contractual model is the energy performance contract (EPC), regulated in Spain by RD 56/2016: the ESCO finances and implements the measures, and the owner pays an annual fee equal to or less than their previous energy bill for 7-15 years; at the end of the contract, all savings revert entirely to the owner. The European ESCO market reached 28 billion EUR in 2022 (JRC, 2023), with Germany (8.4 billion), France (5.2 billion), and Italy (3.8 billion) as the leading markets. Green mortgages (Energy Efficient Mortgages, EEM) offer preferential terms (reduction of 0.10-0.30 percentage points in the interest rate) for dwellings with an energy rating of A or B: the EeMAP (Energy Efficient Mortgages Action Plan) project, led by the European Mortgage Federation, demonstrated in a sample of 70,000 mortgages that energy-efficient dwellings have a default rate 30% lower than conventional ones.

The return on investment in energy efficiency varies according to the type of intervention and the building's starting point. Interventions on systems (replacement of an oil boiler with an aerothermal heat pump, lighting renewal to LED, installation of variable frequency drives on pumps and fans) have the shortest payback periods: 2-5 years, with IRR of 15-30%. Replacing a 100 kW oil boiler (efficiency 85%, fuel cost 0.08 EUR/kWh) with an aerothermal heat pump (average COP 3.5, electricity cost 0.15 EUR/kWh) reduces operating costs by 50-60%: from 9,400 EUR/year to 4,300 EUR/year, yielding savings of 5,100 EUR/year on an investment of 18,000-25,000 EUR, resulting in a payback period of 3.5-4.9 years.

Interventions on the building envelope (ETICS facade insulation, window replacement, roof insulation) have longer payback periods (8-15 years) but achieve greater demand reductions (40-70%) and a longer improvement service life (30-50 years). A study by IDAE (2020) on 50 retrofitted buildings in Spain quantified that comprehensive envelope retrofitting (ETICS with 80-120 mm EPS, double-glazed windows with thermal break, roof insulation) reduces heating demand by 50-65% in CTE climate zones D-E, with an average investment of 150-250 EUR/m² of treated facade and a payback period of 10-14 years without subsidies, reduced to 5-8 years with PRTR grants. The combination of envelope and systems interventions (deep renovation) achieves reductions of 60-80% in primary energy consumption, with an IRR of 6-10% over 30 years and a positive NPV from year 12-18. The financing and economics of energy efficiency, analysed with methodological rigour, demonstrate that retrofitting the building stock is a profitable medium-term investment whose main barrier is not economic but informational and institutional.