Regulatory · Data centres > 1 MW
The draft Spanish Royal Decree on energy efficiency and sustainability for data centres, transposing Directive (EU) 2023/1791, requires developers and owners of facilities above 1 MW of total nominal energy input to file a Heat Reuse Plan (PAC) and its Cost-Benefit Analysis (ACB). The document is filed at project stage, together with the building permit and the grid access application.
willbö writes the full PAC-ACB to the technical and economic depth the autonomous community's energy-efficiency authority needs to issue a favourable report.
01 / Framework
The PAC-ACB is the binding document that determines whether the asset's waste heat must be recovered, and on what terms. If the ACB comes out favourable and the authority ratifies it, a legally enforceable implementation calendar kicks in — one that affects the asset's operation and its definitive grid access.
02 / Services
Each workstream covers one principle of Annex I. The five together ship as a single coherent PAC-ACB, fit for filing with the autonomous community's energy-efficiency authority. The senior team that signs the document is the same one that runs the project from kick-off.
Detailed inventory of the data centre's waste-heat sources, broken down by IT systems and by cooling circuits (air, water, hybrid liquid-cooling). Determination of temperatures, flows, and projected operating hours. Seasonal modelling with annual thermal load curves, sized for the evacuation infrastructure.
Justified definition of the system's geographic boundary. Identification of existing and potential thermal-demand points in the surrounding area, in three layers: public secondary sources (cadastre, urban planning, MITECO data); formal activation of the Art. 5.4 mechanism by which the local authority must provide heat-demand data; quantification of demand scenarios tied to district-heating network projects.
Comparative analysis between the no-reuse base case and the viable alternatives. For each alternative we cover the thermal recovery base, commercial maturity, integration complexity with the data centre's cooling architecture, and the availability of proven industrial solutions. Water-to-water heat pumps, heat-recovery chillers, dual-evaporation systems, and direct integration with district-heating networks are all on the table.
Economic-financial model built on traceable assumptions. CAPEX, OPEX, discounted cash flows, residual value, and decision criterion per Annex I. Extended with the valuation of CO₂ emissions avoided, systemic energy savings, and external benefits. Sensitivity analysis on the critical variables: energy price, investment level, and thermal demand absorbed.
Identification and assessment of administrative, planning, and financial barriers to the reuse system. For each barrier, concrete corrective measures. Roadmap from favourable ACB ratification to system commissioning, with the regulatory deadlines under Art. 5.12 (3 voluntary + 2 mandatory years) and the intermediate control points.
Synthesis document aimed at the corresponding municipality, translating the ACB conclusions into terms readable for municipal decisions on district-heating projects. Useful when waste-heat reuse from the data centre can catalyse the development of a heat network in partnership with the local administration.
03 / Process
The standard schedule embeds a mid-point review in week four, focused on validating the key economic assumptions before the analysis is closed. The pattern adapts to the client's milestones and to the administrative filing windows.
04 / Clients
Organisations whose digital infrastructure planning sits above the regulatory threshold and needs to clear the PAC-ACB with the technical quality the authority demands.
Large-scale campus operators with individual or aggregated assets above the regulatory threshold.
Infrastructure groups and contractors developing new data centres for outsourcing or own use.
Backbone nodes, telecom processing centres, and edge installations of relevant size.
Academic and research centres with high thermal density and continuous power consumption.
Banking, energy, industry, and public administration with own facilities above the threshold.
District heating operators assessing data-centre integration as a thermal source.
05 / Team
Engineering boutique based in Vigo, specialized in thermal systems, waste-heat recovery, and economic analysis of energy infrastructure. Lean senior team — the person who signs the document is the one who runs the project.
Offer engineering for the Tagus Park innovation complex DHC system in Lisbon, on direct mandate from Ferrovial Servicios. We know the architecture of a heat network from the inside — from the basic flowsheet to plant rooms and pipe routing.
Tagus Park · Lisbon · 2018
Energy efficiency and optimization study for the Galician Supercomputing Centre (CESGA), a facility functionally analogous to a high-density data centre. In-house development of CAPCO2 CO₂ capture, where thermal integration of waste heat is structural to the economic case.
CESGA · CAPCO2 · 2024–2025
Senior capacity in financial analysis of energy projects, infrastructure asset valuation, and strategic consulting. The CAPEX-OPEX-DCF model at the core of the ACB is built with the traceability and sensitivity the energy-efficiency authority requires to issue a favourable report without observations.
20+ years on energy projects
Direct line
The data centre's energy characterization is the first step of the PAC-ACB and the one that most constrains the rest of the analysis. A 30-minute call is enough to scope the engagement at a fixed price.