Most Spanish homes are energy disasters — rated E, F, or G. Billions in EU retrofit subsidies exist. But the gap between "money is available" and "homeowner applies for it" is enormous, especially in small inland towns. This is a tool that tries to close it.
4 min read
The context
This tool came out of researching heat mortality in inland Spain. The research brief on Yecla and the Murcia region surfaced a pattern: life-saving interventions exist — cooling centres, building retrofits, vulnerability check-ins — but small municipalities lack the administrative capacity to deploy them. The EU has allocated billions through Next Generation funds for energy-efficient building retrofits. Regional governments have added their own programmes. But the money sits unclaimed because the path from "I heard there are subsidies" to "I've submitted an application" is bureaucratically impenetrable for most homeowners.
This is a familiar shape. The technology exists (insulation, heat pumps, solar panels). The funding exists (Next Generation EU, PREE 5000, regional grants, IRPF deductions). What's missing is the bridge between the two — something that says: given your specific house, here's what would help, here's what it would cost, here's what's subsidised, and here's how long until it pays for itself.
What it does
Retrofit is a bilingual (Spanish/English) tool where you enter your property details — province, year built, type, current heating, windows, insulation — and get back:
- An estimated energy rating (A through G) based on construction year, climate zone, and building characteristics. Most pre-2006 Spanish homes land somewhere between D and G.
- Three recommended improvements ranked by impact, with cost ranges, estimated annual savings, available subsidy amounts, payback periods, and CO₂ reduction.
- Available subsidy programmes — Next Generation EU, PREE, IRPF tax deductions, and regional grants for Murcia and Valencia — with links to official application portals.
- A printable report you can take to a contractor or energy assessor.
Everything runs client-side. No data leaves your browser. No accounts, no tracking.
What it doesn't do
It doesn't replace a professional energy audit. The energy rating is an estimate based on typical building characteristics for your construction period and climate zone — not a measurement. The cost ranges are market averages for Spain in 2024-2025. Your actual situation will vary.
But that's not really the point. The point is orientation. Most homeowners don't know their house is probably rated F. They don't know that replacing single-glazed windows in a 1970s Yecla apartment could save them €400-600 a year. They don't know that the EU will cover 40-80% of the cost. The tool's job is to make that visible — to turn vague awareness into specific, actionable information.
The local angle
Spain has one of the oldest housing stocks in Europe. The vast majority of residential buildings predate the 2006 Código Técnico de la Edificación (CTE), which introduced the first meaningful thermal efficiency requirements. Everything built before that is, thermally speaking, a sieve.
Inland towns like Yecla (correctly mapped in the tool as climate zone D3 — continental, despite Murcia province being coastal B3) experience both summer extremes above 40°C and winter temperatures that regularly drop below freezing. These aren't just comfort issues. Heat kills elderly residents every summer. Cold drives energy poverty every winter.
The subsidies exist precisely for this. But the people who need them most — elderly homeowners in small towns, people with limited digital literacy, people who've never heard of "Next Generation EU" — are the least likely to navigate the application process. A tool that says "you're eligible for €6,000 towards insulation, here's the link" is a small step. But it's a step.
Try it
retrofit.willworth.dev — available in Spanish and English. Enter your property details and see what's available. Takes about two minutes.
This is part of the Avenues of Investigation series — mapping domains where technology and funding exist but deployment lags. See also: desalination, rare disease diagnosis, hearing aids, soil, and pharmacogenomics.