Social Infrastructure Impact Investment Index (SI4) by PlusValue is entering market validation as Europe seeks to close its €150bn annual affordable housing investment gap.
Developed by PlusValue with Milliman, IFAB and IOBE, the tool links social performance to financial outcomes, generating decision-ready indicators for PPPs, blended finance, social bonds and portfolio management. Its next phase will focus on calibration, AI/ML modelling and SaaS scale-up by 2027. Sign up to the tool’s presentation on June 22, 2026 (link below).
Europe has a housing crisis and a capital problem. The affordable housing investment gap stands at €150bn per year. Political commitment is finally there – a European Affordable Housing Plan, a Housing Task Force, a Pan-European Investment Platform. But commitment alone doesn’t close the gap.
Two things are still missing: a credible investment case for affordable housing as an asset class, and the accountability mechanisms to ensure that when capital does arrive, it actually serves the communities it’s supposed to.
SI4 was built to solve both
SI4 – the Social Infrastructure Impact Investing Index – links the social performance of affordable housing and social infrastructure investments to their financial outcomes. Not as a reporting exercise. As a working analytical engine that produces decision-ready indicators for investment structuring, PPP design, social bond development, blended finance and portfolio management.
It was developed by PlusValue with Milliman (actuarial science and quantitative financial modelling), IFAB – the International Foundation Big Data and Artificial Intelligence for Human Development, and IOBE – the Foundation for Economic and Industrial Research, with support from the European Commission. It runs on real cohort data from delivered affordable housing projects in Denmark, sourced through institutional cooperation with Landsbyggefonden. Under the hood: causal attribution logic, additionality estimation, ex-ante and ex-post analysis, and regulatory export.
This is not another ESG rating. Not a compliance template
A working prototype, already in the room with the people who matter.
In recent weeks, SI4 has been presented to the EU Housing Task Force, DG ECFIN, Landsbyggefonden – the Danish housing fund, Housing Europe, institutional investors and major banking groups. The response has confirmed its relevance for policy evaluation, public-private partnership accountability and the design of blended-finance instruments that mobilise private capital without sacrificing public interest.
It also confirmed the opportunity ahead. Beyond affordability, SI4 can track employment outcomes, health, education, community wellbeing and long-term territorial resilience – a full picture of what housing investment actually does to a place and the people in it.
Next: product enhancement, country-level calibration, AI/ML-enabled modelling, and a federated multi-country benchmark. By 2027, a scalable SaaS platform across geographies and asset types.
The political window is open. The capital is looking for a home. SI4 is building the evidence infrastructure that makes affordable housing investable – without letting it become just another financial product.
PlusValue is looking for design partners, investors, housing data holders and public-sector stakeholders ready to build this with us. If you’d like to explore what SI4 can do for your work, we’re happy to organise a dedicated session.
SI4 launch presentation
Join us online on 22 June 2026, 08:00–09:00 CET for the SI4 launch presentation, in partnership with ICG – Institut für Corporate Governance, Germany’s leading platform for values-oriented corporate culture in the real estate sector. Free to attend.
