Neighbourhood health starts with air and movement. Mechanical ventilation (€1,700–€2,100 per home, most valuable in the 80% of homes built before 2000) purifies indoor air and returns €3.27 per euro invested; two sports and play areas at €10,000 each deliver €2.08 per euro.
Together per model neighbourhood: around €210,000 in societal value against €72,000 in costs. Healthier residents mean lower healthcare costs and less absence, while green-designed play and sports areas also cool the street, let water infiltrate and support biodiversity. Source: Transform Zuid-Holland.