Remediating moisture- and mould-damaged residential buildings in Finland – Costs and benefits for health and climate

Mould and moisture damage in residential buildings increase the risk of new-onset asthma and of respiratory symptoms. Alternatives for remediating the damage in external wall structures vary in co-benefits for climate and economy. Integrated assessment of the costs, and health and environmental benefits, of different remediation alternatives is needed for sustainable decisions. We compared two commonly used remediation alternatives of damage in external wall structures in the whole Finnish residential building stock: an immediate replacement of the damaged materials (material replacement, MR) with up-to-date energy-efficient materials and a delayed MR (DMR) preceded by improvement of airtightness. MR yielded a somewhat better discounted net cost benefit (−€5.9 bn) than DMR (−€6.4 bn) over service-life (50 and 60 years, respectively). Benefits for health (€1.2 bn and €1.2 bn for MR and DMR, respectively) and savings in heating (€0.6 bn and €0.5 bn, respectively) could not offset the remediation costs (−€7.7 bn and −€8.0 bn, respectively). The service-life climate impact of both alternatives was negligible. In the sensitivity analysis, variation ( ± 20 %) in remediation costs had the most significant impact on net cost benefit (−€2.7 bn to −€7.3 bn). The assessment did not include all effects of remediations, like future value of the building, which could have a major effect on the estimated net cost benefit. However, the present study presents, to our knowledge for the first time, an integrated approach that can help in identifying sustainable remediation alternatives when societies adapt to and mitigate climate change.