The COVID-19 pandemic has shown us how easily indoor spaces can spread diseases like the flu. These illnesses come with hefty price tags—in health, social, and economic terms. To tackle this problem, policymakers need to understand which interventions work and should be prioritised. In order to make evidence-based decisions, we need a comprehensive approach that considers the wider costs and benefits of interventions that will make our buildings and transport systems more resilient against infection in the future.
NERA was commissioned by the Royal Academy of Engineering (RAEng) to develop a social cost benefit analysis (SCBA) tool to evaluate the net impact of interventions to improve infection resilience across building environments in the UK. Our approach (see Figure 1) involved defining a suitable baseline (i.e., what the world would look like without interventions), collecting evidence on the effectiveness and costs of interventions to improve infection resilience, and building a model which incorporates these two aspects to estimate the expected net present value of the interventions. The analysis also incorporates a wide degree of uncertainty to capture the inherent uncertainty of future infection outcomes.
The NERA team included Director Daniel Hanson, Consultants Dr. Francis Ostermeijer and Dr. Tuba Toru Delibasi, and Economic Analyst Khalil Sabourian.
Source: NERA illustration
Notes: Annual lifetime discounted benefits and costs in £ 2020. Lifetime benefits are the sum of annual infection resilient benefits over 60 years. Benefits do not include wider benefits of ventilation such as though improved productivity. Costs include installation, operation, and maintenance. Green indicates a benefit-cost ratio (BCR) of at least 1.5, indicating benefits are at least 1.5 times higher than costs (BCR > 1.5) while red indicates the BCR is below 1.5. Mechanical combined with natural ventilation has similar results as the lower costing scenario. The NPV (net present value) column is for the lowest cost option 3.
This is the first study, to our knowledge, to perform a comprehensive evaluation of health, social, and economic costs of pandemic and seasonal influenza and perform a rigorous social cost benefit analysis of ventilation. The NERA report highlights the following key findings:
When applying these results, it is important to consider that the adopted approach focuses on average effects of improving ventilation in all buildings of a certain type. This masks considerable heterogeneity in impacts and risk factors within aggregate building types. The results do not imply that ventilation should not be installed in any residential buildings (and in all areas for that matter), but rather that a case-by-case approach should be adopted to determine the risk factors (e.g., how densely packed the areas are) and to determine whether ventilation should be improved in these areas.