The Healthy and Efficient Retrofitted Buildings Tool (HERB), developed by C40, helps cities and communities evaluate the potential benefits of building retrofits, including health, socio-economic, and climate impacts. 

The tool uses an Excel template with a technical manual to calculate benefits based on project data and can be applied to single buildings, groups of buildings, or larger urban areas. Open-access and user-friendly, HERB supports planning and decision-making, but its focus on area-scale assessments, reliance on regularly updated multipliers, and limited scope to benefit calculations may restrict its use for detailed building-level interventions.