Shade provided by street trees during hot summer days improves human thermal comfort. Accurate calculation of the site-specific shade benefit of urban street trees can help designers make planting decisions to maximise shade benefits. However, the current calculation of tree shade benefit does not take into account pedestrian mobility and actual shade experience, which could cause a discrepancy between actual and expected benefits. To address these issues, a theoretical workflow for sitespecific calculation of tree shade benefits is proposed, which includes four steps: data acquisition and processing, tree shade simulation, pedestrian mobility modelling, and spatiotemporal tree shade benefit calculation. We then illustrate this theoretical workflow's required data, digital technologies, and procedures. Two novel indicators called STTSP (Spatiotemporal Tree Shade Provision) and STTSA (Spatiotemporal Tree Shade Availability) are proposed to assess the site-specific tree shade benefit. Finally, we highlight the potential of this novel conceptual approach to support designers in proposing humancentred street tree planting decisions.