External lighting refers to lighting on the outside of the building, namely the façade and site lighting. Outdoor lighting makes us feel safer when night falls, improves visibility, provides a level of security, and generally improves the aesthetic quality of a building at night.

However, the inappropriate or excessive use of outdoor artificial lighting results in light pollution, which is a growing global issue in cities that can negatively affect our environment and impact biodiversity and our quality of life.

External lighting at the HPI d-school Building has been designed and implemented to prevent and reduce light pollution into the night sky by ensuring that there is no point in the sky hemisphere which is exposed to a direct light source emanating from the building.