This programme is the first in the NBS Learning Channels series on the Code for Sustainable Homes. It introduces the Code and its standards for the environmental performance of dwellings. It explains the nine categories for which sustainability is assessed, the Level (or star) rating system, and the recommended compliance, assessment and certification processes. It explains the credit system used to assess sustainability, the mandatory nature of some categories and shows how each category is “weighted” to convert credits into a Level (star) rating for homes.