How Does Brick Compare to X? # Project Haystack is a popular tagging system for describing building assets using semi-structured sets of tags. Because there are no formal rules for how tags can be used, Haystack-based descriptions of buildings tend to consist of ad-hoc collections of tags, resulting in highly custom and inconsistent modeling practices across sites. Brick includes a tagging system similar to Haystack that augments tags with formal semantic rules that promote consistency and interpretability.