Modern high-performance composite materials, such as carbon textile-reinforced concrete, offer a new potential for developing structural systems that promise a significantly higher sustainability compared to state-of-the-art. However, this promise can only be fulfilled if both material components are fully utilized. Indeed, without proper selection of design parameters, a significant portion of the high-performance material remains wasted, raising concerns about the environmental impact particularly related to the carbon reinforcement material with considerable high specific CO₂ footprint. Therefore, it is crucial to evaluate the environmental impact in direct relation to the functional performance of structural elements. Our contribution sketches the chain of mathematically formulated criteria that enables us to link the functional performance, defined by serviceability and ultimate limit states, with the material efficiency of the design. In simple terms, we enhance the recently published closed-form model identifying the design parameters of fully utilized cross-sections with the direct evaluation of the equivalent carbon footprint related to the functional unit represented by one square meter of a floor area. Our goal is to stimulate further refinements of the performance-based sustainability metrics that can be directly embedded in the numerical design models and assessment rules for emerging construction materials.