Digital twin technology is often overlooked in early architectural design stages, with most studies focusing on final applications and performance evaluation. Our research bridges this gap by exploring hybrid prototypes, combining digital and physical models enriched with sensors by a "foetal" digital twin during conceptual design, representing the eventual "adult" version. Physical twins collect data, while digital twins simulate and optimize within these prototypes. We utilize a foetal physical twin collecting and transmitting data for a more sustainable architectural design process.