Ventilation's role in adaptable school buildings: Comparing traditional and adaptable strategies through life cycle assessment

Adaptable buildings are a promising enabler in the transition towards a more circular economy, with the ambition of using materials as efficiently as possible. To exploit adaptable buildings to their full potential, HVAC designers should critically rethink how to design technical services and ventilation systems in particular. This case study illustrates how five ventilation strategies perform from an environmental point of view in a school building where the configuration of the floorplan changes every five years, each of the changes reflecting a pedagogical vision. Consequential LCA is used to assess the environmental impact. A decentralized balanced mechanical ventilation system, which requires almost no adaptations when the configuration changes, has the lowest environmental impact while mechanical exhaust ventilation has the highest. However, when the configuration of the floorplan layout alters more rapidly, the relative environmental impact of the latter decreases substantially. The main conclusion is that, in a flexible context, the material-related environmental impact gains importance over the energy-related impact. With respect to this conclusion, a key finding is that minimizing the material use of ductwork (rather than oversizing ductwork dimensions to decrease the energy consumption of the fan) is more sustainable from an environmental point of view. Finally, distributing the ductwork over two shafts offers more flexibility and results in a lower environmental impact as this allows for the use of smaller dimensions of ductwork.