Multi-objective optimization of ceiling-to-floor systems in timber buildings taking into account structural and HVAC related objectives

The design of compact ceiling-to-floor systems (CTFS) in timber buildings can be challenging involving different disciplines in a sequential approach, each facing potentially conflicting objectives and constraints. In particular, the CTFS contains structural components such as beams and floors, and is also used for the passage of mechanical, electrical and plumbing (MEP) elements providing various services to occupied zones. An integrated design of CTFS in which different disciplines are considered simultaneously could improve its overall performance. In this paper, we present a multi-objective optimization strategy aiming to design and optimize ceiling to-floor space in timber buildings. By focusing on both structural and ventilation systems, the framework involves the minimization of the assembly thickness and the pressure drop in the air distribution ductwork. The NSGA-II algorithm is used to solve the optimization problem. Three possible configurations of beam-duct interactions are considered: (i) the diameter of an aperture in a beam to let a duct pass is limited to 15% of the beam height, (ii) the aperture diameter limitation is 30% of the beam height, corresponding to a beam with reinforcement, (iii) no apertures are allowed, and the ducts are below the beams. For the case study, results show that the optimization algorithm gives better results in terms of thickness and pressure drop in the third configuration, compared to the configuration where ducts pass through structure.