Algorithmic planning of ventilation systems: Optimising for life-cycle costs and acoustic comfort

The European Union’s climate targets challenge the building sector to reduce energy use while ensuring comfort. Ventilation systems play an important role in achieving these goals. During system planning, the primary focus tends to lie on reducing life-cycle costs, including energy and investment expenses. Acoustic considerations which contribute significantly to occupant comfort, are either addressed as an afterthought or overlooked. This can result in suboptimal designs, where silencers are added indiscriminately without properly assessing their necessity. This paper introduces a novel method for optimising life-cycle costs through mathematical optimisation while adhering to predefined noise limits. We propose new model equations with reduce non-linearity better suited for integration into the optimisation framework. Further, they present a comprehensive approach to optimising ventilation systems under multiple load scenarios. Our method surpasses the traditional sequential approach by enabling simultaneous consideration of airflow and acoustics in a single, holistic optimisation step. A case study demonstrates the method’s practical application, showing that optimal solutions can be computed efficiently. The results reveal that, with appropriate fan selection, many silencers can be eliminated. Additionally, the method supports decision-making by transparently illustrating the trade-offs between life-cycle costs and noise limits. Notably, while optimal solutions from the sequential and holistic approaches align for most noise limits, the holistic method achieves a 12% reduction in costs under specific noise constraints. These results demonstrate the benefits of integrating airflow and acoustic design while underscoring the need for further application on more diverse building types and more complex ventilation system configurations. • Mastering the complexity of acoustic phenomena in ventilation system design. • Coupling airflow and acoustics in a Mixed-Integer Nonlinear Program. • Deriving new model equations for fans, volume flow controllers and silencers. • Trade-off between life-cycle costs and noise limits enables transparent decisions. • Holistic optimisation allows life-cycle costs to be reduced by up to 12%.