• mechanical ventialtion
• low energy buildings
• CFD

Adequate ventilation in buildings is an essential requirement to ensure the health and comfort of the occupants. The European Energy Performance of Buildings Directive (EPBD) and UK Building Regulations are becoming increasingly stringent in relation to reducing energy demand, necessitating airtight building envelopes, and mechanical ventilation systems. Mechanical ventilation systems with heat recovery (MVHR), are commonly specified as an effective means to achieve stringent energy efficiency and ventilation performance standards. This work investigates the optimal design and positioning of MVHR intake and exhaust ductwork terminals for low energy dwellings. The research focuses on minimising cross contamination risks arising from poor positioning, design, and separation between the air inlet and the air exhaust terminals. The aim of the research is to inform the optimal design and positioning of the system terminals and highlight any risk factors. Empirical evidence drawn from the monitoring of domestic MVHR systems in relation to cross contamination of heat and CO2 was evaluated under random wind speed, direction and temperature cycles. Computational Fluid Dynamic (CFD) models were created and validated against the empirical data in order to study the problem numerically. Using Sensitivity Analysis (SA) techniques these models were then used to inform the guidelines for design optimisation.