SAP calculations meticulously evaluate the energy efficiency of dwellings, with a focus on various types of mechanical ventilation systems, including centralised and decentralised systems. Centralised Mechanical Ventilation and Heat Recovery (MVHR) systems are assessed based on their thermal performance and installation location, while Specific Fan Power (SFP) test measurements are adjusted to better reflect real-world installations. Decentralised Mechanical Extract Ventilation (dMEV) systems are evaluated for aerodynamic performance, with improved test data in recent SAP updates ensuring accurate assessments. Efficiency and integration with other building components, such as insulation and renewable technologies, are critical factors, helping to reduce energy consumption and improve overall building performance.

The interplay between airtightness and fire safety in buildings is complex, necessitating a delicate balance between energy efficiency and safety measures. While airtight designs contribute to reduced energy consumption, they can inadvertently hinder smoke control systems, such as pressure differential systems, by limiting air leakage paths crucial for preventing smoke infiltration into escape routes. Additionally, the increased heat retention in airtight buildings can intensify fires, complicating smoke movement and control, particularly in tall structures affected by stack effect and wind forces. Ensuring that air barriers and fire stopping materials are correctly installed and maintained is vital, as is adapting smoke control system designs to reflect the tighter air permeability standards of contemporary buildings.