Ventilation Performance

The Importance of Adequate Ventilation

Maintaining proper ventilation is crucial for healthy buildings, with at least 0.5 air changes per hour recommended to prevent the buildup of indoor pollutants such as cigarette smoke, carbon monoxide, and solvent vapours. Ventilation also helps manage moisture produced by everyday activities like bathing and cooking. Without controlled ventilation, excess moisture can condense within the building, leading to mould growth, dust mites, potential building damage, and decreased energy efficiency.

Mechanical Ventilation with Heat Recovery (MVHR)

MVHR systems address these challenges by continuously circulating fresh air throughout the building while removing moisture and pollutants. Through a high-efficiency heat exchanger, MVHR systems extract heat from the outgoing stale air and transfer it to incoming fresh air. This allows up to 90% of the heat to be recovered, significantly lowering heating costs. As these systems operate 24/7, they maintain indoor air quality while improving the building’s overall energy efficiency.

Alternative Ventilation Systems

• Passive Stack Ventilation (PSV): PSV systems naturally expel warm, moist air through ducts to a roof vent, relying on natural air leakage for fresh air. However, in highly airtight SIP buildings, this method may require permanently open vents, which could result in over-ventilation and energy inefficiency. Additionally, PSV does not incorporate heat recovery, and the incoming air’s temperature and humidity are directly impacted by external conditions.

• Positive Input Ventilation (PIV): PIV systems pressurise the building by introducing fresh air, forcing stale air out through any available openings. For airtight SIP constructions, this may require leaving extract vents open permanently, which could reduce energy efficiency. Some PIV systems address this by pre-heating incoming air using heat from the roof space.

• Extractor Fans: Single-room or multi-room extractor fans help remove moist air from wet areas but do not provide a whole-house solution. These fans expel heat from the building and do not offer heat recovery or filtration, resulting in a decrease in the building’s energy efficiency.

Regulatory Guidelines and Considerations

When constructing with SIPs, it’s important to ensure the ventilation system selected balances indoor air quality with energy efficiency. More detailed guidance on ventilation performance requirements is available in Approved Document F of the Building Regulations, which outlines the Means of Ventilation.

Selecting the right ventilation system for your SIP home is crucial to enhancing both occupant comfort and health while reducing energy consumption and minimising the building’s environmental impact.