Adequate ventilation performance is critical to a healthy living environment. Correct ventilation can have a positive impact on well-being, occupant comfort and building ambience. Healthy buildings usually require a minimum of 0.5 air changes per hour (m³/m²hr). The air-tightness of a correctly installed SIP system is far superior to traditionally constructed buildings, so developers should pay serious attention to ventilation methods.
Healthy Living Spaces
Insulated structural joints and connections combined with exacting panel tolerances allow SIPs to achieve low levels of air leakage – as low as 0.6 m³/m²hr@ 50 pascals air pressure as standard. Adequate ventilation is integral to building performance.
Water vapour, built up through activities such as bathing and cooking, condenses on the fabric of the building, creating an environment where mould and dust mites can flourish. Indoor air may contain pollutants such as cigarette smoke, carbon monoxide and solvent vapours, while external air pollutants may also be present (traffic fumes, pollen, noise). Inadequate ventilation performance can lead to building damage and a lack of energy efficiency. The solution is a controlled ventilation system.
Mechanical ventilation with heat recovery (MVHR) offers 24-hour continuous ventilation for a SIP house. An MVHR circulates fresh air, removing unwanted moisture and pollutants. The air passes through a high-efficiency heat exchanger, extracting the heat from stale air and transferring it to incoming fresh air. MVHR systems, in combination with the SIP insulating properties, can improve energy efficiency, recovering up to 90% of heat in outgoing air.
Passive stack ventilation (PSV) system channels warm, moist air through ducts to a fan-less outlet vent in the roof. Due to SIPs superior air-tightness, these inlet vents often must remain permanently open, risking over-ventilation and compromising energy efficiency. Since heat recovery is not an option, incoming air will be the same temperature and humidity as outside. The PSV system may also create negative pressure inside the structure – and may prevent fireplaces and stoves from venting.
Positive Input Ventilation (PIV) systems use a fan to blow fresh air into the house, pressurizing the building and forcing moist air through cracks, doors and windows. In very airtight buildings, additional extract vents may be required. As with PSV, these vents often must remain permanently open. Some systems can gather some heat from the roof space to temper incoming air, reducing running costs.
Single-room or multi-room extractor fans blow moist air out of wet rooms, allowing heat to escape and lack the power and ability to ventilate, recover heat or filter the incoming air, reducing energy efficiency.