Can positive input ventilation tackle surface condensation and mould growth? Literature review and case study of a UK dwelling

Insufficient ventilation is one of the main factors leading to damp and mould in residential buildings. One low-cost method to improve these moisture-related issues is positive input ventilation (PIV) but research data on performance is scarce in the literature. This paper presents a bibliographical review together with a case study based on monitoring a residential building by means of environmental sensors. The review reveals the importance of correct location, installation, operation and continued maintenance of mechanical ventilation systems. Specifically, PIV and exhaust ventilation units in existing buildings require routine checking to ensure these systems are working correctly and efficiently. The results of monitoring ambient and surface temperature and relative humidity show that the PIV and enhancement extract fan set-up can reduce atmospheric moisture levels and avoid surface condensation. Mould growth is no longer active, but it is always essential to perform thoughtful building inspections checking the right conditions for installation and maintenance to ensure the proper functioning of the units. It is critical to study the size of the building and structural characteristics of the roof and ceilings. Also to verify that the doors are well undercut to allow air flow and that the occupancy levels and regional climate are adequate for selecting the appropriate type of mechanical ventilation units and corresponding operational modes (flow rates, operational settings, etc.). More research, measurements and monitoring studies pre- and post-installation of PIV and other whole house mechanical ventilation systems are recommended to assess optimal performances. This could also help to ensure the success of retrofitting projects in residential buildings which aim to improve energy efficiency but also make buildings relatively airtight and prone to condensation damp. An effective, sufficient and appropriate ventilation system as well as a good installation practice and adequate maintenance is key to avoid surface condensation and mould growth and to improve the indoor air quality of both new and existing buildings.