Understanding Ventilation in Occupied Case Study Dwellings with System 1 Ventilation Strategy (Trickle Vents and Mechanical Extract Fans)
Jessica Few, UCL Energy Institute
The ventilation rate influences the indoor air quality and the energy use of a building. The most common ventilation system for newly built dwellings in the UK is natural ventilation with trickle vents and mechanical extract fans (referred to as system 1), but the ventilation rates achieved with this system in occupied dwellings has yet to be studied in detail. This study will address this research gap and will involve measuring ventilation rates in several case study dwellings, investigating the physical form of these buildings and interviewing the occupants about their use of the ventilation system to understand the whole system.
Ventilation in dwellings is influenced by factors including spatial configurations, weather conditions and occupant behaviour. For this study the ventilation rate will be measured using the tracer gas concentration decay technique with metabolically generated CO2 over several seasons. This will facilitate an understanding of how ventilation rates are manifested in occupied dwellings, and how this ventilation rate varies, both in time and in different locations in the dwellings. This will give an understanding of whether the current UK building regulations are providing the expected ventilation rates in dwellings.
The research also aims to understand how and why occupants engage with their trickle vents as part of their ventilation behaviour. The trickle vents are of particular interest because their sole use is to provide ventilation and they have been designed into newly built dwellings specifically to provide adequate ventilation in response to increased airtightness. The stated intention in ADF is that they are left open all the time, but previous examples in the literature have often found them closed.
Overall, this research will provide understanding on the issues around ventilation in dwellings with trickle vents and mechanical extract fans. This ventilation strategy is extremely common, and as dwellings become more airtight it is crucial that we understand how they are performing in terms of ventilation and why, so that any unintended outcomes of using this strategy can be addressed.