James McGrath, Miriam Byrne
Bibliographic info:
35th AIVC Conference " Ventilation and airtightness in transforming the building stock to high performance", Poznań, Poland, 24-25 September 2014

Adequate ventilation is necessary to maintain thermal comfort and remove indoor air pollutant concentrations (Crump et al., 2005). Indoor pollutant concentrations vary considerably depending on occupants’ behaviour patterns, building characteristics and meteorological parameters and seasonal effects. Experimental measurements are time consuming and expensive to carry out, while computational models are regarded as a valid complement. The team at NUI, Galway have recently developed the IAPPEM model (described in (McGrath et al., 2014a)representing the state-of-the-art in probabilistic modelling of indoor air quality; the model is currently capable of highlighting locations of different pollutant concentrations within the same building by considering the infiltration of outdoor air pollutants, meteorological parameters and seasonal effects, indoor activities of occupants, emissions from indoor air pollutants, removal by deposition, the dilution of indoor air pollutants through external and internal air exchange and internal house layout.

To date no computational model exists that examines both inter-zonal and external temperatures in combination with assessing indoor air pollutants, and the enhancement of the IAPPEM source code framework to incorporate these features constitutes the main tasks of the current work. This will allow an assessment of individuals’ thermal comfort and exposure to airborne pollutants, and will also allow an assessment of the heat loss to surroundings as a result of changing ventilation rates, a feature that is highly relevant in the context of energy efficient homes. While previous studies have examined the effect of heat loss due to ventilation, no model to date has combined the temperature and airborne pollutant components in a single computational structure.

In this paper, a plan to incorporate a temperature parameter into the existing model is described; this would allow the unique capability to assess, for the first time, the effects of ventilation and occupant behaviour on both an individual’s thermal comfort and airborne pollutant exposure. The basis of the IAPPEM code adaptation strategy will be the addition of a source term and a loss term to account for localised heating sources, such as radiators in each room, solid fuel fires, and cooking events. A loss term will account for the removal of heat through the building walls and windows. Ventilation rates will define the transfer of heat between rooms but also between indoor and outdoor, allowing the assessment of heat loss as well as thermal comfort. This would provide a vital tool in defining optimum building air exchange rates that do not have a negative impact on human health.