Projects in the indoor air quality stream
BRANZIAQ
BRANZIAQ - indoor air quality model - was an aspirational technical goal for the programme. We combined computer models from the other streams (where IAQ is also a theme) to form a more complete model.
It started life in a previous program, where we proved the concept of coupling computational fluid dynamics software with energy simulation software. By combining the two, we could get a more realistic simulation of what is happening in the indoor environment of a building - adequate detail for the flow field within the room that reflects the change in boundary conditions.
The aim was to:
- look at the interaction with the actual structure - the effect of having wet walls
- analyse the effect of putting in an IAQ device such as a photocatalytic oxidiser chamber
- incorporate the effect of ventilation systems in terms of moisture removal.
Photocatalytic oxidisers
The stand-alone performance (rating) of photocatalytic oxidisers (PCOs) was characterised in an environmental chamber manufactured by AgResearch to look at rates of:
- breakdown of volatile organic compounds (VOCs) including formaldehyde
- denaturing of allergens
- lethality to mould spores, bacteria and viruses.
Pollutants at a known concentration were introduced into the chamber containing the PCO and the concentration of the pollutant measured in the exhaust stream of air, allowing calculation of the pollutant removal rate. In situ performance, including in classrooms, was then compared to predictions from BRANZIAQ. The computational fluid dynamics capacity of BRANZIAQ was vital to explore how air currents in the room affect optimum placements for these devices. This new understanding was used to develop tools to calculate sizing, placement and so on required to meet design goals.