Depending on building type users are likely to be using TM52 or BB101 standards to meet UK & Eire compliance requirements. Both standards can be accessed via the VistaPro > Comfort analysis dialog.
Taking BB101:2018 as the example; set the user category, the build type, and the system type. For Passivent Roof Terminals the system type should be set as follows:
· Airscoop ® – natural ventilation system
· Airscoop® with mixed mode cooling – hybrid ventilation system
· Airstract® – natural ventilation system
· Airstract iAT® – natural ventilation system1
· Hybrid Plus Airstract - natural ventilation system2
· Litevent – natural ventilation system
1 Airstract iAT® is free running for the majority of the time and the fan within it is not there to deal with CO2 but only there to deal with overheating and to boost ventilation if required on a hot day as it is also supplemented with low level openings be that a window or an Aircool® device. In winter-time when CO2 levels are being targeted (rather than internal temperatures) the boost fan wouldn’t be expected to come on so ‘mechanical mode’ is not applicable.
2 Hybrid Airstract® has been argued to be a natural ventilation system as during winter-time if you switch the fan off you will still get a natural exchange of air from the room to the outside. The purpose of the fan in this unit is just to prevent a cold draught from occurring so wouldn’t be considered as a mechanical ventilation system as it’s predominately used for occupant comfort against cold draughts rather than being required to deal with CO2.
Now press the Create report option. The VE will carry out the analysis with these settings and export a report in Excel format.
For Airscoop with mixed mode cooling the analysis will assess periods when cooling is operating separately to free running periods.
For Roof terminals with fans the analysis will assess periods when fans are operating separately to free running & mechanical cooling periods.
