Approved Document O¶
Approved Document O uses the CIBSE TM59 methodology as a basis for assessing overheating risk for domestic properties. For full details, see Approved Document O
For Part O, the occupant control of apertures depends on the time of day.
Approved Document O specifies that, during the day (8am to 11pm), openings should be modelled to:
Start to open when the internal temperature exceeds 22°C
Be fully open at 26°C
The apertures should close using the same profile when the temperature falls.
In Tas, this can be achieved in the Building Simulator using the ZDWNN function:
This function should be used if the apertures stay closed during the night.
Approved Document O specifies that, during the night (11pm to 8am), the openings should be modelled to be fully open if:
The opening is not on the ground floor and is not easily accessible
The internal temperature exceeds 23°C at 11pm
This can be achieved in Tas using the Building Simulator and the ZDWNO function:
This function behaves like zdwnn during the day, but if the dry bulb temperature of the zone at 11pm exceeds 23°C, the aperture will remain open until 8am.
This function should not be used with schedules.
ZDWNO is an aperture function introduced in Tas v9.5.4