New Builds and Extensions
A ventilation provisions must be demonstrated in any of the following ways:
a. Incorporating background ventilators (trickle vents) in the windows, equivalent to the following minimum equivalent area (EQA) (for dwellings with multiple floors):
i. Habitable rooms – 8000 mm2 EQA.
ii. Kitchen – 8000 mm2 EQA.
iii. Bathroom (with or without a toilet) – 4000 mm2 EQA.
b. If the dwelling will have continuous mechanical extract ventilation without heat recovery, windows in habitable rooms which are not wet rooms must have a minimum background ventilation area of 4000 mm2.
c. Other ventilation provisions, if it can be demonstrated to a building control body that they comply.
Replacing Existing Windows
Existing windows with background ventilators (trickle vents)
If existing windows have background ventilators, the replacement windows should include background ventilators. The new background ventilators should comply with both of the following conditions:
a. Not be smaller than the background ventilators in the original window.
b. Be controllable either automatically or by the occupant.
Existing windows without background ventilators (trickle vents)
Replacing the windows is likely to increase the air-tightness of the dwelling. If ventilation is not provided via a mechanical ventilation with heat recovery system, then increasing the air-tightness of the building may reduce beneficial ventilation in the building. In these circumstances, it is necessary to ensure that the ventilation provision in the dwelling is no worse than it was before the work was carried out. This may be demonstrated in any of the following ways:
a. Incorporating background ventilators in the replacement windows, equivalent to the following minimum equivalent area (EQA) (for dwellings with multiple floors):
i. Habitable rooms – 8000 mm2 EQA.
ii. Kitchen – 8000 mm2 EQA.
iii. Bathroom (with or without a toilet) – 4000 mm2 EQA
b. If the dwelling will have continuous mechanical extract ventilation without heat recovery, replacement windows in habitable rooms which are not wet rooms must have a minimum background ventilation area of 4000 mm2.
c. Other ventilation provisions, if it can be demonstrated to a building control body that they comply.
Please note:
- Background ventilators are intended to be normally left open.
- If the dwelling is close to an area of sustained load noise (e.g. a main road), then a noise attenuating background ventilator should be used.
- Window night latches are not acceptable as a mean of background ventilation.