Ventilation of Living Spaces

General requirements

The requirements for ventilation of a Recreational Vehicle with a gas installation are found in AS/NZS 5601.2:2020 Section 7

In any RV with gas appliances installed, consideration must be given to adequately ventilating the living spaces to prevent the build-up of condensation, products of combustion or other toxic conditions.  Wherever appliances (including room-sealed ones) are installed within a living space, ventilation must be provided.

Note: these ventilation requirements are in addition to vehicle standards requirements for openable windows – refer ADR 42.

Size of openings

Where an appliance is installed in a way that any part of the appliance is inside the RV (or an annex/tent) the total area of ventilation provided must be the greater value of

1. 4000mm²; or
2. The area obtained from the following formula:
   Area = (610 x U) + (650 x P)
   • U is the sum of the appliance ratings in MJ/h for all gas appliances other than room-sealed ones.
   • P is the number of sleeping berths in the recreational vehicle

So, any space which has a gas appliance installed (including room-sealed appliances) must have vent openings with a total area that is at least 4000mm² or the value obtained from the formula – whichever is larger.

Example 1:

A small hybrid caravan is fitted with a bar fridge and small hot water service, both of which are room-sealed installations.  This RV will be required to have a total open vent area of at least 4000mm² area.
This could be achieved with 2 square/rectangular vents of at least 45mm x 45mm dimensions.

Example 2:

A caravan is fitted with several room-sealed appliances (eg fridge, hot water unit) and an indoor gas cooker. The gas cooker is rated at 29MJ/h (8KW) and the RV has 2 sleeping berths.

The calculation for ventilation area will be as follows:

Area = (610 x 29) + (650 X 2) = 18,990 mm²

Since the calculated area is the larger figure, the required of ventilation openings for this RV must be at least 18990 mm².  This could be achieved with 2 square/rectangular vents of 100mm x 100mm dimensions

The calculated ventilation area is to be understood as strictly a minimum requirement for safety, and exceeding the minimum calculated area where possible is recommended. 
Note that these vent openings do not replace or reduced the amount of ventilation (by way of openable windows) that is required by road vehicle regulations.

Appliances outside the living space

For the purposes of vent size calculations, appliances the following situations are not considered to be within the RV:

1. An appliance that is located in a compartment or locker that is outside the RV floorplan.  For example, an appliance located in a storage compartment on the A-frame of a caravan.
   Refer AS/NZS 5601.2 Figure 7.3.1
2. A stowed appliance that is installed with the correct gas shut-off features.
   (In line with the requirements of clause 6.3.2.  More information on these requirements can be found here: Slide-out Cooker installation)

Allowance for louvres and mesh

Louvres or mesh installed across the ventilation openings restrict the free area for air flow through the opening.  In this situation, an increased opening area is required to compensate.  As a guide, the area of the ventilation openings should be doubled to ensure sufficient free flow area is achieved.

Looking back to Example 1 above:  if these 2 vents had fly mesh over the opening, an increase to a total area of at least 8000mm² would be necessary.  This would increase the vent sizes to at least 65mm x 65mm each.

Position of openings

In order to allow a flow of air through the living space, ventilation openings must be located at a high-level and low-level position and must open direct to the outside.  Don’t forget that an enclosed annex/tent space is not “outside” for this purpose – ensure that ventilation openings are outside any area that is enclosed, or has provision to become enclosed.

There must be at least 2 openings that are fitted at opposite ends or sides of the living space.  If the living space can be divided (eg by a door) the openings must be in the same compartment as the gas equipment.

The high-level vent must be located no more than 150mm from the highest part of the ceiling.  The low-level vent must be fitted as low as possible and no more than 150mm from the floor of the living space. 
The size of each of these vents must be at least half of the total required ventilation area.

High-level ventilation openings can be in the form of a roof hatch if the following 2 requirements are both met:

1. There is fixed (permanently open) ventilation when the roof hatch is closed.
2.  The hatch is located at the opposite end of the living space to the lower vent.

If a roof hatch is used as the upper ventilation opening, it is important to obtain written confirmation from the component supplier confirming the following:

1. The ventilation status – that there is open ventilation in the roof hatch in all functional positions.
2. The free area (in mm²) of the openings when the roof hatch is in the closed position.

RV product types

Pop top style products must have ventilation that is effective at all times – when the top is raised or stowed.

Camper-trailer products that are fully collapsible can have ventilation that is only effective when the structure is erected.

Motorised product (motorhomes and campervans) must not have ventilation openings located in the rear wall of the vehicle.

Warning labels

Each vent opening must have a permanent, legible warning label advising the user to ensure the vent remains open and clean.  The wording and font size of the label are specified (refer clause 7.7)

A suitable label is available from the RV Merchandise Catalogue (item C-5D).

More details on mandatory gas warning labels (including the ventilation warning labels) can be found here:  Gas laws, labels and you!

Lower vent opening covers

Amendment 2 of AS/NZS 5601.2, published in September 2024, introduces requirements for a lower vent that is covered during travel for such purposes as avoiding the ingress of water or dust.

If a lower vent is to be covered in this way, both of the following requirements must be observed:

1. The design of the vent opening cover must ensure that the cover is removed before gas appliances can be used.
   Some examples:
   • A cover that must be completely opened to allow access to a vehicle with internal gas appliances.
   • A cover that includes a gas interlock device to prevent the flow of gas to appliances when the cover is in place.
2. A carbon monoxide detector must be installed.
   This detector must meet the requirements of EN 50291-2 or UL 2034 standards, which include the detection of low concentrations of carbon monoxide and the presence of an audible alarm.