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Guidance for gasesSeptember 2007

BSRIA's Librarian Stephen Loyd shares the answers to the more frequent technical enquiries from BSRIA Members.

Replacing R22 refrigerant

How soon should I replace the R22 in my refrigeration equipment?

The simple answer is to start planning immediately. R22 damages the ozone layer, and under the current phase-out timetable there is a ban on the use of virgin R22 (and other HCFCs) for servicing and maintenance from January 2010. After this date only recycled HCFCs will be permitted.

This will be followed by a complete ban on the use of R22, including any that has been recycled, from January 2015.

However, even this final date could be brought forward to 2012 if signals emanating from Brussels are to be believed.

A sensible option would be to start trialling alternatives on less critical applications straight away - any change will require investment either in converting equipment or in replacement.

Ventilating gas meter houses

How should I ventilate a gas meter housing?

The purpose of ventilation in meter houses is to ensure that minor gas leakage does not cause the atmosphere within the housing to become unsafe, and also to minimise condensation.

The requirements are presented in a publication by the Institution of Gas Engineers GM/1 Gas Meter Installations for Pressures Not Exceeding 100 bar.

Natural ventilation is required, with non-adjustable ventilators to the outside at both high and low levels. The total effective ventilation area should not be less than 2% of the floor area of the enclosure.

The low-level openings should be positioned approximately 150 mm above the floor. The high level opening should be as close as possible beneath, but not more than 10 percent of the total height below the roof or ceiling level.

Ventilation for bin rooms

Where can I find the ventilation requirement for a bin room?

Ventilation of bin rooms in blocks of flats should vent any odorous or dense flammable gases that may escape from the waste.

The requirement is given in Approved Document B Fire Safety, volume 2 of the Building Regulations. This states that bin rooms should be accessible from the exterior of a building, or by way of a protected lobby provided with not less than 0.2 m2 of permanent ventilation.

The room's passive ventilators should be fly and vermin proof and located as near the ceiling and the floor of the room as possible, but away from windows of the flats. The ventilators should not be in the form of louvred doors, and may need to be fire resistant.

Further information can be found in BS 5906, Waste Management in Buildings - Code of Practice.

Water risk assessments

What water risk assessments are needed for unoccupied buildings?

Even if a building is unoccupied, someone will still be deemed responsible for the building. Surveyors or maintenance staff may still need access.

If a water system remains inactive for longer than a month, harmful bacteria can start to proliferate within the stagnant water. In general health and safety terms, it will be necessary to carry out risk assessments.

When a building is unoccupied, the legionellosis risk assessment is different from that required for an occupied building. There is likely to be a lower water turnover (which will increase risk) but a lower exposure (which will decrease the risk).

Cold water will tend to warm up and the hot water cool down to room temperature, increasing risk. However, with little heating, lighting and plant operating, the room temperatures (especially in plantrooms) will be lower. This will decrease risk.

Routine inspection may be reduced (decreasing the frequency of exposure) but any works carried out would involve contact with water which has become stale or stagnant (increasing the intensity of exposure).

The HVCA has recently issued good practice guide Mothballing and re-commissioning of buildings. This guide is available on loan to Members from BSRIA's library service.

Definitions of building classes

Where can I find the schedule of building classes?

This question is a good example of data in common use, even though its origin is generally unknown.

From a planning perspective, buildings are classified according to their purpose. There are four distinct classes with subdivisions presented in the Town and Country Planning (Use Classes) Order 1987.

In brief, the classes are:

  • Class A A1: shops, A2: financial and professional services, A3: food and drink.
  • Class B B1: Business, a) offices, b) research and development, c) other industrial processes appropriate in a residential area.
  • B8: storage and distribution centers
  • Class C C1: hotels, C2: residential institutions, C3: dwelling houses
  • Class D D1: non-residential institutions, D2: assembly and leisure.

The full detailed classification may be viewed on the Office of Public Sector Information web site.

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