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Technical questions - small power, steam rooms and CDMApril 2008

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

Computers and small power loads

What small power load savings can be made on office computers?

Unplugging a computer when it's not in use is an easy way to reduce carbon dioxide emissions. A quick test on the BSRIA computers revealed that desktop computers are consuming 15 W after they are shut down. Laptop adaptors were also draining 5 W after being switched off, so should also be unplugged when not in use.

Switching to a liquid crystal display (LCD) flat screen from a cathode ray tube (CRT) can lead to significant savings. Our quick check on consumption for viewing a Google page was 23 W for the LCD screen as against 64 W for the CRT.

If CRT monitors are retained (perhaps to save embodied energy in new equipment) then an energy saving of about 18 percent can be made by switching to the Blackle form of Google (52.65 W compared with 64.11 W for the usual form of Google).

Ventilating a steam room

How should I ventilate a steam room?

A steam room is a cabin with internal seating into which steam is introduced from an external generator, to provide a wet air temperature between 45 and 50 degrees C. The Swimming Pool and Allied Trades Association issue standards for steam rooms. It advises that a 100 mm rigid-plastic vent should be connected to the steam room.

A pipe should be connected to the rear of the roof and run directly to outside air, within a distance of eight metres. The vent pipe is connected to an adjustable air vent within the cabin. If the run exceeds eight metres an in-line ventilation fan should be installed.

CDM responsibilities explained

What are the specific duties of a CDM co-ordinator?

The latest (2007) edition of the Construction (Design and Management) Regulations introduced the new role of CDM co-ordinator.

A competent and adequately resourced CDM co-ordinator must be appointed on a notifiable project (those lasting more than 30 working days, or involving more than 500 person days). The co-ordinator is required to identify and extract all information required to secure the health and safety of anyone engaged in construction work.

The CDM co-ordinator may be an individual or a company, and is appointed by the client, whose responsibility it is to assess the CDM co-ordinator's competence.

The CDM co-ordinator must ensure that projects comply with the Regulations. The main duties include:

  • written notification to the Health and Safety Executive of a notifiable project 
  • to provide sufficient advice to the client 
  • to maintain cooperation among everyone involved in the project to maintain and implement health and safety measures 
  • to identify pre-construction information and ensure every person is supplied with this information 
  • to liaise with the principal contractor regarding ongoing design 
  • to maintain, review and update the health and safety file and liaise with contractors.

Further details are in Managing Health and Safety in Construction. Construction (Design and Management) Regulations 2007. Approved Code of Practice. L144, HSE Books 2007.

Fire risk assessments

In multi-occupancy buildings, who should conduct the fire risk assessment?

Premises with five or more employees must conduct and record a fire risk assessment.

The landlord, owner and/or managing agent of multi-occupancy buildings is responsible for the areas which affect the life-safety and for the property protection systems. These systems include fire alarms, detection systems, emergency lighting, fire extinguishers, sprinklers, risers, fire dampers, staircase pressurisation, signage, means of escape, and maintaining service records.

In a multi-occupancy property, the occupier of any leased space who employs more than five people will be responsible for carrying out a fire risk assessment. This will include hazards/mitigation in the space, portable fire equipment, training, maintaining any special fire safety systems, means of escape, and development of emergency procedures.

Heat sources beneath windows

What is the best heat source beneath a large window?

The issue of whether it is possible to do without radiators or trench heating beneath windows is related, among other things, to cold-air drop or down-draughts.

If the radiator beneath the window is omitted or is installed in only every second bay, the down-draught will possibly reach the floor, even where the windows are only 2-3 metres high. This will then cause cold-air currents in the room that will adversely affect comfort. The effect will usually be perceived in the form of cold feet and draughts around the legs.

Published test results have shown that the window frame, and not the window pane alone, is the critical element. The authors contend that buildings with window sills and highly insulated windows (glazing and frame) need no heating appliances under the window or other means to compensate cold air down-draughts. Exceptions can be situations with glazing heights greater than two metres, a very cold climate or special requirements. Also see Energy and Buildings 2001, Vol 33, No 5, pages 489-493.

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