Building standards - ministerial view: escape (ref. V2022/2)

Functional Standard 2.9 Escape

Standard 2.9 (Escape) states: ‘Every building must be designed and constructed in such a way that in the event of an outbreak of fire within the building, the occupants, once alerted to the outbreak of the fire, are provided with the opportunity to escape from the building, before being affected by fire or smoke.’

2.9.21 Electric locking devices that unlock on electrical power being withdrawn

Where there is a choice of escape routes and the doors on one direction of escape are fitted with devices giving mechanical escape which operate on body pressure alone to BS EN 1125: 2008 or by the use of a lever handle or push pad to BS EN 179: 2008, the alternative escape route could be fitted with fail unlocked, electric locking device, such as an electro-magnetic lock. These are devices that require electrical power to be withdrawn from them to unlock.

Verifier 

Aberdeen City Council

Technical context 

The building warrant application is for alterations to an existing office building, circa 130 years old, and the referral relates to Mandatory Standard 2.9. Specifically, to guidance clause 2.9.21 in respect of electro-magnetic locks (mag-locks). The guidance states that mag-locks may be used where there is a choice of escape routes and the doors on one direction of escape are fitted with devices giving mechanical escape which operate on body pressure alone (non mag-locked)

The view of Scottish Ministers

On behalf of Scottish Ministers, the Building Standards Division has considered all the information submitted in this case and their view is set out below.

The key area of doubt is in relation to compliance with standard 2.9 and whether the access control system to the offices is appropriate given that there is no alternative exit. The proposal indicates that the electronic locking devices will release the door by push button and are installed to meet all aspects described within clause 2.9.21. Therefore, the focus of this Ministerial View is on whether the proposal adversely affects occupants opportunity to escape should they wish to evacuate.

BS 7273-4:2015 Code of practice for the operation of fire protection measures – Part 4: Actuation of release mechanisms for doors states, “in principle, actuation of release mechanisms is intended to occur in response to any of the following conditions: 

• operation of the fire detection and alarm system, whether by operation of a manual call point or activation of an automatic fire detector
• any failure of the fire detection and alarm system including system error
• any electrical power failure and 
• in the case of electronically locked doors, activation of a manual release control”

Concerns regarding residual magnetism within these devices, thus potentially holding a door closed despite activation of the alarm or local break glass switch have been previously expressed. The applicant has however indicated that “the devices are fitted with double pole switches which will instantly drop the supply and coupled with the ‘anti-residual magnetism protection’ on the magnet, will allow instant egress.” 

The verifier agrees with the applicants view indicating “double pole switches provide extra assurance that the active system of release will operate directly and without failure. With this in mind, there is doubt whether the provision of a non mag-locked escape is still necessary.”

Additionally it has been indicated that the building offices are not open to the public and staff will be familiar with the operation of the mag-locks using a swipe card access entry system.

Having carefully considered all the information submitted in this case, it is the view of Scottish Ministers that the proposals do meet the requirements of Standard 2.9.