Ruling No.: 21-16-1590
Application No.: B-2021-01
BUILDING CODE COMMISSION
IN THE MATTER OF Subsection 24(1) of the Building Code Act, S.O. 1992, c. 23, as amended.
AND IN THE MATTER OF Article 3.1.8.7. and Subclause 3.1.8.8A.(2)(a)(iii) of Division B of Regulation 332/12, as amended (“the Building Code”).
AND IN THE MATTER OF an application by S. Grant Hall, Callidus Engineering, for the resolution of a dispute with Peter Kokkoros, Chief Building Official, to determine whether the proposal to waive requirements for smoke dampers in air ducts opening into a public corridor serving suites in a Group C residential occupancy building, provides sufficiency of compliance with Article 3.1.8.7. and Subclause 3.1.8.8A.(2)(a)(iii) of Division B of the Building Code at 195 Dundas Street, London, Ontario.
APPLICANT S. Grant Hall, P.Eng
Callidus Engineering
London, Ontario
RESPONDENT Peter Kokkoros
Chief Building Official
City of London
London, Ontario
PANEL Stephen Wong, Chair
Leszek Muniak
Alexandra Chow
PLACE City of Toronto, Ontario
DATE OF HEARING September 23, 2021
DATE OF RULING September 29, 2021
APPEARANCES S. Grant Hall, P.Eng
Callidus Engineering
London Ontario
The Applicant
Peter Kokkoros
Chief Building Official
City of London
London, Ontario
The Respondent
Drago Macar
Manager of Fire Protection and Plumbing Inspection
City of London
London, Ontario
The Designate for the Respondent
RULING
1. Particulars of Dispute
The Applicant has applied for a building permit under the Building Code Act, 1992, to construct a residential building at 195 Dundas Street, London, Ontario.
The subject building is a new 25-storey building with a Group C residential major occupancy. The building area is 525 m². The building is fully sprinklered and is classified as a high building. The building is of noncombustible construction and is equipped with a standpipe and hose system and a fire alarm system.
The air handling system in the building supplies air from a roof-top unit downward though a service shaft to all of the floors and discharges fresh air into the public corridors on each floor. The fresh air supply duct is provided with fire dampers at the fire separation between the service shaft and the public corridor.
The fresh air supplied to each floor is intended to flow into each suite and be exhausted through the bathroom exhaust fans in each suite.
The dispute between the parties centres on the provision in the building code which requires smoke dampers to be installed in ducts penetrating fire separations serving a public corridor, yet permits the waiver of smoke dampers in ducts that penetrate fire separations serving a public corridor where the ducts function as part of a smoke control system.
More specifically, the building code requires air handling systems that provide make-up air to public corridors serving suites in Group C major occupancies to not shut down automatically upon actuation of the fire alarm system, so as to maintain corridor pressurization.
The dispute before the Commission is whether the proposal to waive requirements for smoke dampers in air ducts opening into a public corridor serving suites in the subject Group C residential occupancy building, provides sufficiency of compliance with Article 3.1.8.7. and Subclause 3.1.8.8A.(2)(a)(iii) of Division B of the Building Code.
2. Provisions in Dispute
Division B
3.1.8.7. Location of Fire Dampers and Smoke Dampers
(1) Except as provided in Article 3.1.8.8., a fire damper having a fire-protection rating conforming to Sentence 3.1.8.4.(2) shall be installed in conformance with Article 3.1.8.9. in ducts or air-transfer openings that penetrate an assembly required to be a fire separation.
(2) Except as provided in Article 3.1.8.8A., a smoke damper or a combination smoke and fire damper shall be installed in conformance with Article 3.1.8.9A. in ducts or air-transfer openings that penetrate an assembly required to be a fire separation, where the fire separation,
(a) separates a public corridor,
(b) contains an egress door referred to in Sentence 3.4.2.4.(2),
(c) serves an assembly, care, care and treatment, detention or residential occupancy, or
(d) is installed to meet the requirements of Clause 3.3.1.7.(1)(b) or Sentence 3.3.3.5.(4) or 3.3.4.11.(4).
3.1.8.8A. Smoke Dampers Waived
(2) The requirement for smoke dampers or combination smoke and fire dampers described in Sentence 3.1.8.7.(2) is permitted to be waived for noncombustible branch ducts having a melting point above 760°C that penetrate a fire separation,
(a) provided the ducts,
(i) have a cross-sectional area not more than 130 cm² and serve only air conditioning units or combined air-conditioning and heating units discharging air not more than 1.2 m above the floor,
(ii) extend not less than 500 mm inside exhaust duct risers that are under negative pressure and in which the airflow is upward as required by Article 3.6.3.4., or
(iii) are required to function as part of a smoke control system, or
(b) provided the fire separation separates a vertical service space from the remainder of the building and provided each individual duct exhausts directly to the outdoors at the top of the vertical service space.
3. Applicant’s Position
The Applicant submitted that the requirement for smoke dampers to be installed in ducts that penetrate a fire separation that separates a public corridor is permitted to be waived, provided the ducts are required to function as part of a smoke control system.
The Applicant argued that the make-up air system that serves the public corridors functions as a smoke control system for the following reasons:
The intent of the Building Code is that a corridor make-up air system becomes an emergency pressurization system at the moment that there is an emergency fire condition in the building,
The operation of the public corridor make-up air unit serving suites in a Group C residential occupancy is prescribed in Article 3.2.6.2. “Limits to Smoke Movement” to continue to operate to maintain corridor pressurization upon initiation of the fire alarm system as per Sentence 3.2.6.2.(5.1) and that it is required to be powered from an emergency power supply as per Clause 3.2.7.9.(1)(c), thus qualifying it as an emergency system,
The corridor make-up air system changes its purpose upon initiation of the fire alarm, it is now considered to be part of a smoke control system and therefore the exemption found under Subclause 3.1.8.8A.(2)(a)(iii) is applicable to this situation,
The simpler and more economical approach is to install a duct-type smoke detector in the supply air stream of the make-up air unit to shut down the air supply from the unit upon detection of smoke in the supply air stream. That would achieve an equal outcome as the installation of smoke damper installed at every public corridor penetration at every floor level in the building, since there is generally only one source for the supply air, the outdoor air, and
Table 1.3.1.2. of Division B of the Building Code references standard CAN/ULC-S1001, “Integrated Systems Testing of Fire Protection and Life Safety Systems”. CAN/ULC-S1001 defines Emergency Pressurization System as a ‘smoke control system’ in its glossary of terms.
The Applicant submitted that a corridor pressurization system is a smoke control system in that it dilutes the smoke that is in the corridors and provides pressurized corridor air, thereby preventing smoke from migrating from a suite into the corridor. As such, the supply air ducts serving the public corridors are exempt from the installation of smoke dampers at the point of penetration into the public corridor.
In addition, the Applicant indicated that by not installing smoke dampers in the supply-air ducts, conformance with the requirement of the Building Code for not shutting down corridor air supply systems automatically will be achieved.
Upon questioning, the Applicant confirmed that he did not reference the Objectives and Functional Statements applicable to the disputed Building Code Article and Subclause.
The Applicant was requested to provide details regarding the pressure gradient differences between the public corridor and the suites and the air-flow rates of supply air into the public corridor on each floor. The Applicant provided part of the requested information after referencing the air flow design calculations and indicated that the air flow through the public corridor is capable of providing 6 air changes per hour within the corridor. Information regarding air exchange rates within the entire floor and the pressure differences across fire separations and between stories of the building was not provided.
4. Respondent’s Position
The Designate for the Respondent submitted that no smoke control system is proposed to be installed. The Applicant considers the corridor make-up air system to also function as a smoke control system alone.
The Designate submitted that a smoke control system is not a defined term under the Building Code. Based on good engineering practice, the City of London Building Division believes that a smoke control system in a Group C residential major occupancy high building, would be an air-handling system, specifically designed, engineered and installed to react to fire or smoke conditions either automatically or via manual means. This special safety operation would provide the ability of shutting down the air supply to any single storey involved, while activating exhaust air from that storey when required. Electrically controlled dampers must be utilized to achieve such an operation.
It was the Respondent’s opinion that the proposed make-up air system, as shown by the Applicant for the public corridors, is just a ventilation system. The Respondent indicated that the public corridor make-up air system could be considered as a part of a smoke control system when designed as described above, but it cannot be considered to function as an entire and complete smoke control system on its own. As such, the supply air ducts need to be provided with smoke dampers.
5. Commission Ruling
It is the decision of the Building Code Commission that the proposal to waive requirements for smoke dampers in air ducts opening into a public corridor serving suites in a Group C residential occupancy building, does not provide sufficiency of compliance with Article 3.1.8.7 and Subclause 3.1.8.8A.(2)(a)(iii) of Division B of the Building Code at 195 Dundas Street, London, Ontario.
6. Reason
i) Sentence 3.1.8.7.(1) of Division B of the Building Code sets out the requirements for where fire dampers are to be installed. Both parties did not disagree with the requirement that fire dampers are required. Therefore, this Sentence is not in dispute.
ii) Sentence 3.1.8.7.(2) of Division B of the Building Code requires smoke dampers or combination smoke and fire dampers to be installed where ducts penetrate a fire separation that separates a public corridor. The parties did not disagree with the requirement that smoke dampers or combination smoke and fire dampers are required. However, the Applicant indicated only fire dampers need to be installed since he is of the opinion that the public corridor make-up air system meets the conditions for the exception given in this Sentence. Therefore, the dispute is in regard to the application of the exception described in Article 3.1.8.8A. “Smoke Dampers Waived” as referenced in Sentence 3.1.8.7.(2).
Article 3.1.8.8A. “Smoke Dampers Waived” of Division B of the Building Code sets out the conditions for where smoke dampers or combination smoke and fire dampers in ducts as described in Sentence 3.1.8.7.(2) are permitted to be waived. One of the requirements as stated in Subclause 3.1.8.8A.(2)(iii) requires the ducts “to function as part of a smoke control system”.
The Commission notes that the building is a high building and Article 3.2.6.2. “Limits to Smoke Movement” is applicable.
Based on the evidence and testimony, it is the Commission’s opinion that the Applicant did not adequately demonstrate that a mechanical air moving system, intended to actively remove smoke from a fire floor and prevent it from moving throughout the building in a controlled and coordinated manner, as required by Article 3.2.6.2. and described in MMHA Supplementary Standard SB-4, “Measures for Fire Safety in Hight Buildings”, was specifically engineered for this building. It is also the opinion of the Commission that a make-up air supply system on its own is not a complete smoke control system required for a high building. Therefore, the Commission is of the opinion that sufficiency of compliance with Sentence 3.1.8.7.(2) and Subclause 3.1.8.8A.(2)(a)(iii) of Division B of the Building Code has not been achieved.
iii) The Applicant failed to demonstrate that the proposed make-up air supply system will limit the danger to building occupants and firefighters from exposure to smoke and other hazards to life safety in the event of a building fire.
Dated at the City of Toronto this 29th day in the month of September in the year 2021 for application number B-2021-01.
Stephen Wong, Chair
Leszek Muniak
Alexandra Chow