“Are South African Buildings as Safe as New Zealand Buildings?” A person going into or using a building anywhere in the world has certain expectations as to the perceived and acceptable level of risk to life safety. There are also societal expectations and acceptability levels which are perhaps not explicitly stated. Building legislation in both New Zealand and South Africa appear to have similar goals, yet when applying the relative prescriptive document to a similar building in each country the perception is that one country has a higher level of safety over the other. Having worked for a number of years under both sets of building design regimes, the author was of the opinion that aspects of one prescriptive document has more stringent requirements than the other and that buildings in the one country thus had a higher apparent level of life safety than the other. The question was asked: How much difference is there in (fire) life safety for an occupant of a building in New Zealand compared to a building in South Africa? Is a similar building designed to a higher standard in one country as opposed to the other? To test the author‟s hypothesis in a measured way a scoring system was required to quantify the relative level of safety. The comparison is carried out using the Fire Safety Index scoring system developed by McGhie. A spreadsheet analysis is carried out for similar building types (Building Use, Height, Fire Load and Number of Occupants) complying with each country‟s relevant acceptable solution or deemed-to-satisfy document using McGhie‟s weighted risk ranking model. Buildings are assessed across four Building Use Parameters (Purpose Group, Escape Height, Occupant Numbers and Fire Hazard Category). As the buildings assessed are very similar, the Building Use Scores are virtually identical; with some variations, for example, when occupant numbers are capped because of limitations on fire cell floor areas. The Fire Safety Features Score for each building is then assessed for the minimum requirements of the prescriptive documents across eight main category headings (Fire Barriers, Fire Alarm, Smoke Control, Building Fire Control, Emergency Power Supply, Communication System, Fire Service and Means of Escape) and a number of sub-categories. Once the attribute score is assigned and the ii weighting applied the total score is summed and a numerical rating score is achieved for each building out of a possible maximum score of 5. As approximately 63% of commercial buildings (in NZ) are single storey and a further 28% are two-storey‟s high, the discussion of the differences in score between the two sets of buildings will primarily focus on one and two storey buildings, and the scoring is weighted to account for the relative building stock, with averaging used for the various occupant loads. The results show that for equivalent Working Purpose groups (WL), Mercantile Occupancies (CM) and Residential Occupancies (SR) the South African buildings are safer than the New Zealand buildings. Occupancies which are Crowd Activities (CL) and Sleeping Accommodation (SA) are safer in New Zealand than in South Africa. The Working Moderate fire load (WM) occupancy is rated equal for both countries.

This research project aims to investigate the level of risk/safety inherent in intermediate floors of buildings designed to the Compliance Document for the New Zealand Building Code, Fire Safety Clauses C1, C2, C3, C4 (C/AS1), and develop guidance for Fire Engineers on designing fire safety for firecells containing intermediate floors. The project also aims to develop a new set of prescriptive fire safety requirements for intermediate floors and proposes an outline of a verification method for designing fire safety for intermediate floors. This study includes a literature review of the fire safety requirements for intermediate floors (mezzanines) of prescriptive requirements in New Zealand and other countries such as USA, Canada, UK and Australia. The results of this literature review found that the intermediate floor size is limited and varies with country. An intermediate floor that has an area exceeding the limit set out by the prescriptive requirements is considered as a storey in all the countries prescriptive requirements reviewed including the New Zealand prescriptive requirements prior to 1991. Since 1991, in New Zealand Acceptable Solutions, the intermediate floor that has an area exceeding the limit will not be treated as a storey, however, a smoke control system is required. The level of risk was quantified using a factor of safety (FoS) - the ratio of Available Safe Egress Time (ASET) to Required Safe Egress Time (RSET). Two fire models; BRANZFIRE and FDS were used to calculate ASET and SIMULEX, an evacuation program, was used to calculate movement times of the occupants of the studied buildings. Unlike the traditional method in which RSET and FoS are assessed using single value, in this project the distribution of RSET and FoS were assessed using the @RISK software package. The analysis showed that the level of risk to the occupants of the firecells containing intermediate floors is always higher than that of the equivalent firecells without intermediate floors with the same occupant load and the differences in FoS range from 10% to 60%. The analysis also highlighted that the level of risk to the occupants of firecells having intermediate floors increases as the intermediate floor size increases, however, there are no clear cut-off points at which a higher level of fire safety precaution should be provided. The cut-off points in C/AS1 of 20% for a closed intermediate floor and 40% for an open intermediate floor, are not justified by this analysis. Occupant load has significant impact on the level of safety of the occupants of the firecells containing intermediate floors. The higher the occupant load the lower the level of safety is. The definitions for open and closed intermediate floors are proposed to which open and closed intermediate floors are clearly distinguished. The term “limited area intermediate floor” in the current C/AS1 is proposed be removed and all related clauses are proposed to be amended or deleted accordingly. A proposed new set of prescriptive fire safety requirements for intermediate floors has been developed based on the occupant load of intermediate floors and not the intermediate floor size in the form of a table similar to the current Table 4.1 of C/AS1. The occupant load and fire safety precautions (FSPs) of the intermediate floors are determined based on the occupant load and their required FSPs of the equivalent firecells without intermediate floors that have the same factor of safety with the firecells containing intermediate floors. With the proposed FSPs, a firecell with lower occupant load would require lesser fire safety requirements than a firecell with higher occupant load regardless of intermediate floor size. Moreover, with the proposed FSPs for intermediate floors, the level of safety of the occupants of the firecells having intermediate floors would be very similar to the level of safety of the equivalent firecells without intermediate floors. In addition to the proposed tables of FSPs, some clauses regarding the changes in the fire safety requirement and definitions for intermediate floors are proposed. Guidance for designers in designing fire safety for firecells containing intermediate floors in which the methods of modelling using BRANZFIRE and Fire Dynamics Simulator (FDS) are presented in detail, has been developed. The analysis has pointed out that the location of the exits is critical in designing fire safety for firecells containing intermediate floors and majority of exits from the lower floor should not be located under intermediate floors. Although one of the main objectives of this research project was to propose an outline of a verification method for designing fire safety for intermediate floors, the analysis showed that it is very difficult to develop a rational verification method for designing fire safety for firecells containing intermediate floors. Using the proposed FSPs for intermediate floors which are based on the occupant load of the intermediate floors in designing fire safety for firecells containing intermediate floors is recommended by this study. These recommendations do not preclude the use of specific fire engineering design for designing fire safety for firecells having intermediate floors.

Performance-based fire engineering design is becoming a more common practice for fire safety design of large complex buildings and modifying existing buildings. However, different engineering assumptions and ambiguous acceptance criteria not only lead to inconsistent level of safety, but also cause inefficient Building Consent process and can result in expensive appeals. In August 2006 the New Zealand Department of Building and Housing (DBH) has been developing a Verification Method (C/VM2) for demonstrating compliance with the Fire Safety requirements of the New Zealand Building Code (C Clauses). This research evaluated the proposed C/VM2 on four complex buildings, including Multi-level Night Club, Hospital, Shopping Mall and Retail Warehouse. It has showed that the C/VM2 successfully implements a systematic and less ambiguous guidance for the future performance-based fire safety designs. However, continued analysis and development is necessary that a solely deterministic method may not be the best solution. A risk-based concept is suggested to be incorporated into the new generation of the C/VM2.