Reducing fire risk to zero would cost huge amount, Tai Po blaze inquiry hears

Requiring that only incombustible materials be used for large-scale renovations at housing estates is unrealistic and fails to take into account risks that arise after prolonged use, a public inquiry into Hong Kong’s deadliest inferno in decades has heard.
The use of polyfoam boards to seal windows was among five key factors that led to the death toll of 168 people at Wang Fuk Court in Tai Po last year, experts said at the public inquiry session on Wednesday.
An expert appointed by the government said it would be impossible to eliminate the risk of fire at estates undergoing renovation work simply by banning the use of combustible materials near light wells.
“It’s a matter of risk management,” said Richard Yuen Kwok-kit, chair professor of architectural engineering at City University.
“We want to minimise the risk as far as practicable, but to reduce the risk to zero would require a huge price, which is impossible.”
Yuen explained that even fire-retardant scaffolding mesh and polyfoam boards would deteriorate over time.
He noted that an interdepartmental investigation task force set up to investigate the blaze had not examined the durability of safety nets or plastic coverings if they became brittle after prolonged use.
Former lawmaker Chan Kin-por, a member of the independent committee conducting the public inquiry, also said that construction costs would skyrocket if only incombustible materials were allowed in renovation projects.
“That’s not feasible in principle,” he said.
Committee chairman Mr Justice David Lok Kai-hong said that impractical recommendations by the committee could not help solve the problems at hand.
“Any recommendations would affect the industry’s interests,” he said. “At this stage, we have to make them aware of those risks and set a policy direction.”
The committee continued to hear evidence on the possible causes of the deadliest fire in Hong Kong since 1948 and factors contributing to its rapid spread across seven of the eight 31-storey towers at Wang Fuk Court.
The 43-hour blaze broke out on November 26 last year as the subsidised housing estate was undergoing an exterior overhaul.

Yuen said the findings of computer simulations and physical tests supported the theory that the use of non-fire-retardant scaffolding mesh helped the fire to spread quickly by igniting other combustible materials at the site.
The task force conducted 13 tests using a three-storey replica of Wang Cheong House’s light well, including renovation materials, at the Sichuan University of Science and Engineering.
In one test, open flames were visible after half an hour and the fire surged to the top of the structure within minutes.
The tests also showed that burning droplets of non-fire-rated scaffolding mesh could ignite other combustibles, including toe-boards on working platforms of scaffolds, wooden planks and bamboo poles.
Yuen pointed out that while bamboo was difficult to ignite, it released significant energy once on fire and had led to the “exponential” growth of the blaze.
An experiment carried out with safety nets collected from Wang Chi House – the estate’s only undamaged building – and bamboo scaffolding recorded nearly 573kg (17.7lbs) of burned bamboo, releasing 8,720 megajoules of energy, which accounted for 85.9 per cent of the total heat released.
Only 8kg of bamboo was incinerated when fire-rated mesh was used, the committee heard.
According to computational fluid dynamics simulations, embers spread from Wang Cheong House to nearby blocks when the blaze started on November 26, a day marked by dry weather and strong winds.
Separate tests on scaffolding nets found that the fire retardancy of those retrieved from Wang Chi House was even worse than non-fire-rated samples, showing the mesh used very likely lacked any fire resistance.
Fire services divisional commander To Chi-wing, the task force’s secretary, said the flames first spread vertically along the outer walls of Wang Cheong House before its interior and adjacent towers were set alight.
He noted that the plastic sheets used at the estate had very poor fire-retardant properties and had likely exacerbated the blaze.

Of the 1,984 flats at Wang Fuk Court, 560 sustained severe damage, 518 of which were located near the buildings’ light wells.
To said the numbers corroborated survivors’ accounts and scientific findings that the fire first entered the flats through the kitchens facing the light wells.
Assistant director of fire services Yiu Men-yeung, the task force head, attributed the disaster’s high death toll to five factors: the rapid spread of the blaze, unlawful alterations to evacuation staircases, the deactivation of fire alarms, falling debris and windows fitted with polyfoam boards.
The witness said people trapped in a fire should assess the possible dangers when evaluating evacuation, pointing out that no exit strategy could guarantee survival.
“Throughout my 28 years in the fire service, the question that I have been asked the most is: should I escape or not?” he said. “It is always right to attempt to evacuate, but whether you should insist on evacuation depends on a dynamic assessment.”
Yiu also commented on Ho Wai-ho, the firefighter who died in the blaze, saying the task force determined that the late officer had complied with internal guidelines throughout the operation.
Fighting back tears, Yiu also pointed out that Ho could have left the building but chose to save lives.
Two committee experts will testify at City Gallery in Central on Thursday regarding the causes of the disaster.
The hearing will be conducted in English. A live broadcast with Cantonese interpretation will be available at the Central Library in Causeway Bay.