Little National Hotel

Currently under construction, Little National Hotel promises to offer local and international travellers a luxurious escape in the heart of Sydney CBD. Utilizing the existing Wynyard Walk structure above Wynyard Station, the hotel boasts 230 contemporary rooms enveloped by a striking curved façade and vertical garden. Guests have access to a modern gym, library and exclusive rooftop lounge and bar with city views.

The hotel structure comprises a steel-framed structure with a composite steel-concrete floor system. Holmes’ team of structural fire engineers, in collaboration with the structural engineers’ team from TTW, developed a unique optimised fire protection strategy for the steel structure. Holmes was able to demonstrate via an advanced thermal and structural fire analysis, utilising non-linear finite element software, that the structural frame with an optimised fire protection strategy can maintain structural stability throughout the entirety of a credible fire scenario. This resulted in major cost savings for the client, as the solution allowed for reduced passive protection of steel members, reducing material and labour costs.

In addition to the structural fire assessment, a number of Performance Solutions were required to support the design intent of the building. These included, for example, reduced fire resistance levels to particular areas, external separation of fire compartments, service penetrations through fire rated elements, travel distances to exits, egress width, stair discharge, protection of fire hydrant booster etc. Holmes also analysed any potential impact the fire strategy of the new hotel may have on the existing Wynyard Walk building and helped enable the two buildings having some combined fire services.

One particular challenge faced in this project was the proposed design option of having an external stair instead of an enclosed fire-isolated stair serving levels above 25m in height. This is not permitted in the BCA Deemed-to-Satisfy compliant provisions due to the risk that people would suffer vertigo and the risk that weather conditions, particularly wind, may become more severe above this height. Holmes helped enable this design by performing a detailed analysis of the wind effects on the external stair to show that the wind velocity wouldn’t impact occupant evacuation conditions.