Client: CEM Project Management SA
Project Leader: Richard Forrest BSc MBA, Director
Project Support: Richard Godwin CEng MIStructE MIFireE, Senior Project Fire Engineer
Type of works: application of fire-engineering techniques and integration of fire safety strategies, definition of strategic project approach, liaison with client departments and other third parties. Quality Assurance review, authorship of report, design, support and Spanish fire safety standard equivalency review.
Lawrence Webster Forrest (LWF) was initially appointed fire engineers to the design of a new shopping centre in Madrid, then subsequently appointed to the design team for the integrated Snow Dome. The objective was to rationalise the onerous fire safety requirements of the Spanish Normatives by applying fire engineering techniques, and also to closely integrate the fire safety strategies for both the shopping centre and Snow Dome. The Snow Dome represents a 240m ski slope of artificial snow with ancillary warm areas for changing and acclimatising from -5 to 40°C.
LWF was appointed by project manager CEM to work with the design team on a new entertainment complex that brings winter to Madrid, 365 days a year. The development of an indoor skiing facility, Snowdome, forms part of an overall retail and entertainment development as part of the new Xanadu Shopping Centre, Madrid, Spain, accessed from the N5.
The project in question is the development of a skiing facility for use by the general public comprising the main skiing area (single story built on a slope) with associated changing facilities. Administration accommodation is provided on an adjacent first-floor level. There is also an adjacent restaurant/bar/discotheque area that is linked to the main shopping complex development and the skiing area, offering a panoramic view of the slopes while enjoying the warmth.
The design of the facility allows for a 240m long straight run from top of the slope to the chair lift base.
The ski area and plant occupy a gross floor area of 16,200m2. The ancillary warm areas of the ground and first floor occupy approximately 3,000m2. The skiing facility is designed for a maximum of 750 persons on the slopes alone.
As the approach of performance-based fire engineering was not described in the Spanish regulations, the first consideration was to identify the approach proposed for consideration by the project team for consultation with CAM Bomberos (Madrid Fire Brigade). As this was part of the first such project in Madrid that followed deviations from the normative with engineering justifications, communication of the process was a key element for a successful design.
From LWF's initial review of the development it was apparent that three fundamental issues existed:
The building contents had very limited fire load when considered over the entire area. Localised risk areas existed which required specific considerations. Adoption of a fire rated structure, sprinkler system and smoke venting throughout would add little benefit to a safer environment.
Although the risks of fire could be managed, the occupants themselves would not follow a normal egress situation. Many people would be in a family environment, therefore any emergency would prompt a gathering of family before evacuation. Occupants would be wearing thick heavy clothing, carrying skis, poles, snowboards, and trying to evacuate with their possessions. Footwear would comprise stiff shin-high boots that make descending steep stairs slow and dangerous. Occupants may be on a chair lift suspended in the air in event of an emergency.
Although the fuel load itself was limited, the typical construction of cold environments incorporates wall and ceiling panels that potentially allow for a fire to spread within the cavity panels. The inappropriate choice of these panels in the past has resulted in the death of firefighters in Europe.
To address all these issues necessitated an alternative fire engineering approach using performance-based solutions particularly in respect of the movement of smoke and the safe evacuation of occupants.
A full Available Safe Egress Time (ASET) Vs Required Safe Egress Time (RSET) assessment was undertaken where the RSET considered all the required factors including pre-movement of occupants. Rather than using the sophisticated visual graphic tools, hand calculations were used to present the calculations since this was a new concept to the approval authorities it was important to outline how answers were derived as opposed to simply entering data into a computer model. As with smoke modelling a practical consideration of the evacuation simplified the scenario, as the number of converging streams of occupants was minimal.
The differing fire scenarios were collated and assessed in comparison with occupants' evacuation to demonstrate that the occupants could safely evacuate from the area in all probable fire scenarios.