En effektiv utforming av brannsikkerhet krever kunnskap i alle ledd

For at fagpersoner skal ta effektive beslutninger i et bygningsprosjekt, om det er relatert til brann eller ikke, må alle faktorer som påvirker brannsikkerheten vurderes. Derfor er det viktig at alle de involverte; fra arkitekt, bygningsansvarlig og fagpersoner innen brannsikkerhet, er på samme side av banen når det kommer til selve tilnærmingen til prosjektet. Dette bør skje allerede i planleggingsfasen av bygget.

Publisert

It is needed to properly define the attributes, influencing a building’s fire safety performance, for the professionals in a buildingdesign project. These attributes can be mainly separated into the 3 main design stages, while observing how decisions in each of them would affect the resulting overall fire safety of the building.

Phase 1: Design Brief

· Building Regulations

Buildings are supposed to be designed while abiding by regulations, and thus those regulations should be checked before starting with the design process. In addition, designers might not realize that it’s possible to resort to performance-based comprehensive approaches to fire safety, which in turn provides major flexibility for the design. This issue can be due to the fact that building officials prefer prescriptive solutions and may thus restrict the use of performance-based design. Thus, it is essential that all those responsible (building officials, designers, and fire safety professionals) are on the same page when it comes to the approach to be used, even before initiating the actual building design.

· Occupancy/overall building floor area/height

Occupancy, purpose groups, or building use are very critical for fire safety as they basically determine the characteristics of prospective users and the probability of fires that could develop in the building. Thus, once the occupancy is decided upon, fire safety engineers should be included to make sure that the architects are aware about the required characteristics of that specific occupancy.

· Environmental conditions (temperature, wind, humidity, flood, hurricane, vegetation, soil, hydrology, seismic zones)

Environmental conditions can highly affect fire safety performance. For example, wind direction influences the movement of smoke and flame spread within a building, besides either helping or opposing firefighters in their rescue mission. Thus, it needs to be considered, especially in areas or geographic locations where consistent and strong wind is to be expected.

· Communal environment (rural, urban, tourism, large city, existing structure)

High proximity and preparedness of fire brigades is beneficial to fire safety. However, that’s not always possible due to limitations in both manpower and appliances. This might require internal fire protection systems and studies investigating fire propagation especially in dense areas. This also poses the importance of façade materials, buffer zones and separation distances, location and sizes of openings, among other factors.

· Infrastructures (traffic, gas, electricity, water)

In cases where water resources are limited, separate sources should be provided for internal and external firefighting measures, as well as providing reliable power sources for active fire protection. Moreover, electricity, if poorly maintained, can act as a major ignition source. Traffic, on the other hand, can highly affect the anticipated response times for fire brigades and ambulances. Thus, stricter internal fire measures should be placed in areas with high traffic.

· Site history and historical value

Restrictions on historical sites can affect the surrounding roads and emergency response times and accessibility. Furthermore, limitations on choice of materials can apply based on required harmony with existing surrounding historical buildings, which in turn may not possess enough fire safety characteristics as their modern substitutes.

Phase 2: Schematic design/ Concept Development

· Project objectives and design concept

Design solutions to achieve the intended project objectives are decided upon in the schematic design and concept development phase. For instance, if the building is supposed to achieve a green design ad high level of sustainability, approaches such as using eco-friendly materials, solar systems, double façades, and such are determined in this phase. In that case, fire hazards stemming from these approaches would need to be investigated early on.

· Building orientation and schematic site design

The site design (including the building’s orientation) is affected by required views (to and from the building), daylight conditions, site typology, access routes, among others. However, when it comes to fire conditions, the relative direction of the building entrance to other existing buildings, parking lots, and fire fighters’ access routes are vital features for fire safety performance as they can determine the occupants’ egress direction and the effectiveness of rescue activities. Assembly areas outside the building should also be sized according to the expected number of occupants.

· Occupant flow or circulation (parking, elevators, escalators, stairs)

Occupant flow and circulation paths used in normal working conditions are essential, as occupants will tend to use the same pathways in the case of an emergency. Secondary egress routes should be accessed easily from the elevator area, and architectural features and defining spaces play an important role in that.

· Spatial design and schematic space allocation

In spaces where large or fast developing fires are expected, smaller scaled spaces are desirable. As fuel quantities are linked to space size, higher heat release rates are obtained in larger spaces over shorter periods, specifically those with low ceilings. Danger of ignition is also affected by space use. Location of rooms is very important as well, as flames tend to spread easier horizontally than vertically, lower floors are somehow safer when high risk areas are placed on higher floors. Furthermore, rooms which are expected to host large numbers of people simultaneously should be placed on ground levels with direct egress paths to the outdoors.

Stage 3: Design development

· Site plan and landscaping

Within this phase, further details for the site plan and landscaping are determined, including hydrant locations, firefighter’s access routes, police control lines, and possible blockages of those. It should also be considered that building ornaments, sculptures, and vegetation would not add up to existing fuel amounts, ignition possibilities, or hinder evacuation or emergency response.

· Floor plans and sections

Exit locations are to be determined according to occupants’ use and their respective characteristics. At least two distant exists should be put available, in case one of them is blocked or fails. In case only one of the exits is expected to be used in emergencies, that indicates issues with the floor plan itself. Fire protection systems in place could also affect the number of exits needed. Moreover, spaces expected to host large numbers of people or specific type of activities might need different measures. Occupancies with low familiarity levels (hotels, airports, etc.) should have extremely clear signage and spatial configurations for easy wayfinding.

· Structural system and roof system

Structural integrity is major role player in safekeeping firefighters’ lives, as structural failure will usually take place during their mission. Innovative structural systems should also consider the structural performance in fire conditions, besides normal operations, and their effect on firefighters. An example would be in the employment of green roofs (with vegetation) or solar powered panels, and such technologies.

· Building envelope design

One of the major issues in fire safety is fire spread throughout the building envelope, posing threats of flames reaching nearby floors through openings. For that, adjacent openings should be provided with enough vertical separation distance or long enough spandrels such that vertical flame spread is less likely along the building envelope. The geometry of the façade also plays a role in flame spread, as outwardly slanted surfaces contribute to flame movement. Equipment placed on rooftops (advertisement panels, HVAC units, etc.) can add to the dangers of short circuiting and might cause a difficult to detect fire or contribute to an already existing one. Fire can also spread downwards through burning falling objects.

· Interior finishes

As interior finishes are not there solely for their combustibility characteristics, aesthetics play a major role in their choice. Colors, textures, acoustic performance, all are parts of how occupants perceive the relevant space and recognize locations within a building, as well as aiding in orientation to exit routes.

How to translate those guidelines?

As we have seen that lots of elements in architectural design can have major impact on fire safety, it be precise to say that collaboration between architects and fire engineers can create better buildings. Working together, architects and engineers can come up with design solutions that are better than their individual ones. Exchanging knowledge and information, especially at the early stages of a project, eventually leads to better buildings.

Architects might have a limited knowledge in the availability of options for fire safety design, be it prescriptive, performance based, or a mixture, besides continuous developments in fire science and simulation technologies. Furthermore, they might not be fully aware of how their different design features can affect the fire safety performance of a building. Thus, Fire Protection Engineers should help architects understand their role in fire safety, while recognizing them as key players in that, as they could – relatively easily- embed fire safety design into their architectural approach.

Litt om journalisten:

Amani er en libanesisk arkitektingeniør med en spesiell interesse for fagfeltet sikkerhet. Hun har også en Mastergrad i brannsikkerhet fra Høgskulen på Vestlandet (HVL), som hun var ferdig med i 2020. Hun har siden begynnelsen av 2021 jobbet som Graduate Fire Engineer ved Arup UK, og skriver med brennende engasjement for Brennaktuelt.no på fritiden.

References:

Meacham, B., & Rodriguez, A. (2014). Risk-Informed Performance-Based Design for Fire: Concepts & Framework. National Institute of Standards and Technology, U.S. Department of Commerce. Worcester: Department of Fire Protection Engineering, Worcester Polytechnic Institute.

Park, H., Meacham, B., Dembsey, N., & Goulthorpe, M. (2014, November). Integration of Fire safety and Building Design. Building Research and Information, 42, 6. doi:10.1080/09613218.2014.913452

Ulfsnes, M. K., & Danielsen, U. (2004). Ivaretakelse av branntekniske krav i byggeprosessen. Trondheim: SINTEF.

Webb, S. (2019, October 24). Why buildings are better when architects and engineers collaborate. (N. Morris, Interviewer) RIBA Practice Team.