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Fire safety design of photovoltaic installations in Norway
By: Reidar Stølen (RISE Fire Research/NTNU, Trondheim, Norway), Brynhild Garberg Olsø (SINTEF, Trondheim, Norway), Ragni Fjellgaard Mikalsen (RISE Fire Research, Trondheim, Norway), Kathinka Leikanger Friquin (SINTEF, Trondheim, Norway)
Implementation of fire safety design of photovoltaic (PV) installations is random for buildings in Norway, according to a recent study published in the Fire Technology journal entitled ‘Factors Affecting the Fire Safety Design of Photovoltaic Installations Under Performance-Based Regulations in Norway’ (https://doi.org/10.1007/s10694-023-01420-9).
In many countries the number of PV installations on buildings is increasing, including Norway. With limited experience with PV installations, performance-based building regulations and a lack of national guidelines, the implementation of fire safety measures for PV installations relies almost entirely upon the experience of the individual fire safety engineers.
Selection of design fire scenarios for a building requires knowledge on which fires that can be expected and will determine which fire hazards the building should be designed to withstand. As an example, fires starting on the roof spreading downwards into the building has been deemed as an uncommon fire (Fiorentini et.al., https://doi.org/10.3303/CET1648072) and is not always considered in the fire safety design of the building. Fire rated building elements like roofs are usually constructed to prevent a fire from spreading from the inside to the exterior. However, this is a highly relevant scenario for buildings with roof-mounted PV installations.
The fire safety designs for five different Norwegian buildings with large PV installations have been studied to determine factors affecting the fire risk analysis for the PV installation. The degree to which the fire hazards related to the PV installation were considered varied greatly between them, and the following factors were identified to influence this:
- Whether the building was first of its kind as a pioneering building.
- Whether the building was built before or after the publication of the 2018 revision of the Norwegian standard for electrical components and systems NEK 400, which is a collection of prescriptive standards.
- The level of knowledge and experience of the fire safety engineer, which in turn affects the use of performance-based engineering tools and the level of detailing in the design and construction phases.
- The degree of integration of the PV installations in the building.
The lack of prescriptive, well-documented fire safe solutions for installing PV on buildings, give fire safety engineers wide flexibility in assessing the fire hazards of the PV installations and whether fire safety measures must be implemented in the design. A similar challenge in Norway is also discussed in a recent study by Lohne et.al. (https://doi.org/10.3390/buildings13051111) on the topic of climate change adaptation of buildings, where the regulation and experience are also lagging behind the development. This challenges the ethical judgements of individual engineering experts in designing safe solutions without the backing of regulations.
Another obstacle found in this study is that the fire safety engineers were not always involved in the design of the PV installations. For several of the buildings the PV installations were not described and planned when the fire safety concept was developed but was included at a later stage. Fire safety engineers have less opportunity to affect the choices made later in the installation phase, especially regarding which fire safety measures are required to keep the fire risk for the building at an acceptable level. A holistic fire safety concept for the buildings should be aimed for, but this is not possible without including the fire safety engineers in the design of the PV installations. In several of the cases it was the supplier of the PV installations who planned the installations and decided which fire safety measures to include. The suppliers do not, however, necessarily have the knowledge and experience of fire safety engineers, or the full understanding of the fire safety concept for the entire building.
As the installation rate of PV on buildings is accelerating in Norway, the need for guidelines that address the most important issues of PV fire safety is evident. Learning from experiences in other countries will also make the transition for Norway less costly.