Cold Climate Fire Risk; A Case Study of the Lærdalsøyri Fire, January 2014

Abstract

Abstract. Parameters leading to the severity of the fire in Laerdalsøyri, Norway, January 18th to 19th 2014, have been analyzed. The fire in the first villa developed significantly faster than the fire fighters could handle and the fire quickly spread to other structures. In addition to 36 modern buildings, 4 historic buildings in Gamle Laerdalsøyri cultural heritage area were lost. Heroic effort of local and neighbor community fire brigades, police, military forces and volunteers prevented the fire from destroying the whole village, including the remaining 157 historic buildings. Adiabatically heated (low humidity) air from surrounding high mountains gave outdoor wood fuel moisture content (FMC) of about 7.6%. Inside inhabited buildings, it is shown that the wooden products reached about 4.5% FMC prior to the blaze. When ignited, this resulted in rapid fire development. Two story villas burned down in less than 1 h while producing much embers and firebrands. Strong shifting winds subsequently spread the fire to neighbor houses by flame contact (periodically 20 m long horizontal flames) and over long distances (200 m) by embers and firebrands. Based on the present work, an increased fire risk associated with low FMC in inhabited wooden houses during winter time can be predicted. This is of value when considering measures to reduce the probability of a fire outbreak as well as measures mitigating the escalation of a potential fire.

Cold Climate Structural Fire Danger Rating System?

“…The ambient temperature and relative humidity for this meteorological station are shown in Figure 1. Theoretically estimated indoor relative humidity, based on the values in Figure 1 and the calculation procedure explained in [9], is shown in Figure 2. The buffering effect of the wooden materials and the moisture gain from indoor Challenges 2018, 9, 12 3 of 15 activities are not taken into consideration.…”

“…The characteristics of these three fires based on references [4,9,17] are summarized in Table 1 with their corresponding wood Equilibrium Moisture Content (EMC). As fire testing of wood As seen in Figure 2, the theoretically calculated relative humidity was very low about 10 days prior to the Skinnarberga senior home and care center fire.…”

“…The characteristics of these three fires based on references [4,9,17] are summarized in Table 1 with their corresponding wood Equilibrium Moisture Content (EMC). As fire testing of wood specimens, e.g., in a cone calorimeter, is usually performed with samples conditioned to equilibrium mass at 50% RH (±5% RH), the corresponding EMC value for 50% RH is included in Table 1.…”

“…As fire testing of wood specimens, e.g., in a cone calorimeter, is usually performed with samples conditioned to equilibrium mass at 50% RH (±5% RH), the corresponding EMC value for 50% RH is included in Table 1. In the normal (50% RH) condition, the 9.3% water contained in the wood slows the fire development in several ways and particularly due to the heat needed to evaporate the water vapor [9]. Less water in the wood when exposed to a drier indoor climate, as indicated in Table 1, increases the fire risk in cold climates.…”

“…However, the increased fire frequency may not tell the complete story. The intensity of a fire, i.e., increased by low Fuel Moisture Content (FMC), is also important [9,10]. Such effects are discussed in the recent work by Ayoub et al [11], who showed that the hospitalization risk for fire-related burns increases during extreme cold weather in Canada.…”