Consumer Grade Weather Stations for Wooden Structure Fire Risk Assessment

Area of Science:

• Environmental Science
• Building Science
• Fire Safety Engineering

Background:

• Unusually cold and dry weather in Norway during January 2014 led to critically low indoor relative humidity (RH) in heated wooden homes.
• This low RH resulted in dry wood, a significant factor in Norway's two most severe accidental fires since 1923.

Purpose of the Study:

• To evaluate the efficacy of low-cost, consumer-grade weather stations for monitoring temperature and relative humidity.
• To assess the potential of these stations as a proxy for evaluating dry wood structural fire risk.

Main Methods:

• Calibration of weather station relative humidity (RH) sensors using saturated salt solutions (LiCl, MgCl₂, NaCl) across an 11%-75% RH range.
• Deployment of calibrated weather stations in the living rooms of eight wooden buildings during the 2015/2016 winter.
• Comparison of outdoor sensor data with a local meteorological station and humidity forecasts.

Main Results:

• Calibrated weather stations demonstrated accuracy within ±3% RH.
• A period of significantly increased fire risk was identified in January 2016 based on recorded indoor conditions.
• Outdoor sensor data correlated well with meteorological station readings, with localized variations noted (e.g., proximity to the sea).

Conclusions:

• Low-cost weather stations provide reliable measurements for indoor RH and temperature.
• This technology can serve as a valuable tool for assessing dry wood fire risk in residential buildings.
• Weather station data and forecasts show promise for early fire risk identification.