The need to build a more sustainable future leads us to reduce human greenhouse gas emissions and energy consumption. The building sector is one of the biggest emitters of greenhouse gases (over 120 million tons CO2eq/year in France). Besides, requirements in terms of comfort and air quality continuously increase to achieve the target of healthy and sustainable buildings. Therefore, there is no denying the urgent need to develop new bio-based materials with the smallest ecological footprint and at the same time complying with Indoor Air Quality (IAQ) standards. Bio-based construction materials produced through more energy efficient and less CO2eq emissive process, vapothermal curing, are good candidates to address this challenge. Nevertheless, they have to be validated from an IAQ point of view. Fungi development on their surfaces, a source of microbial volatile organic compounds (mVOC) may deteriorate the air quality and induce odour nuisances. Fungi might be more likely to colonize bio-based materials as their high organic content presents sources of nutrients. This work assesses the impact on IAQ of two new hemp and flax based construction bio-materials. Each of these is evaluated in an emission chamber for 28 days at three relative humidities (50, 75 and 95%) and at 20°C. VOC emissions from these materials are analysed by GC-MS and HPLC-UV methods and linked to odour assessments. The fungal growth on the material and fungal spore emissions in the air are jointly evaluated (quantification and speciation). This way, the relationships between fungal growth, odour and VOC emissions are examined.