Concern for the health of the natural environment is growing as human population grows. Recently, renewed attention has been given to the environmental impact of fires and the fire implications of sustainability choices made in the built environment. To properly understand the environmental impact of fires, however, it is crucial that we can estimate fire emissions. This paper explores the concept of fire emissions and emission factors and investigates the potential to use small scale testing to develop emission factors for fire emissions. The findings show that there is a potential to use dynamic tests such as the cone calorimeter (CC, ISO 5660) and fire propagation apparatus (FPA, ISO 12136) to develop emission factors to estimate larger scale fire emissions, at least for CO and CO2 emissions. While there is a spread of data from between the CC or FPA and the medium scale tests, this is of the same order or less than the spread between the two small scale tests. The spread in emission factor values from the various tests is smaller for CO2 than for CO and greatest for small CO-emission factors (< 10 g/kg). More work is needed to similarly characterise a broad range of species.