Insulation performance is measured in 'R values', – 'thermal Resistance'. The thermal performance of equal R value rated products is the same. Eg R2.6 Terra Lana has the same thermal resistance as R2.6 Fibreglass. However, thermal resistance is not all there is to insulation performance – Terra Lana wool blend insulation has been independently tested to show that it interacts with changing moisture levels enabling it to act like a thermal mass.
For further advantages and more comprehensive explanations of the above, go to 'Why Wool'.