This study revisited the fundamentals of allocation to joint products and proposed new models for allocating common greenhouse gases emissions among coproducts of biorefineries. These emissions may account for more than 80% of the total emissions of greenhouse gases of the biorefineries. The proposed models optimize the reward of coproducts for their compliance to environmental requirements. They were illustrated by a case study of wheat straw biorefinery built on the literature. Several scenarios were considered with regard to the grain yield, field emissions of greenhouse gases, allocation between grain and straw and policy requirements. The results conform to the expectations and are sensitive to the policy targets and to the environmental performance of the counterpart system. Further research works are necessary to achieve a full application to complex processes. However, the proposed models are promising towards assessing the simultaneous compliance of coproducts of a biorefinery to environment policy requirements.