please try to find set of variables describing problem, maybe relation to the Sustainable Development Goals (established by United Nations) is the one of the possible approaches. Then you can analyse them qualitative and quantitative. The method is not so discussable as the choice of the factors and theory you want to base your research.
The most popular are: the theory of sustainable development, green (environment oriented) development, business ecosystem (determinants), and corporate social responsibility. Depending on the chosen theory, you will get different approach - direction of the analysis.
You can also ask general questions what is green for business? What is green innovation? Is green innovation related to the green business (sustainable organisation) etc.
Maybe some of my works, you can find helpful:
Conference Paper Eco-innovation as an Element of Business Value and Performan...
Conference Paper The Green Economy Development Factors
Conference Paper Green Entrepreneurship in the European Integration Context
First you have to decide what green innovation for tourism is and then try to develop quantitative and qualitative measurements as ratio’s. And keep measuring and improving them.