Design a company logo and a logo for a certificate

We are looking for a Logo design. It is for a company that certifies CO2-Efficiency. The Logo should be as clear and as minimalistic as possible. The name of the company is "CO2-Score". The logo for the certificate should consist of the company logo and some form of representation of the individual scoring. (The certified products will receive a score. This score is than printed in form of the certificate onto the product. The score ist represented on the product in one of five categories (excelent, above average, average, below average, far below average). The representation of those categories can also be on a scale, it can be with symbols, numerically, or however you see it fit.) The important things are: 1. It has to be very easy to understand (imagine a product in the supermarket, with our certificate - the consumer should be able to understand the certificate, even if they do not know the concept of the certificate). 2. The design should also work in two colours (but the design can have more colours - this is just necessary in cases where the client does only want two colours). I hope that this explanation clarifies the essentials. Thank you for your consideration