Hello. You have not shown the neighborhoods to which the question relates, which makes it impossible for your question to be answered accurately. However, I will try to help you in the best possible way.
The best way to reduce spending on carbon dioxide and increase biodiversity in a neighborhood is to provide tree planting through urban afforestation. A well-wooded neighborhood, it has a lower concentration of carbon dioxide because the plants absorb this gas releasing oxygen in place. In addition, some animals such as birds would attract them, in addition to promoting fruit and shade for the neighborhood.