Ask HN: How to compute 'byte miles' and other Internet traffic costs?

Can anyone help me make better estimates for the 'costs' of serving pages over HTTP/2 vs HTTP/1.1 for this item that I'm working on? http://www.earth.org.uk/note-on-carbon-cost-of-CDN.html At the moment I'm seeing a 10--100% inflation in visible bytes on the connection for my simple case, but I'm not including factors for distance travelled, crypto overhead, TCP setup costs end-to-end for 'extra' connections, per-packet costs, etc! All help gratefully received!