I was an early adopter (2005) of a solar panel for domestic hot water. I think this has probably been a Good Thing, but it is, for obvious reasons, hit-and-miss and it pretty well useless between early November and early February. It still works and is genuinely zero-emissions now it's fitted as the pump is driven by 12 solar-powered volts. It does require that the water be softened in the summer, which almost certainly counts against me. I have never looked up how much CO2 is emitted by the production of softener salt.
I bought a Vauxhall Astra with an LPG conversion, which I believe is marginally less harmful than petrol, but the main reason for this was economics. I calculate that it saved me about £1000 a year in fuel. In the 3 years that I had it I drove about 75000 miles.
I was an early adopter of an electric car - a Prius in the first instance, which was by far the most economical petrol car I've driven. Eventually the battery conked out and from being a >60 mpg car, it came down to about 45 mpg. We were at that time driving so few miles that it wasn't worth changing (about 4000 a year shared by 3 drivers). I was doing almost twice that on my bike. for a while. That was replaced by a 24kWh Leaf. We still drive an EV and I will never go back. They are just vastly superior.
Had the house double-glazed (2001) and, in recent years, have had several rooms decorated and insulated.
I have only ever flown for holidays on 3 occasions that I recall, the earliest in 1964, the most recent in 2005.
Last year we switched from gas cooking to an induction hob. I think that must make some difference, especially since, for 6 years now, we have used Ecotricity as an electricity supplier. We still have gas central heating and I don't anticipate changing that soon.
We have cut down on our meat consumption and I have always thought about "air miles" when it comes to buying fruit and veg - but that isn't always a great guide. It is probably less damaging to buy grapes from Egypt, say, than it is raspberries from Kent in October.
We have done lots of cycling, but I have to say that since the reduction in return that has come from having an electric car, both in terms of money and CO2, I'm a bit less inclined to stagger back from the stupormarket on a bike laden with about 30kg of stuff.
I have done quite a lot of train travel, including trips from Southend to San Sebastian, Southend to St. Andrews and Southend to Salzburg. My holiday destinations do not always begin with an S.