I have been wondering recently whether having my groceries delivered is a net ecological benefit or not.
It is highly likely that the overall environmental impact of the diesel used to delivery my groceries, when amortised over all of the deliveries, would be less than the impact of my own individual petrol journey to and from the supermarket. However, how do I take into account the fact that when the supermarket delivers it uses plastic bags, whereas if I were going there myself I would be using reusable bags.
It is not obvious to me what the relative environmental impact of these two factors are, or how I can make a sustainable decision.
The only option that I can see which would be win-win would be to take public transport to the supermarket and use my reusable bags. That way both my travel and materials footprints would be reduced. Alas there is no convenient public transport available, which leaves me in my present dilemma.
So, how can I easily calculate if it is more sustainable to have my groceries delivered using plastic bags, or drive to buy them myself and use reusable bags?