What we're trying to do is to take a life-cycle assessment of both the cost and the environmental impacts of anything we buy. For example, there is a certain cost to buying something, and then it will last a certain period of time. If you buy something, and it lasts 10 years, you may think about buying something better, which might be a little bit more expensive but lasts for 15 years, so you could do a cost assessment of that. You also want to look at the environmental impacts of those things.
You want to have a mix of best value, which includes the environmental impacts of that over the life cycle of a product, versus the cost of that product.