A durable building provides a long period of time to amortize the environmental costs that were incurred in building it. If you double the life of a building, you halve the environmental impacts of its creation. But a durable building is only as good as its parts. Using long-lifespan products and materials means they will not need to be replaced or repaired as frequently, so the raw materials, energy, and environmental impacts invested in them can be spread out over more time. An additional durability issue at Mariposa Meadows is the ability to test products and building systems at high altitude to see how they endure.