This means that the primary space can be: 1) controlled and conditioned by a small amount of purchased energy, which is low-in-cost and environmentally friendly, or, 2) the primary space can be controlled and conditioned by active renewable energy, like solar thermal energy, which is completely pollution free. All Enertia® homes are initially designed for this renewable energy boost to be added in the future, using the envelope/buffer zone as an access channel for the upgrade.

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