The whole thing sounds like late-stage capitalist hogwash. This all seems very inconsequential except to make a bunch of rich people richer.
If you lower the energy demand on the grid then you lower the price that the grid needs to pay by a lot.
Grids tend to take in bids from power companies of Volume + Price and then pick enough Volume (at the lowest Price first) until they get to the expected Volume and then payout to those winning bidders the Price of the last needed Volume. If you can decrease the Volume then the total price paid by the grid goes down.
If sharing some of that energy savings with another entity it's still a win-win because you're overall paying less.
It's like hiring a tax account where they get paid 50% of whatever taxes they save you. It's a win-win until they start committing tax fraud.
The energy savings were sold by HD twice - once to the customer (who pays a premium for less energy usage, and may also have claimed federal tax credits), and once more to America Efficient (who sold them to the state / grid operator non-profits).
It's an interesting kind of subsidy arbitrage - since businesses can benefit from subsidies that consumers cannot, it creates an incentive to carve out the subsidy-granting-essence from consumers sales and sell them on in aggregate.