Well, we're not interested in a thermodynamic comparison. We're interested in a useful-energy-obtained for useful-energy-spent comparison. For instance, if I leave a block in the sun and then bring it inside, I have only expended the energy to move the block out and then move the block in. It doesn't make sense for me to include the sun's contribution to the system because that's not a cost I incur.
The actual apples to apples comparison in efficiency _is_ the heat emitted by the block in my house divided by the cost of moving the block.
The actual apples to apples comparison in efficiency _is_ the heat emitted by the block in my house divided by the cost of moving the block.