There is a huge misconception many people have about promoting the general Welfare. It's a phrase that basically means no crony capitalism (which in practice tends to appear even more with socialist politicians). The general welfare is the welfare of everyone in the country, as opposed to the specific welfare of individuals or a geographic or other subset. So defense spending defends everyone, but solar panel company loan guarantees benefit only the people who buy and sell solar panels, making it out of scope for Congress' power to raise and spend money.
In terms of Energy Star specifically, it's a completely useless rating which just encourages manufacturers to have their default "energy saving" rating take say, two hours to do a load of dishes (because then the energy consumption per minute is really low!) and when consumers complain, they add a speed wash mode you can select which uses way more energy but actually does the dishes in a reasonable time.