Do HP from green steel items stack

[Kyber.Coryn]

I have crafted a green steel helm which among other things gives me Improved Elemental Energy which is +15 hp. I have now crafted green stell goggles and i want to add some more hp. Will they stack?

[Shima-ra]

Different tiers will stack, but not the same tier with itself.
Elemental Energy
Improved Elemental Energy
Greater Elemental Energy

In other words, you can put +10hp and +20hp in your new item for a total of 45, just don't add that 15hp tier2 in it because it will be a waste.