It makes a difference to the planet how you store your samples!
So how should you store your samples? Well, of course that depends on the content of the sample and the time you want to keep it!
Ask yourself these questions every time you are about to store a sample:
Does the sample need freezing? In that case: ultra-low or -20°C? Would a fridge be sufficient? Or maybe even room temperature?
It might seem insignificant, but correct storage of your samples can potentially reduce energy consumption drastically!
It takes energy to cool down your sample, and more importantly: the temperature increases every time you open the door of a freezer or a fridge -- and that´s bad news for the planet.
Going from -68°C to -70°C takes much more energy for a freezer than going from -18°C to -20°C.
So don´t go for the lowest temperature simply because you can.
Go for the right one!