Affordable sturdy windows for workshop

We don’t do laundry there; it’s only used as a storage room. The room has no heating and can freeze in winter, so it’s not suitable for the good new washing machine. I basically accepted the windows by silence as approval, I didn’t know how they were supposed to be installed and assumed that a professional company would do it correctly. I’m not a construction expert and we had no money for construction supervision. We initially got a quote and quickly dropped it again. It would have cost at least 10k euros, and then a significant part of our 60k euro budget would have been gone without a single stroke of work having been done. We would never have managed the conversion to an energy-efficient house that way, which in any case was only achieved with considerable personal effort. Unfortunately, we are not high earners but live on a small salary from which everything has to be paid.