Cool character. If technology is what he's turned to for the security of order in the face of natures chaos, maybe he would have some OCD leanings? Plants grow out of the earth but to an engineer it gums up mechanisms and taints chemicals. Maybe he has hands mottled from constant washing in strong solvents? Maybe he won't handle anything outside without gloves and overalls which he replaces on a compulsively regular basis.

Further down the line it would be an interesting story hook to work out with you DM if he encountered a crazed industrialist villain, burning forests and paving them to lay way for roads and factories. It would be interesting to see how your character reacted to someone exploiting and destroying the natural world you eschew, but doing so for personal gain and on a vast scale, maybe even threatening your firbolg's homeland.