It's common for needles get a lighter shade in winter, I find a newly planted evergreen is normally a bit in stress the first two years also and that doesn't help the situation.
What might can help,..see if you can get some water soluble high acid fertilizer and spray the whole tree with a watering can one's a week for about 6 weeks in the growing season.

I have experimented with miracid from miracle grow, not sure if still available, when I grew thousands of spruce trees from seeds and other evergreens, nothing could kill them, even when about 3 times the strengths used,..the more the merrier it seemed, they just loved it.

All evergreens love high acid fertilizer, our ground is normally high in alkaline. I only given them the first 3 years or so when planted, after that they do fine without.

Hi konrad, thank you so much for your help! This is very reassuring indeed. I will go and find some acidic fertilizer now. Hopefully that will help! Thanks so much.