Q.boxwoods and junipers
We have both of these bushes and the tips of both are turning brown and yellow on various parts of the bushes. What could be causing this?

There can be a few reasons for these issues with your shrubs, including environmental, pests and disease.
These links will help you determine the cause.
https://www.gardeningknowhow.com/ornamental/shrubs/boxwood/yellow-or-brown-boxwoods.htm
http://www.clemson.edu/extension/hgic/pests/plant_pests/shrubs/hgic2056.html