There are a few things that can cause damage such as this to a dwarf Alberta spruce. Spruce spider mites cause areas to first brown and then die. The problem often spreads and can kill a plant. Secondly, winter damage from wind or salt exposure can make a DAS bare on one side as well. Thirdly, any plant that might have been hit with herbicide, salt, household cleaning products, hot water from a sun heated hose etc will experience dieback.
Our best guess for your plant is spruce spider mites. There is a way to see if there are mites: put a piece of clean white paper under a branch or two, then shake the tree/branch. Little moving dots are red spider mites.If uncertain, crush and smear the dots. Mites will produce a brown streak when smashed.
In our region, our hot, dry summers make these shrubs very vulnerable to attack from the mites. Unfortunately these plants don’t regrow from bare wood, ever. So those parts of the plant that are dead now will always be dead, and the green growth on this plant doesn’t look too healthy either.
Hose the plants down thoroughly, with a forceful blast of water from the hose, and make sure they are well watered -not soggy- but that the soil is wet down to at least 6 inches or more. We like to build a little “moat” z(about 3-4 inches deep) around shrubs, out at the drip line, where the ends of the branches reach. Fill that up with water and let it disappear a couple times. In a few more days, repeat the hose blast, and fill up the moat again.
See if this helps at all. The cooler weather is on its way.
Let us know if this helps.