Answer: Most evergreens are very large and ultimately broad trees, so you are right to be concerned about the space. In order to get the height you want without taking up too much "floor space" you will need to look at trees with an upright pyramidal or columnar form. Several junipers meet that requirement and will do well in a full sun location and also grow relatively quickly, expecially when compared to most dwarf conifers. You might consider "Witchita Blue" or "Skyrocket". You might also consider an upright and relatively narrow form of arborvitae (Thuja occidentalis) which should also do well for you.
Q&A Library Searching Tips