Most listings are in the $30's per square foot per year. The Loudoun County region is going through a a rise in rates. In the last 3 months, the median rate increased $7 per sqft per year. That's a 28% increase in rent.
In the last 90 days, 34 listings have been made available, which means leases might be going fast. You'll want to be prepared to make an offer immediately. About 3% of the listings in the Loudoun County are subleases, so you will probably need to consider the implications of signing a direct lease with the building. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
Even though the median size is 3,980 sqft, there are still 0 listings below 2,000 sqft. Most buildings in this market are approximately 1 floors. Most buildings in this area were built in 2000 and are Class A.