About 25 years ago I purchased an auto repair facility out of bankruptcy court that had an environmental problem.  

This will reduce your footprint and units.  .5 acres is a really small footprint. 

Landscaping has the largest ROI (of about 200%), adding a wood deck or a patio will also provide a big increase in value (100% ROI).Add living space, consider converting attic space, finishing a basement, or repurposing a large living area to add a bedroom without expanding the home's footprint - this will give you an average ROI of around 75%.

Bought an auto repair shop for 30% of value because of environmental problem.  

But I'd be careful with any long term forecasts (economically, demographically, environmentally, etc.).

The easiest way to ask a buyer is to visit large footprint new home builders model homes.  

Chances are you don't want to buy a building that had PERC spills and EPA just chomping at the bit to hit the new owner with environmental cleanup costs, that might be way more than the building is worth. 

If the plan is to alter the footprint of the home your site plan will need 2' elevation contours, trees and waterways marked.

I just don't have the patience to wait four years and spend 6-figures for environmental studies on a 1-MW, four-acre project.

Or figure out how projects are developed and get one "most of the way" (land leased, site planned, permitted, power purchase agreement signed) and then sell the deal to a big developer.My perspective: My W2 for the last 8 years is environmental and development consulting for oil & gas, renewables generation, transmission, and commercial RE development.