If you heat with electricity and live in a warm and sunny climate, consider installing a solar water heater. The solar units are environmentally friendly and can now be installed on your roof to blend with the architecture of your house.
To store project plans, reference materials and magazine clippings, keep at least one two-drawer file cabinet in your workshop. You may be able to tuck them under existing workbenches. Or, if you will be building new workbenches, design them to accommodate the file-drawer cabinets.