A great, easy, and relatively cheap energy saver would be a second roof.
This is a roof built about 6-8"s above the current roof. The East/West facing sides would extend a little past the roof, and the North/South sides would be even with the current roof.
You put wire around the gap to keep critters out.
The way the second roof will reflect a lot of heat, and the heat it absorbs will be vented out the 8" high gap between roofs.
This could save a LOT of money on energy bills.