A neighbor just told me that my siding should have small vent holes in the under side of it to let heat out instead of it moving into the house. Is there any truth to this? I've never heard this before.
Thanks.

Are you talking about vents in the soffits?

Harold's question will lead you back to the neighbor to set him staright. No vents in siding but aluminim vents are common in the soffit. http://www.ventmasters.biz/Roof,%20S...le%20Vents.htm