I have a 10x10 office and a 30x24 conference room with 10' drywalled ceilings. They want to light it up with these http://www.iuseelite.com/product.asp?aid=6FLOURE&pid=B62PLIC&pt=FLOURE001. I am assuming 50 to 60 footcandles would do the job. Any ideas on number of fixtures and spacing