Testing is inexpensive, and is done with portable X-Ray Fluorescence machines (we use the Thermo Niton units).

Check used building supply stores to replace the fluorescent lights in both rooms though.

I just saw that there are now (pricey) LED replacements for those long fluorescent tubes.

These offer much more positive control than a conventional thermostat in a lockbox in the hallway.For electrical, the obvious...switch to cfl's or T8 fluorescents with electronic ballast; High pressure sodium or other efficient exterior lights that should be on dusk to dawn sensors only.

There are some requests (or demands) that are reasonable ("Could you install a fluorescent fixture with a pull chain above the basement laundry?"

The driver, similar to a fluorescent ballast, will burn out quickly if it doesn't receive the proper voltage.

If there is a laundry area, I had one tenant once request a fluorescent fixture over the laundry area; that was inexpensive to do, with a pull-chain switched fixture.

If you want to replace a regular one then just remove the old/regular one and install the new dimmer one.Nut remember that you can't use a dimmer switch with fluorescent bulbs, they only work with some LED bulbs and incandescent.  

If the lamps are already LED or compact fluorescent, this won't help much.One thing you might ask the electrician to check is if any of the outlets are "back-stabbed", "stabbed", or "back-wired". 

Was it an led, fluorescent, or old fashioned 100w incandescent?