By my reckoning...
Your bulb uses 100watt/hours per day (assuming 20w for 5 hours). That works out at 36.5kWh p/a.

Can't find hard stats for a freezer (greater variability), but one source quotes a nominal drain of 500w/hour. This is acknowledged to be misleading; as the machinery is thermostat controlled, it won't be running continuously, but with an estimated 10% duty cycling. That's 1,200 watt/hours per day, or 438kWh p/a; which is 12 times the drain of your energy saving bulb.

The numbers look even better when you factor in that Freezers with large air-voids are less efficient, and most low-power bulbs are rated less than 20w.

(edited for spelling and grammar)
(The Incredible Sulk Finally remembered his password on, Tue 3 Mar 2009, 18:03, Reply)