What is the average energy efficiency (in percentage) of the following appliances:
1) Ceiling Fan (rating: 50W)
2) Air Conditioner (rating: 3.5KW)
3) Refrigerator (rating: 500W)
4) Washing Machine (rating: 500W)

Is sufficient energy wasted as heat (from these appliances) so as to convert it into useful energy?

Can you suggest a few ideas of using this heat energy produced??

Have you tried the following searches? You might find something that will be helpful to you on them.

Appliance Efficiency Ratings - Google Search (http://www.google.com/search?hl=en&safe=off&q=Appliance+Efficiency+Ratings)

Appliance Energy Lost and Used - Google Search (http://www.google.com/search?hl=en&safe=off&q=Appliance+Energy+Lost+and+Used)

Harnessing any of the heat produced by those devices would be, I think, very difficult if not impossible.

Is there a particular reason that you are asking this question? Knowing as to why you are asking the question would probably help to help you the best here.

Thanks!