This is just a quick question, but I really wanted to get people's opinions.
What would you say is more cost effective (in terms of electricity bills), ceramic heat bulbs, or heat mats?
Heat rises...
Heat from a heat pad/heat mat will thus radiate upward when installed properly (under the tank/cage). Couple this with various substrates, aspen, repti-carpet, coconut fiber, even paper towels and you get an insulating layer that will aid in regulating temps. Not to mention, most heat pad/mats don't draw much wattage. Example, a 12x9 inch zoomed heatpad I use is listed to only draw 16W. the smallest size zoomed brand heatpad, which I also use only list drawing 4W.
Ceramic heat emitters get screwed into light fixtures, and are to be used in the heavier duty ceramic-base clamp/drop lamp fixtures vs using plastic-base fixtures. They are intended to sit atop a cage and radiate downward. Though they, and even basking bulbs, do radiate downward and heat the specific area, much of the heating energy is lost from it radiating upwards. This is part of the stupidly annoying and asinine, US congress-passed law that has done away with 40, 60, 75, and 100 watt bulbs, which is how I heat many of my non-snake cages. Ceramic heat emitters also come in much higher wattages than heat pad, which the lowest I've seen being 50W. That right there pretty much kills the argument of which is more cost effective.
The better question would be what's the most energy efficient (cost effective) thermostat? A simple rheostat, or on/off type thermostat is probably going to be the most ineffective at regulating electricity to the heatpad. These are designed to be either on (100% energy consumption) or off (0% consumption).
Proportional thermostats are probably the best option when it comes to regulating a heating device, be it a pad/mat or ceramic emitter. These types of thermostats are always on. HOWEVER, they are not always 100% on. When properly set up, they are designed to bring the heating device to the set temperature and then electrical current to the heating device is scaled back (proportioned) to maintain that set temp. In example, my custom incubator is heated with heavy-duty mental pipe tape (
http://www.heatersplus.com/hb.html) and controlled by a Spyder Robotics Herpstat ND proportional thermostat. I use two 20mm CPU fans to circulate air and an aquarium air pump to pump in fresh air. When I fire up the incubator for the season, once it has reached temp it will typically only need to draw a 10% load to maintain the set temp, thus avoiding temp spikes within the incubator. In contrast, a non-proportional thermostat would kick on at 100% power once the temp sensing probe triggers the units to come on and maintain temp.
TL;DR - A heatmat coupled with a proportional thermostat is going to be the most cost effective heating means.