[SigmundA]

In the case of geothermal heat pumps they work well regardless of outside temperature and are even more efficient at both heating and cooling.

The nice thing about cooling, its greatest demand typically coincides with the best time to collect solar energy. Solar is perfect for offsetting the a/c, they are a great combo in sunny warm climates.

[Xarodon]

Ground source heat pumps, AKA what most people call 'geothermal', have their own inefficiencies.

In the winter, when you're using it to heat, it collects heat underground and brings it up to be concentrated and released into your house, this concentration costs energy. Though in the grand scheme of heating your house, any heat generated inside your house isn't a loss. Due to the fact you have to have buried pipe which you pump liquids through, you'll lose some efficiency to head loss and gravity. Those loses happen outside your house too.

Ground source heating is a lot more economical as it uses far less electricity than resistance heating for the same BTU output (because it's "stealing" heat from somewhere else), but it's not more efficient. But if you ask anyone who has to heat their house in the winter, electric heat is the most expensive. It may be efficient, but electricity isn't cheap.

As for cooling, Ground Source Cooling would be more efficient than a conventional AC (as it's not compressing and then evaporating a refrigerant on a coil).

The nice thing about cooling, its greatest demand typically coincides with the best time to collect solar energy. Solar is perfect for offsetting the a/c, they are a great combo in sunny warm climates.

I hadn't ever thought about the double effect of solar panels on your roof protecting your house from heating up by absorbing the sun, and then using that power to cool your house further. That synergy makes me smile.

[SigmundA]

You seem to be implying its not more efficient on a technical level because its "stealing" heat while a heat strip is just converting electricity to heat with no loss. But that doesn't matter its free heat in the environment. Heat pumps are literally over unity and have over 100% efficiency, but its usually specified as their coefficient of performance which is a number usually 3-5, meaning they move 3-5 times as much energy as put into the system.

Bottom line 1500w heater puts 1500w into the room 100% efficient, a 1500w heat pump will put 4500w or more into the room 300% efficient or more, they both use the same amount of electricity.

[sbradford26]

Geothermal definitely helps overall efficiency. Sadly the upfront cost is still pretty high.

Also solar helps in other ways because it makes it so less heat is absorbed into the roof of the house.

[SigmundA]

Geothermal is not only more efficient its actually viable in below freezing weather. Air source heat pumps outside coils will freeze up with ice once the temperature goes low enough causing them to stop functioning.

The ground temperature 30 feet down is basically stable year round and well above freezing just about anywhere on earth. This allows them to function even mid winter in cold climates while air source heat pumps much switch over to more conventional heating.