Al, to add to what Boyd said, though I suspect you already either know or could figure it out...
First, sort of an aside: we have two HVAC systems in our house, as we can easily shut down half of it for most of the winter. I've found in two different type of houses we've had, one a two story, one a long, long single story, that it pays to have two HVAC systems. This is primarily a decision about comfort; as you older folk know, it wasn't unusual to have a two-story house with only bedrooms upstairs, and they didn't need to be heated at all. But once you make the decision to have heat/cooling in a whole house of a significant size, multiple systems often make the most sense.
The other thing about our current house is we are outside the natural gas delivery range, so "gas" means "propane." Since 2002 or so, propane costs rival & sometimes exceed the cost of of gasoline. On the other hand, electricity here is relatively cheap. Finally, we've also found that electrical power here can be disrupted, usually by storms, and leave us without power, typically for a week. Historically, this happens about once every 3-4 years.
So in our case, when propane skyrocketed, the decision to switch to electric power also meant considering the cost of an auxiliary generator. And if the only heat source we had was electric, that would have meant a huge generator.
The final decision was to use "electricity only" in the portion of the house we could shut down, and a dual-fuel heat pump on the half of the house we live in all year. Next, we set the transfer temperature lower than recommended. As Boyd said, operating a heat pump outside a certain range is less efficient. Just generally, more than a 30-degree change in temperature is one issue, the other is that as the temperature drops, you have to use some of a heat pump's heating to keep it's own coils from freezing.
But one thing people don't usually know is that you can still run a heat pump outside it's optimum region. It works much harder, and the discharge temperature is lower, but it works. And if you set the transfer point lower, you can always manually override to "emergency heat" & kick in the gas furnace. Changing the setting of the transfer point though, seems to be a "service call" kind of issue, rather than a user "manual override." You wouldn't want to do this with natural gas at it's current price. Propane is a different matter entirely.
OK, I've gone on a lot because that's my nature, but also to try & make the point that where you live, what your house is like, and what's you're willing to accept are all factors in any HVAC system. But they're usually sold, even at the local dealer/installer level, as one size fits all. More than marketing -- the engineers you hire don't really have much experience with all the possibilities, so they go with what their willing to stake their professional reputations on, and that's a fairly narrow range of options, because historically, we've used a fairly narrow range.
Another BTW that Boyd touched on -- humidity -- water -- can also be a largish factor. Decisions that make sense one place won't work in others. I looked at a half-underground house, but had to abandon the notion because in the south generally, and where we live particularly, controlling the water content of the living space would have gotten very complicated.
* * *
This thread started out as one looking answers on a global policy basis. I think that's futile. But we can all make better decision on an individual -- local -- level. How big a factor you want "cost" and "green" to be is suddenly manageable. The hard part is finding the knowledge from experienced people, because this is a relatively new notion.
(I don't man you can't find experts on alternative systems. But what I've found is we're in such early days they each view their particular alternative system as the answer, and so, continue to overlook individual needs & wishes. What is harder to find is the expertise that can come up with the best system for an individual. Since it's rare, it costs, too.)
First, sort of an aside: we have two HVAC systems in our house, as we can easily shut down half of it for most of the winter. I've found in two different type of houses we've had, one a two story, one a long, long single story, that it pays to have two HVAC systems. This is primarily a decision about comfort; as you older folk know, it wasn't unusual to have a two-story house with only bedrooms upstairs, and they didn't need to be heated at all. But once you make the decision to have heat/cooling in a whole house of a significant size, multiple systems often make the most sense.
The other thing about our current house is we are outside the natural gas delivery range, so "gas" means "propane." Since 2002 or so, propane costs rival & sometimes exceed the cost of of gasoline. On the other hand, electricity here is relatively cheap. Finally, we've also found that electrical power here can be disrupted, usually by storms, and leave us without power, typically for a week. Historically, this happens about once every 3-4 years.
So in our case, when propane skyrocketed, the decision to switch to electric power also meant considering the cost of an auxiliary generator. And if the only heat source we had was electric, that would have meant a huge generator.
The final decision was to use "electricity only" in the portion of the house we could shut down, and a dual-fuel heat pump on the half of the house we live in all year. Next, we set the transfer temperature lower than recommended. As Boyd said, operating a heat pump outside a certain range is less efficient. Just generally, more than a 30-degree change in temperature is one issue, the other is that as the temperature drops, you have to use some of a heat pump's heating to keep it's own coils from freezing.
But one thing people don't usually know is that you can still run a heat pump outside it's optimum region. It works much harder, and the discharge temperature is lower, but it works. And if you set the transfer point lower, you can always manually override to "emergency heat" & kick in the gas furnace. Changing the setting of the transfer point though, seems to be a "service call" kind of issue, rather than a user "manual override." You wouldn't want to do this with natural gas at it's current price. Propane is a different matter entirely.
OK, I've gone on a lot because that's my nature, but also to try & make the point that where you live, what your house is like, and what's you're willing to accept are all factors in any HVAC system. But they're usually sold, even at the local dealer/installer level, as one size fits all. More than marketing -- the engineers you hire don't really have much experience with all the possibilities, so they go with what their willing to stake their professional reputations on, and that's a fairly narrow range of options, because historically, we've used a fairly narrow range.
Another BTW that Boyd touched on -- humidity -- water -- can also be a largish factor. Decisions that make sense one place won't work in others. I looked at a half-underground house, but had to abandon the notion because in the south generally, and where we live particularly, controlling the water content of the living space would have gotten very complicated.
* * *
This thread started out as one looking answers on a global policy basis. I think that's futile. But we can all make better decision on an individual -- local -- level. How big a factor you want "cost" and "green" to be is suddenly manageable. The hard part is finding the knowledge from experienced people, because this is a relatively new notion.
(I don't man you can't find experts on alternative systems. But what I've found is we're in such early days they each view their particular alternative system as the answer, and so, continue to overlook individual needs & wishes. What is harder to find is the expertise that can come up with the best system for an individual. Since it's rare, it costs, too.)
, but are still pretty cool, in the nerd sense of the word. It is about time they started a competition in which the rules include two passengers, carrying cargo, safety equipment, etc., like a normal car. Then we would see the type of car you have been waiting for.