The answer is obviously "no" since there are other parts of the world that don't live on a hurricane highway nor build houses made from firewood in an area prone to wildfires.
Perhaps what should be more commonly accepted is that the US is a land of great natural beauty! And large tracts of it should be left to nature.
What's the average monthly leccy bill in Phoenix during the summer? $400?
Where does LA get most of its water? Local sources? I don't think that's the case.
New Orleans is a future Atlantis.
San Francisco is a city built by Monty Python. Don't build it there it'll fall down, but I built it anyway, and it fell down, so I built it again...
The average high temperature in Phoenix in July is 106.5F (41.4C). If you are cooling to 70.0F (21.1C), that's a difference of 36.5F (20.3C).
The average January low in Berlin is 28.0F (-2.2C). If you are heating to 65.0F (18.3C), that's a difference of 37.0F (20.5C).
I feel like many people living in climates that don't require air conditioning have this view that it's fantastically inefficient and wasteful. Depending on how you are heating (e.g. if you are using a gas boiler), cooling can be significantly more efficient per degree of difference. Especially if you don't have to dehumidify the air, as in Phoenix.
So every human in your cold space is 80W fewer watts of energy you need to produce to heat the space. But in a hot space, it’s an extra 80W that needs to be removed.
Add to that all of the appliances in a home. It’s not unusual for a home to be drawing 100W of electricity just keep stuff powered on in standby, and that’s another 100W of “free” heating. All of this is before we get to big ticket items, like hobs, ovens, water heaters etc.
So cooling a living space is always more costly than heating a living space. Simply because all the waste energy created by people living in the space reduces the total heating requirement of the space, but equally increases the cooling requirement of that same space.
All of this is ignoring the fact that it’s easy to create a tiny personal heated environment around an individual (it’s called a woolly jumper). But practically impossible to create a cool individual environment around a person. So in cold spaces you don’t have to heat everything up to same temperature for the space to be perfectly liveable, but when cooling a space, you have to cool everything, regardless of if it’ll impact the comfort of the occupants.
https://weatherspark.com/y/75981/Average-Weather-in-Berlin-G...
https://weatherspark.com/y/2460/Average-Weather-in-Phoenix-A...
This is your most accurate/relevant point:
> All of this is ignoring the fact that it’s easy to create a tiny personal heated environment around an individual (it’s called a woolly jumper).
Whereas this is plainly wrong:
> It’s much easier, and consumes less additional energy, to heat an occupied space, than to cool it.
And then the following is correct but the marginal reduction in load is minimal except in relatively crowded spaces (or spaces with very high equipment power densities):
> Thanks to the fact that your average human produces 80W of heat just to stay alive.
The truth is it is generally easier to cool not heat when you take into account the necessary energy input to achieve the desired action on the psychrometric chart, assuming by “ease” you mean energy (or emissions) used, given that you are operating over a large volume of air - which does align with your point about the jumper to be fair!
Generally speaking, an A/C uses approx. 1 unit of electricity for every 3 units of cooling that it produces since it uses heat transfer rather than heat generation (simplified ELI5). It is only spending energy to move heat, not make it. On the other hand, a boiler or furnace or resistance heat system generally uses around 1 unit of input energy for every 0.8-0.9 units of heating energy produced. Heat pumps achieve similar to coefficients of performance as A/Cs, because they are effectively just A/Cs operating in reverse.
Your point about a jumper is great, but there are local cooling strategies as well (tho not as effective), eg using a fan or an adiabatic cooling device (eg a mister in a hot dry climate).
> So cooling a living space is always more costly than heating a living space.
Once you move to cost, it now also depends on your fuel prices, not just your demand and system type. For instance, in America, nat gas is so cheap, that even with its inefficiencies relative to a heat pump, if electricity is expensive heating might still be cheaper than cooling per unit of thermal demand (this is true for instance in MA, since electricity is often 3x the price of NG). On the other hand, if elec is less than 3x the cost of nat gas, then cooling is probably cheaper than heating per unit of demand, assuming you use natural gas for your heating system.
I thought any place that is significantly cold can still dig underground and at some point you can get enough heat to run your heat pump?
This simply is not true for a furnace or electric resistive heat.
My furnace produces 0.9W of heat for every 1W of energy input. More efficient ones do 0.98, the best you get with electric resistive heat is 1W.
On the other hand my air conditioner moves 3.5W of heat outside for every 1W of energy input.
* In cold weather, solar heat gain can work in your favor as well. Much of the effect will depend on the orientation, shading, and properties of your windows, though. On the other hand, as another commenter pointed out, more sun in southern, cooling-dominated climate can also mean more, cheaper electricity.
* If you have a heat pump water heater, it will actually _cool_ your space significantly. The heat is transferred from your home to your water and mostly goes down the drain with it.
* At 65F (18.3C), most people I know would already be wearing a jumper/sweater. That's why I chose a lower target temperature for Berlin. The best source I could find[1] indicates that in November-December of 2022 (in the context of rising energy prices due to Russia's war with Ukraine), Germans actually kept their houses at 19.4C, on average.
* Maybe I'm moving the goalposts a bit, but I chose Berlin mostly because the numbers worked out conveniently. As someone who grew up in the American upper midwest, I wouldn't consider Berlin to be particularly cold. Phoenix, on the other hand, is the hottest city in the country and its summers are some of the hottest in the world. In general, the hottest cities are still closer to what we'd consider room temperature than the coldest are.
[1] https://www.cleanenergywire.org/news/80-percent-german-house... (original report is on German)
So you are spot on, in winter temperature deltas are larger, and efficiency goes up.
https://backend.daikincomfort.com/docs/default-source/produc...
For each day, use the average high and the average low. Subtract the desired maximum dwelling temperature from the average high: if the result is positive, add it to the cooling degree-days total. Subtract the average low from the from the minimum dwelling temperature: if the result is positive, add it to the heating degree-days total.
Over a year, that gives you comparable figures on how much you will need to cool or heat the space. Many agencies calculate this for specific areas.
Here, for example, are the current season numbers for Boston: https://www.massenergymarketers.org/resources/degree-days/bo...
Generic regional numbers for the US: https://www.eia.gov/energyexplained/units-and-calculators/de...
There are multiple relevant temperatures for a heat pump, and the pump is more efficient when some of those are higher and some lower. A heat pump has two heat exchangers, one on the inside of the building and one outside. Each of those heat exchangers has two temperatures: the refrigerant loop temperature at that point, and the ambient temperature (air for air source heat pumps, ground for ground source heat pumps). There's also a fifth relevant temperature that has indirect influence: the setpoint (the desired indoor ambient temperature).
Efficiency increases when the temperature delta between the refrigerant and ambient temperatures is higher (both indoor and outdoor). But those temperature deltas vary inversely with the delta between the indoor and outdoor ambient temperatures.
So, in summary:
- Heat pumps get less efficient when the temperature delta between indoor and outdoor temperature is higher.
- They get more efficient when the temperature delta between refrigerant and ambient temperature is higher.
The net effect of this is that heat pumps become less efficient as the temperature becomes hotter outside in the summer and colder outside in the winter.
> plural in form but singular or plural in construction
(https://www.merriam-webster.com/dictionary/thermodynamics)
I think American and British English treat words like this differently.
On the other hand, depending on the humidity, heats over like 85F start becoming a health risk for some activities.
Nope. That's precisely wrong. Tl;dr heating normally uses less efficient technology than cooling and has to work across a higher temperature difference.
In Alberta or Minnesota, where the delta in the winter can be as high as 60 degrees centigrade (-40 outside, +20 inside) but only 20 degrees centigrade at most in the summer (+45 outside, +25 inside), heating is far more costly. Even accounting for waste heat from appliances. Most heating is done with furnaces, not heat pumps. Air conditioners are heat pumps and are 3x as efficient as a furnace. There are also less energy intensive cooling methods - shading, fans, swamp coolers - commonly used in the developing world and continental Europe.
On the other hand in a place with warm winters and hot summers, such as south east Asia, obviously cooling is more expensive because heating is unnecessary.
The highest temperature ever recorded is around 60 degrees centrigrade, a mere 23 degrees above the human body. The low temperature record is like -90, 127 degrees below body temperature. Needing to heat large deltas is way more common than needing to cool high deltas. And cooling is done with heat pumps, which are more efficient than the technologies used most commonly for heating (resistive or combustion).
> when cooling a space, you have to cool everything, regardless of if it’ll impact the comfort of the occupants.
Keep the house at 25 degrees centigrade and run a ceiling fan. 23 if you're a multi-millionaire. You'll be far more comfortable outdoors if your house is closer to the outside temperature. The North American need to have sub-arctic temperatures in every air conditioned space in the summertime is bizarre (don't even get me started on ice water).
You can also think about it as far as actually moving heat. Cold is the absence of heat, and so when the air is colder, there is less heat moved for the same effort and you have to work harder -- less efficiently -- for the same amount of head to get moved.
Some people on reddit are reporting quotes of 125k for larger (>3000 sq ft) houses.
As someone who lives in a 4-season environment that can get down into the single digits F on occasion in the winter (forecast to be there for a couple of days next week), and has an air-source heat pump, I just suck it up and eat the $400-$500/month heating costs for the auxiliary (electric resistive) heat in Dec/Jan/Feb. If someone gifts me a ground-sourced heat pump I'll gladly accept, but I've got kids to raise so setting aside money for one is a long way off.
Also in sunny climates it's easy to use solar energy for cooling making it carbon net-zero. Cold places typically burn natural gas for heating, it's much harder to make heating carbon net-zero.
A living space will naturally heat itself with zero furnaces or electric heaters. Because the living things inside it will always produce heat (at least until they cease to be living). On the other hand, you’ll have a hard time getting living things to cool any space they occupy.
> On the other hand my air conditioner moves 3.5W of heat outside for every 1W of energy input.
Heat pumps work both ways, and it’s still easier to heat a space with a heat pump than cool it. Sure your AC can move 3.5W of heat for 1W of energy input. But that means 1W of energy allows you to remove 3.5W of heat from a space. But if you used the heat pump to heat the space, you would get 4.5W of additional heat, because that 1W of energy used to power the heat pump becomes waste heat that can be trivially captured and used to heat the space.
In a cooling scenario, all waste heat is just that, waste. But in a heating scenario, waste heat isn’t waste, it’s additional heat you can use, and reduces the total amount of energy you need to inject into the system.
> Generally speaking, an A/C uses approx. 1 unit of electricity for every 3 units of cooling that it produces since it uses heat transfer rather than heat generation
You know you can use a heatpump to heat a space as well right? Then you get to move 3 units of heat into the space, plus you also get to use that extra unit energy used to power the heatpump, because the heatpump turns the unit of energy into waste heat! (After all energy can’t be destroyed, so it has to go somewhere).
In a cold environment, you can just take that energy from outside. If you’ve got a heatpump, then you can always set it up make sure that waste heat produced can be used to heat a space, and make sure that it’s always scavenging energy from a place you either want to keep cool, or from outside.
> Phoenix, on the other hand, is the hottest city in the country and its summers are some of the hottest in the world. In general, the hottest cities are still closer to what we'd consider room temperature than the coldest are.
If we’re talking survivable environments here, then phoenix isn’t a good choice. Places like Delhi are better where not only are the temps high, but so is the humidity. At times hot enough and humidity enough that the wet bulb temperature rises higher than human survivable conditions, in which case, without heat pumps, it’s literally impossible for humans to survive more than a few hours.
https://www.independent.co.uk/climate-change/news/wet-bulb-t...
That’s moving the goal posts. You can always use a heatpump to heat a space.
Any space you want to keep comfortable will always be easier if the outside is cooler than your target temperature. Everything in that space is going to produce heat as a natural consequence of expending energy into any form. It’s always possible to add insulation to minimise the amount of energy you loose into the surrounding environment, and you can always modulate how much additional energy you let escape using a simple opening in that insulation.
On the other hand, if the external space is hotter, then you must always expend additional energy to move waste heat energy accumulating in the space into the high energy space outside. There is no passive manner that can allow you to cool a space surrounded by a hotter space, you’re always fighting against the temperature gradient. And if you want your living, heat producing, organisms to keep living, then you need to get rid of the heat they produce.
Insulation obviously also helps keep a place cool. But no amount of insulation will ever remove the need for cooling if the outside is warmer than the inside. Energy is always going to move from a hot place to a cold place, but at least insulation lets us control how quickly that happens.
Also the limit on air sourced heat pumps in cold conditions is basically caused by water freezing on the evaporator coils, effectively adding a layer of insulation that limits how much energy can be drawn from the air, we’re not really limited by the refrigerants. As other have mentioned you dig down to find a better source of heat, and often you don’t even need to dig far, a 20-30cm trench is often enough. Although in super cold climates you’ll need to go deeper to make sure your through the frost layer in the winter.
I covered that in the rest of my post. Most of the time, heating involves a much bigger temperature gradient than cooling. And even though you can use a heat pump, most houses don't use one. (I love the tech personally). Meanwhile cooling always uses a heat pump, so almost every air-conditioned house is using more efficient tech than a heated house. While operating on a smaller temperature delta.
> There is no passive manner that can allow you to cool a space surrounded by a hotter space
Insulation works just as well to keep heat out as it does to keep heat in.