Comment by HacklesRaised
20 hours ago
To be fair we are talking about an area of the country that is prone to seismic activity, it does limit the building materials.
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...
> What's the average monthly leccy bill in Phoenix during the summer? $400?
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.
You’re ignoring one critical difference between these two scenarios. Humans, and all human related activities, produce heat as a waste product. It’s much easier, and consumes less additional energy, to heat an occupied space, than to cool it. Thanks to the fact that your average human produces 80W of heat just to stay alive.
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.
> 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.
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.
10 replies →
"cooling a living space is always more costly than heating a living space" Man I wish this was true but it definitely isn't in anyplace that gets significantly cold. Heat pumps are super super efficient at cooling but they get less efficient at heating the colder it gets. Humans and appliances create a pretty negligible amount of heat.
6 replies →
I also point out that Phoenix's "summer" last longer than Berlin's winter:
https://weatherspark.com/y/75981/Average-Weather-in-Berlin-G...
https://weatherspark.com/y/2460/Average-Weather-in-Phoenix-A...
1 reply →
Cooling takes less energy per BTU moved vs heating. In AC/heat pumps that's represented by SEER rating for cooling and HSPF rating for heating (heat pumps). Modern ACs have SEER ratings for 20+ and HSPF ratings for 8+. What it means is that on average, spending 1 BTU equivalent of electrical energy cools down the house by 20 BTU. Similarly for heat pump it means spending 1 BTU of electricity heats up the house by 8 BTU. Electric resistive heating is equivalent of HSPF 1.
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 lot of what you said is intuitively/directionally correct, but misses a lot of important physics related to heat transfer in buildings and operational questions of space heating equipment.
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.
Solar power works very well in summer and can be used for cooling.
It is true that heat is easier to generate. Berlin is considered mild while Phoenix is considered very hot. They just happen to have the same temperature deltas. On the whole, the world spends many, many times more energy heating living spaces than cooling them. The coldest cities people live in just have much larger room temperature deltas than the hottest.
2 replies →
This is a good point that I had not considered, and I will add a few additional thoughts:
* 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)
4 replies →
> So cooling a living space is always more costly than heating a living space
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).
100%. And can be wonderfully done by efficient heatpumps that cover the warmer months too. Also nice correlation between hot and sunny areas which means solar can get you to net zero pretty quick. (Says man looking at his solar panels right now covered with snow.)
you cannot win this argument with the average person who lives in a chilly European country. it just does not compute.
there are whole important cultural lifeways related to opening and closing windows at proper times for efficient cooling and ventilation. these work really well — in Europe — and are treasured traditions.
getting people to accept AC is sort of like trying to convince the average American to go grocery shopping on a bicycle. some may accept the idea but only the most European influenced already.
There's a big gap between "accept AC" and "build a megapolis in a city named after a bird that bursts into flames."
Phoenix is a slow-rolling disaster regardless of whether it's easier to heat or cool a room to comfort.
This is such an interesting perspective that I've never thought about. Thanks!
Recently it was -7C where I lived. Even without heating, my indoor temp didn't go below 15C. In regions where cold temperatures are common, isolation and heat retaining materials are very common. Is preventing heat gain as simple as preventing heat loss?
Yes, insulation works both ways. My garage is unheated and insulated. If I go out there to work on something in the winter I always compare the temperature outside. On a sunny day it might be pleasant outside and freezing in my garage - so I'll open the door and let it warm up.
Insulation makes the house more resistance to temperature change (relative to the inside and outside).
One thing people forget is the delta is very different in the summer and winter. Lets say your thermostat is on 70 year round. If it is 100 degrees out you only have to cool 30 degrees. When it is 0 F out you have a delta of 70 degrees. So for this scenario, expect to use more energy in the winter.
Yes
a greenhouse can heat a space by enough to be comfortable for free, but not cool it. Windows and sunlight matter.
> To be fair we are talking about an area of the country that is prone to seismic activity, it does limit the building materials.
Japan comes to mind as a country that's solved this.
> Where does LA get most of its water? Local sources? I don't think that's the case.
Relevant: https://www.latimes.com/california/story/2025-01-10/as-flame...
Sure Japan did it, so did Mexico. The latter is probably much more important as an example for the US.
https://www.preventionweb.net/news/not-drill-how-1985-disast...
Many of the gouses burning weren't built to current codes, but the cost to retrofit houses to code was insurmountable by any of the owners and apparently by the state or even the nation. So they will just wait for them all to burn and then rebuild them I guess?
Mexico is in the middle of a crippling drought
1 reply →
I would be interested to know how Japan combats wildfires. Historically at least it was quite a big problem, if I recall correctly.
There's plenty of water for Californians in California + The Colorado River.
The problem is that our government has spent ~100 years ensuring that corporations have easier and cheaper access to it so that they can grow feed for farm animals to sell overseas, largely to places like UAE that have sufficiently depleted their own water table as to make it impossible to grow alfalfa, thus worsening the risk of droughts for the sole benefit of the shareholders of these corporations.
Every gov't agency in the US needs to start treating our natural resources as if they belong to all the citizens of the country and not a select few shareholders of whichever corporation can earn the most money by exploiting them.
I won't disagree with you, but it's a big change.
When European descendants started colonizing that part of the world they treated all the resources as free for the taking. You went into nature, developed some land for agriculture, and it became yours by right. The same with the water. It was essentially homesteading.
So water was treated as property the same way the land was. Whoever used it first, owned it. Leaving out the natives because apparently nobody cared about them, it made sense.
How we fix it now within that legal framework is the question.
Hey I'm trying to alleviate this issue from a technical standpoint and am trying to find others to join me. It's no cure-all, but the other paths would upend a century of legal precedence. Shoot me a PM if you're looking for work.
> To be fair we are talking about an area of the country that is prone to seismic activity, it does limit the building materials.
Lisbon was destroyed by an earthquake/tsunami/firestorm combo in 1755 that killed tens of thousands.
When the city was rebuilt, they came up with the idea of using a wooden frame structure for earthquake resistance and masonry walls for fire resistance.
Nowadays, most new buildings seem to use reinforced concrete.
I wonder if American children are taught the story of the three little pigs.
Comments like the last here irritate me. No, we all learn that wood is the only appropriate building material and the Salesforce tower in San Francisco required a whole forest of trees to construct.
The root comment is based on a very dated concept. Of course we can built earthquake resistant megastructures from steel and concrete. A lot of that building technology was created in California. It's either naive or willfully ignorant to think we can't solve this problem.
The issue with those materials is cost. Spread out, suburban design without density is expensive and wood frame construction is a great way to affordably build housing. Wood frame single family houses are not the problem - it's how we design our cities that's the problem.
Hy from Brazil... You know, a poor country.
We make single-level houses with a reinforced concrete structure, because it's cheap.
You know what isn't cheap? Wood. Wood is incredibly expensive to put into a shape, even if you are willing to cut forests down to get it.
7 replies →
What's the alternative? It's not particularly viable to just relocate an entire city.
Then there's the question of where to move them to. Between wildfires, hurricanes, and earthquakes you've eliminated most of the coasts. Much of the rest of the country defines its identity to a significant degree as being opposed to cosmopolitan cities. That doesn't leave a lot of places to move to even if we could just move the cities.
Japan has seismic activity, tsunamis, typhoons, landslides and flooding. Instead of building bunker houses they see homes as transient and utilitarian rather than as long-lasting investments. Perhaps homes in these high risks areas should be treated similarly.