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Comment by jcranmer | Hacker News Reader

The problem here is the high tomorrow in Dallas is supposed to be about 10°F. The typical winter high for Dallas is a bit below 60°F. This means that the demand for heating is about 4-6× what it normally would be for winter.

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Seems to be a combination of many things (a perfect storm...):

• Dwellings are not insulated to the same level as their northern counterparts. Over 60% of houses in Texas have single pane glass.

• Texas seems to rely substantially on heat pumps for residential heating, with fallback to resistive heating. At 10°f very few heat pumps can supply sufficient heat to keep even a decently insulated house properly heated - my guess is that many are using 2-3x less efficient resistive heaters at night.

• Heating peak demands tend to be correlated with the longest time since the sun was last shining... This bodes poorly for solar supply and also self generators - even those with battery backup.

• Texas typically imports from neighboring states... Most of which are in a similar irregular climate.

• Heating requirements for a building vs exterior temperature is non-linear, as are heat pump efficiencies. This is especially pronounced with poor insulation factor.

To put it into context, Quebec has ~46,000MW of peak electrical production capacity for a population of 8.4M. during cold winter days (-30°f) it uses all of that capacity and becomes a net-importer. In Summer months, it uses 1/3 of this.

Texas had peak electrical production capacity of 37,600MW for it's population of 29M.

Greetings from Texas. Yeah, all that is true. You build based on how things usually are, or at least usually WERE when the dwelling was built.

I live in Houston -- very close to downtown, so I'm only about 50 miles from the Gulf of Mexico. This makes it VERY FUCKING WEIRD INDEED that my entire yard is covered in snow, and it is 16F outside. This is NOT Houston weather. It's almost unprecedented -- it's certainly never been anywhere NEARLY this cold in the 26 years I've lived here, and the idea that we really won't be above 32F (0C) for a material amount of time until SATURDAY is really really nuts. In a normal Houston winter, by contrast, we MIGHT see 3-4 nights that freeze. We go years without needing to wrap plants, and I've never bothered to wrap outside pipes before. (Outlying areas to the north and especially northwest of the urban core get as much as 10 degrees F colder, but even so it's not a regular thing.)

So yeah, we're all built here for cooling and not heating. Ambient air temp outside is rarely more than 95, so getting your house to 78 is pretty attainable. But when we get cold snaps, WE certainly notice in our house, which is a relatively new (1997) 3-story townhouse (very vertical; it's about 1800 sq. ft. or 167m^2). It's just not set up to heat evenly or well.

The first problem is just distribution. Our house has a modern 'open' style floorplan, with soaring ceilings in the middle (living) floor. Heat, of course, rises. The upshot is that if you set the thermostat to warm the lower 2 floors to, say, 65F, the 3rd floor main bedroom will be intolerably warm and dry.

As a consequence, a window in our bedroom is open about 2" all winter.

The other gotcha in our house is the floor in the first level, where I have my office (I work from home). It's a stained concrete floor, which is great in the summer because it helps keep the room nice and cool. Unfortunately, it does exactly the same thing in the winter. I'm wearing thick wool socks and long underwear in here now, even though I have a plug-in radiator to supplement the central heating.

Actually, the radiator -- a Delonghi; it works great -- would probably be enough IF the windows were better sealed. My desk is up against a window. My legs feel cold all day in weather like this (well, in cold weather; there hasn't been any weather LIKE THIS before), to the point that last week when it was much warmer (45F during the day) I was wearing sweatpants over jeans.

The house is wonderful and comfortable and attractive. It works GREAT for the vast majority of our weather. It just gets drafty in the winter. And, of course, today I'm concerned that we're going to get rolling outages. Whooo!

At least we have a fireplace. (People laugh about it, but in all honesty having a fire is the easiest way to make the living area comfy without overheating the top floor, just based on where the heat goes. If the house was a little bit bigger, I suspect it would've come with 2 climate control units and proper zoning, which would help a LOT, but as is: just one big zone.)

For open spaces an IR radiative heater - the kind with glowing elements - is better. It won't save much energy, but for comfort - you can actually point it toward your body and warmup it that way without having to heat everything around you first. The fireplace does this too.

Yeah, hence the fireplace in the very open main room.

The radiator in my office -- which is a normal shaped room with maybe an 8 foot ceiling -- does very well.

> the kind with glowing elements

There are far-infrared ceramic heaters that don't glow. Less smell and more energy converted into radiation instead of warm air.

> The first problem is just distribution. Our house has a modern 'open' style floorplan, with soaring ceilings in the middle (living) floor. Heat, of course, rises.

This style of house made so that people can feel rich and high status while wasting enormous amounts of energy to heat and cool is an affront to our future generations.

And it’s almost inescapable unless you’re interested in custom building or buying an old house.

You seem nice.

It wasn’t a personal comment. I’ve seen it in all the houses built in the past 3 decades, coast to coast. Makes no sense thermodynamically. Obviously it sells better than a house that wastes less energy.

"So that people can feel rich and high status" is an insulting way to phrase "has a different set of architectural preferences than I do."

It heats and cools far more efficiently than the traditional homes in Houston (mostly pier and beam construction). There's more to home appeal than thermodynamics, especially in a mild climate.

Houston is not a mild climate, based on how much AC usage I’ve seen there.

Conditioning an extra 2 to 12ft above your head is absolutely choosing vanity over energy efficiency.

However, most people don’t even have the choice since they’re making trade offs between various neighborhoods of various income levels, and once you get above a certain income, all the houses are made with open foyers and tall ceilings. The builders wouldn’t be able to sell the more energy efficient homes at as high of a price as the non energy efficient ones, so obviously we’re going to end up with a stock of homes where the all the heat downstairs is constantly going upstairs.

The reason the homes with higher ceilings will sell for a higher price is because people feel a certain way about them. A high ceiling has no practical benefits and is purely for aesthetics at the expense of energy efficiency. My intention isn’t to insult, but I think it is accurate. People do many things to project their status.

From a thermodynamics POV, we're very mild. We only ever really want to cool about 20F. Heating is nominal. Most places to the north end up with significantly more expensive heating needs AND roughly equivalent AC needs.

You are still being insulting, or absurdly reductive. Neither is especially welcome. Normal humans value all sorts of competing concerns when evaluating a home where they may spend many many years. Maybe YOU only value thermodynamics and care nothing for aesthetics, but that doesn't mean people who don't share your POV are only trying to project status or whatever other uncharitable thing you envision.

I'm very much in favour of this kind of aesthetic, but having both the heating on and the window open all winter is sad and should be unnecessary.

To be super clear: the amount of heating actually done in a normal Houston winter day is very very minimal. It's just that enough of it collects in the high point of a tall home that an open window is desirable for balance (and, honestly, humidity).

OP doesn't seem mean at all, just accurate that open floorplans these days are built poorly. When I was shopping for houses, I never saw a good open floorplan. They all had weird angles, flows that didn't make sense, and zero symmetry, and the asymmetry was terrible to. Open floorplans these days aren't built to be nice, they're built to sell.

Did I piss off an architect?

If anyone wants to see what I'm talking about, I think there are some examples here: https://McMansionHell.com Some of them aren't really that bad, but there are some definite atrocities.

I hate open concept with enough fury to heat all of Texas to boiling. They’re clearly built and sold to people who never have had to try to keep kids out of things.

And even worse are houses badly “opened up” - thereby ruining whatever design was originally in place.

Well, as childfree people, that was an appeal.

My home is majority open concept on 2 of 3 floors with high ceilings and even with 3 kids I can say it's more appealing than those 1-room-per-100sqft 80s/90s layouts. Turns out kids are people too and enjoy nice spaces just the same.

Add zoned areas for the rooms that need heat/cold to isolate your usage.

Zoning a house built with a 1 zone system is very expensive, and zoning doesn’t do much when the house looks like this:

https://i.pinimg.com/originals/94/7b/67/947b6734e9ec93809b2c...

“ This style of house made so that people can feel rich and high status while wasting enormous amounts of energy to heat and cool is an affront to our future generations.”

Wow dude. You decided why people want specific things and let us know that it’s an affront to future generations. I’m glad it tops the list over deep sea drilling, paved suburban road jungles, ocean acidification, and dubstep (they will look back and mourn the loss of our sanity in this age, but it’s so addictive...).

Maybe people just walk into a tall place and feel more comfortable in it? Maybe builders and markets respond to purchasers and their response to something that lots of people find more comforting?

Perhaps a hyper efficient off-grid renewable-driven earthen hovel isn’t for everyone?

I live in a small, modest, low ceiling home with zoned temperature management and comprehensive energy usage monitoring. That’s great for me and my family, but it’s a preference.

And, you know what? Open plan high ceilings are nice, especially when you don’t have kids and can hear each other more easily.

I'll add that up here in the great north - we also use combined air conditioner/heat pumps but in most cases spring for the "low temperature" models with a built in defroster and higher pressure refrigerant - allowing them to heat down to -18°f. This would almost never make sense in a southern climate where it happens once every 20 years. Likewise, investing in any high efficiency/dual-source heating setup would not make any financial sense.

Any Texans looking for some guerrilla insulation/heating techniques:

Put up some painters plastic on the inside frames of Windows (with dual sided tape) as this acts like a very rudimentary dual-pane window. Kits exist for this also (apologies for the Canadian link: https://www.amazon.ca/3M-2141W-6-Indoor-Window-Insulator/dp/... )

Next I would look into a propane space heater (sometimes referred to as a garage/barn heater). These can be operated on a standard 20lb tank and can keep a house warm for a day or two on a single tank. Co2 levels are minimal but you should still make sure you have a decent co2 sensor nearby.

>would not make any financial sense.

Yeah, that's what people often miss. We're not prepared for this, and don't build for it, because it almost never happens.

And it'll be 70F on Sunday.

I remember my parents covering my old leaky single-pane windows in our first house with plastic in the winter. It looks goofy, but it's cheap and it really helps. We also had storm windows that we'd replace our screens with in the winter.

We later moved to a house with newer windows that removed this need, and adult me has a ground source heat pump so I'm toasty even with the 15°F weather here.

Anticipating the cold snap, my wife ordered insulating curtains for the big windows on the front of the house, to hang behind the decorative ones.

I figured it was more an example of "must do something" than "activity that will actually help," but I was proven wrong IMMEDIATELY. They've made a material difference (no pun intended), and I'm said I said no when she asked if I wanted some for my office.

She's a keeper :)

Absolutely. We've been keeping each other for almost 20 years.

Bubble wrap produces very decent insulation for single-pane windows.

Plastic or rather polyethylene tarps or sheets, even plastic bags, stapled to Windows around frame help a lot to keep house warm. Another very good trick, is to hang blankets in hallways that don't have doors. It keeps the room where the heat is warmer, and really really helps with drafts. That also helps to survive, if no heat anywhere, and to keep one living space warm To keep water in sinks bathrooms kitchens from freezing, keep the cabinet doors open, and if really cold, keep the water trickling, especially in cold water lines. These tricks can save your pipes from freezing, which is real mess and expensive. Source - Canadian.

> The upshot is that if you set the thermostat to warm the lower 2 floors to, say, 65F, the 3rd floor main bedroom will be intolerably warm and dry.

Every townhouse I've ever lived in had this problem. The thermostat is on the ground floor or 2nd floor, which results in the bedrooms upstairs being oppressively hot. I will drop the temperature by 5+ degrees before retiring for the night. I hear you about the cold office floor - I have hardwood over a slab and I'm thinking of ordering a heating pad like the one the cat has.

There are many intersecting problems here - the main one is that the standard building code in the South requires a minimum of R-15 insulation in the walls, so that's what the builders put in to remain cost-competitive. You can't get much more than that in a wall cavity framed with 2x4's. Builders and owners need to be incentivized to super-insulate. Not necessarily to a "Net Zero" standard, but increasing the minimum to R-21 (which requires going to 2x6 framing) would help in both heating & cooling seasons.

The other problem is that I have had only a single heat pump for the entire house. It would be much better to have a variable-refrigerant-flow (VRF) system where you have multiple "heads" with their own thermostats that run independently (commonly called a Mini-Split although there are differences). And then you can close the doors to rooms that aren't being used, dropping the thermostat in them to reduce usage.

Yeah, you get hosed on insulation if you buy a spec build. Custom homes are often built better, but come at a premium.

Larger townhouses -- say, 2500sqft & up -- are often zones more reasonably, at least here, such that heating/cooling can be managed with more granularity. But doing it really requires multiple units, not a single big unit.

We live in a 1914 house. There's 2 returns on the main floor. We end up with a wide gap among the floors (basement to 3rd floor). I looked into systems that have inflatable bags that block the areas that are warm so the other areas can get more of the hot air.

Something like this: https://www.retrozone.com/Catalog/flexdamper/Pumps.htm I didn't end up doing it and I don't know anybody who has. And it's probably a lot more expensive than opening your window in the winter.

There is probably a generation or two of work to retrofit housing across the US for energy efficiency, which can also address comfort, and health (indoor air quality). This is something that can only be accomplished using a government program like the Green New Deal (especially for rentals).

I lived in a similar structure for a while, a 3 story townhouse with single zone hvac, thermostat on the second floor. What was in that system that made it work was three dampers, one for each the floors. If you can locate the main duct going to each floor, you should be able to add a manually operated damper to reduce flow to the upper floor when heating and reduce flow to the lower floor when cooling. When I switched my system from heat to cool or cool to heat, I would usually make a point of adjusting the dampers, as well as using that as the time to replace the filters. If you don't have dampers at the source, closing the dampers at the registers on the respective floor to 90% should have a similar effect.

We have a sort of dumb zoning already, which is a thermostat on the first floor, but it only allows the first to opt out of whatever heating or cooling is happening in the rest of the house. This is never something we want to do.

Before COVID were were shopping to upgrade, so we're not going to put any more upgrade money into this house, but if we were going to stay I'd absolutely make changes in this.

The manual dampers for the ducts can be as cheap as $20. Why wouldn't you turn off cooling on the ground floor in summer? Heat should rise.

Re: dampers, we generally close 2 of the 3 vents in the 3rd floor for the winter.

Re: the downstairs, unfortunately it warms up quickly on a hot day, and the structure of the house is such that the downstairs room's heat doesn't really have an easy path up.

The other factor is that, in a NORMAL, non-plague year, I'm alone in the house during the work day. If had perfect control of the house climate system, I'd let the upstairs drift to 80 or 82 while keeping my office at 76 or 78, and not start trying to cool the rest of the house until after hours when my wife gets home. Same with heating: just heat down here during the day, and warm the rest of the house in the evening.

December 1989, there wasn't an unbroken water pipe in Houston. Had to use hammers to break up ice waterfall on steps to apartment.

https://www.chron.com/news/houston-weather/article/Photos-Re...

Do you close off the vents in the upstairs rooms? Seems like that would help a lot in the winter.

There are 3: one in the bedroom, one in the vanity area, and one in the actual bath/wc room. We close all the ones except the one in the bath/shower/wc tiny room, bc that is the place where we are often both naked and wet. :)

Hey neighbor, you live in the heights? You are describing my house and neighborhood :D

Still have power here

Montrose, near Taft & Fairview.

As others have pointed out, heating requirements (watt/m^2) are in fact linear which is why it's possible to more or less accurately calculate a building's insulation performance in watt/m^2/K, it's just that there's a grace zone where if it's e.g. 65F outside and you want it to be 72F inside, you might not need to heat at all because the shortfall is covered by solar gains through your windows, internal gains (cooking etc.) and energy stored as thermal mass. That is, the nonlinearity is not in heating needs, but in the efficiency of heating production and the amount of heating you get for free.

Yes that is correct in theory, BTU requirements are linear based on delta temperature with everything else being static.

What doesn't follow is electricity consumption per BTU produced, ie. if your heating source efficiency is non-linear, such as a heat-pump + resistive fallback heating. You can easily consume 8x the amount of electricity with a delta T of 60 than you do at 15.

In reality, outdoor air temperature alone isn't indicative of the entire building heat loss/requirement - ground temperatures don't respond linearly to air temperatures. Likewise, there are some oddities that come into play with high temperature deltas such as phase-change of materials or outright failure in some cases. Precipitation and wind can also affect thermal efficiencies.

A bitter-sweet example for Texans: The snow can actually provide some insulation. It would be worse if you had no snow and similar air temperatures than getting that 12" of fluffy stuff later this week.

Why does Quebec use more electrical power in winter if most (nearly all) of their heating is natural gas/oil based?

IDK what it's like in quebec specifically, but a lot of my friends in Ontario would have multiple space heaters (depending on how many people were around and where they were) that they would use in the winter months for more 'localized' warmth and the HVAC was more about keeping pipes from freezing.

Central heaters may be natural gas/oil based but the blowing fans or water circulation are typically electric. Also people will supplement with electric space heaters for whatever room they are in while keeping the house somewhat colder than they would prefer.

Power is super cheap in Quebec ($0.04/kwh USD) and gas is not, so many people heat their homes to 16-19ºC with gas, then have electric space heaters in their rooms to bring it up to 21-23ºC.

I'm not sure where you're getting your information, but every source I've seen indicates that the majority of heat in Quebec is electric.

This matches my experience, FWIW. When I lived in Ottawa, I occasionally looked at houses and apartment across the river in Quebec and nearly all of them had electric heat.

More data: https://www150.statcan.gc.ca/n1/pub/11-402-x/2007/1741/ceb17...

https://www.cer-rec.gc.ca/en/data-analysis/energy-markets/pr... (see Electricity heading)

https://www.ivey.uwo.ca/energycentre/blog/2019/06/a-closer-l...

Another thing that takes electrical power to heat in the winter is vehicles. In many Canadian cities in the winter it is very common to plug in your car over night so the engine won't be frozen solid in the morning. Forgetting to do this means your car won't start after a cold night.

Electricity cost in Quebec is around USD $0.05/kWh. Combine that with the fact that most alternative heating sources are at a premium (natural gas, propane and oil all cost substantially more in Quebec than they do in, for example, Texas) and the fact that 98% of Electricity is renewable source, that leads to a very heavy proportion of electric heat. It's not uncommon to have residential units exclusively heated by baseboard heaters - the least efficient means as far as energy required per unit of heat - however it's still cheaper to operate on a yearly basis than a natural gas furnace, while costing 20% of that to install/maintain.

There's non heating reasons to use electricity too.

Canada is north. In summer, the sun can set round 11PM and in winter at 330PM

That's a lot of hours of electrical light vs natural

> At 10°f very few heat pumps can supply sufficient heat to keep even a decently insulated house properly heated - my guess is that many are using 2-3x less efficient resistive heaters at night.

How is it possible for heating devices to be less efficient? Where does the waste energy go?

Normally, waste energy in devices powered by electricity means it's lost to heat, but here it would be lost to...?

https://www.sciencelearn.org.nz/resources/241-heat-pumps-and...

Heat pumps use a small amount of energy to move thermal energy, but it's much more efficient than resistive heat. But if they can't move enough heat, they fall back to resistive heat to top it up.

Ohhhh, interesting. Right, that makes sense.

There's no waste heat with resistive heating, but heat pumps use electricity to move heat from outside to inside, and they can add more than 1J of heat using 1J of electricity.

The trick here is that with heat pumps, they aren't generating the heat, just moving it. As such, you can have, e.g. a 1 kW heat pump moving much more than 1 kW of heat. Wheras with a resistive heater, the best you can do is turn 1 kW of electric power into 1 kW of heat output.

> Texas had peak electrical production capacity of 37,600MW for it's population of 29M

Texas delivered a peak of over 60GW last night, before an unprecedented falloff in generating capacity due to weather and grid conditions.

Majority of the difference between consumption and generation is imported. ERCOT is operating at 52,000MW right now, with 37,600 of it being generated on-grid.

No. Texas does not have 15 GW of import capacity.

I was agreeing with your points....until I got to the bit, "Texas typically imports from neighboring states". Not with power. ERCOT is an isolated grid.

It imports from Mexico and neighboring grids.

From ERCOT's own Q&A:

-----------

EEA1

When the reserves drop below 2,300 megawatts, Emergency Energy Alert 1 is activated. That’s when ERCOT communicates to the public and to power generators that the situation is deteriorating.

At this time, ERCOT will import power from other states and from Mexico. This regularly happens during peak summer months and is not new. But right now, because prices are so cheap, and unrelated to the weather, ERCOT was already importing power from Mexico and other power grids.

Rotating outages do not happen during this stage.

EEA2

When the electric reserves drop to 1750 megawatts, other steps are taken to bring on additional capacity, but rotating outages are still not yet activated.

EEA3

When the reserves get to 1,000 megawatts and they are not expected to recover within 30 minutes, ERCOT will then ask electric suppliers like Oncor and Reliant to begin rotating outages to reduce load on the system.

ERCOT said the location of outages would be determined by each provider like Oncor and Reliant.

https://www.wfaa.com/article/weather/texas-power-outages-fre...

The DC ties represent <1.7% of current load. About the size of a single large generating station. ERCOT, by policy (to avoid certain federal regulations), keeps it that way. I guess you're technically right that they can import power, but that is far from the design intent of the system. (Which is stark contrast to the eastern and western interconections, and their internal multistate ISO's.)

Following up on this, I checked ERCOT status this morning and none of the DC ties are moving energy (at a moment when you might expect they'd really like to):

http://www.ercot.com/content/cdr/html/real_time_system_condi...

the Texas Interconnection (operated by ERCOT) is not fully isolated. They have 3 interconnections from Mexico (one of which has only ever been used once), and two with the eastern US.

It is not clear to me if these interconnections are normally used, or only used in Emergency scenarios. I think they are used both. However I have no idea what sort of capacity these have, and if that is enough in cases like this.

The roads here aren’t designed for snow either. My heat went out on Friday and I can’t even get the heater replaced because the trucks that deliver heaters can’t get through the roads.

Would be quite inefficient for municipalities to have plows and salt/sand spreaders sitting around for a decade not being used. Similarly for garages and distributors to carry winter tires.

Texas hit a peak of 69GW of production, not 37. 37 is what we're able to do after a ton of natural gas plants froze over.

Can't edit, but I was wrong on that number being production, that was peak capacity. That was peak capacity. However from my understanding there isn't a ton of interconnect capacity, so I have a hard time believing peak production was only 54% of peak capacity. Do you have a source for your numbers? It seems extremely low.

Energy loss is strongly supralinear in the temperature gradient, so it's probably a lot more than that.

Time-dependent solutions to temperature change across a gradient are exponential decay functions that solve diff eqs based on Newton's law of cooling. It depends mostly on the insulation and the temperature difference.

While it is 10 F outside, the central heating system for my apartment in a 6-story building cannot maintain temperature. It is 66 F and gradually falling. I would guess it would be 2.5kW running 24/7.

25KW more likely

Probably closer to this than 2.5kw. 2.5kw on a decently modern heat pump should be providing 25k btu. About enough to heat a 2000sqft house ~50f over ambient.

I have a 2.4kW heater in my bedroom...

Just in case anyone is about to miss this detail:

That heater probably doesn't run continously.

For a well designed shared system you can get away with less than n x what an individual unit needs.

(That said, I too guess 2.5kW is too small for what GP mentioned.)

Energy loss through an insulator is exactly linear to temperature.

The problem is that people who would have otherwise tolerated 50F temperatures without heating by putting on a sweater are pulling their old oil column heater out of the storage.

Oh you're right.

One other problem is that one of the ways people have been making their heating more efficient is by using heat pumps, and their efficiency gain drops off with lower temperatures until they become no more efficient than the resistive heaters they replaced during the kind of unusually cold weather Texas is apparently seeing. This makes the peak to average power usage problem even worse.

More modern heat pumps can be efficient at up to around -10 degF[1]. Higher efficiency federal/local rebates are not bad across the US, so I wouldn't be surprised if these were installed in some TX homes. It's still a capacity problem if average use is 10hr/day instead of 2hr/day and your house has no gas furnace heating. I would guess most TX (Dallas/Austin) homes probably do have a gas furnace, but maybe not in coastal/south TX (Houston).

[1] https://daikincomfort.com/go/aurora/

Are their heat pumps linked to outside if their efficiency is so affected? The models I see generally pipe underground, where the temperature is mostly stable and isn't affected by a week of unusually cold weather.

The overwhelming majority of heat pumps across the US are air-source (rather than ground-source), so "yes, overwhelmingly".

Energy usage is superlinear below a certain point. As I recall, about 25% of homes in Texas use heat pumps. but below 30-ish degrees, heat pumps don't work and they have to switch to resistance-based heating So, demand will start rising a whole lot faster.

There are newer heat pumps that work below 30 degrees, but they're more expensive and not typically used in Texas for obvious reasons.

Sort of - to understand how extreme a 10 degree high really is we should be comparing it to the high on the typical coldest day of the year, and then consider how many deviations away from that number this event is, not just how it compares to a typical winter day. Probably want to consider the low temps as well.

But on the other hand there are only so many hours in a day to run your HVAC/space heater. So from 8 hours per day, it can go worst case to 3x.

Hm, heating is either switched off/on depending on a thermostat ("bang-bang") or in more sophisticated systems is regulated according to need (modulating control). It might be on 24/7 regardless of whether it's hot or cold, but it's not going to use the same amount of power.

My furnace, which is common in mid level units, is two phase. It’s off, low, high. Basically it starts by modulating off and low. Once low is on 24/7 and it needs more heat, it modules low/high. At peak heat it’s just high all the time.

Upside to being in Indiana is our furnaces are made for this. I think I can keep my house at 70 down to like -30F outside. It’s a pretty expensive furnace though, wouldn’t make sense in Texas.

Even a cheap thirty year old furnace can do that - it was able to keep my house at 80° during the -40 (no need to specify; they’re the same that low!) last year. I actually intentionally drove it to 80 to give me thermal mass if needed but it turned out not to be necessary.

Burning gas is insanely thermodynamically active.

As an addendum, this winter I unfortunately found out that, at very low temperatures, the limiting factor might be the furnace, but it might also be the capacity of the radiators (or underfloor heating, or whatever) to shed heat. Tiny radiators or highly spaced underfloor pipes and it won't matter how fancy your furnace is, there's only so much heat it can distribute.

Radiators are an alternative to, not a part of, a forced air gas furnace.

Gas furnace burns gas, blows around hot air.

Radiator heats water, and pushes that water around to heat rooms via radiators.

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