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Comment by thot_experiment | Hacker News Reader

This is absolutely doable, I've been off-grid for almost 3 years now with a very minimal setup and for the most part I have no complaints outside of a couple weeks in the dead of winter, and the one week that gets really really hot in the summer. I'm not sure how to calculate my total embodied energy but in terms of electricity I have never used more than 7kWh in a single day, which works out 300W and includes all of my computing needs as well as refrigeration, lighting, minor heating/cooling, some small amount of cooking and at least a couple lattes every day.

On the worst day in winter my consumption is usually ~1kWh, limited by solar production.

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My partner and I have been living "off grid" using PV + battery for electricity for the last 5 years in the Appalachian mountains. We track energy use meticulously. We try to use mostly wood heat in winter, but also have a buried propane tank for supplemental heat and hot water in winter. So that is arguably not fully off grid? We have a 2,400-sq. ft. A-frame house with R-52 insulation in most walls (closed-cell + batt) and low-e glass windows (but, alas, lots of windows). We mostly cook with electric or the woodstove in winter. Our woodstove is a massive, pretty efficient soapstone masonry stove central in the house by design. South-facing windows are backed by local stone floors that capture and radiate heat in winter. The house is angled to allow sun to enter windows in winter and block sun in summer for passive heating/cooling.

The two of us use just under 5kWh / day average electricity. Our big energy use is heat in winter though! Here is the breakdown:

5kWh/day electric * 365 days = 1825 kWh/year electrons

2.5 cords wood (mostly oak) = 17584 kWh/year wood heat

300 gal. liquid propane = 8400 kWh/year propane heat

That's a total of ~27800 kWh/year for the two of us including heat. That's about 76 kWh/day or 38 kWh/day per person on average. *This includes charging my e-bike for my work commute--but we also have a gas car so not nearly all transportation energy costs.[edited to add this]

I can't see any way to go much lower than that without freezing in the winter. 2 kWh/day seems crazy low to me.

The easiest way to go lower is to live in a smaller house. Two people don't need 2,400 square feet.

a smaller house, and fewer exterior walls. common walls instead of all exterior walls drastically reduce heating requirements.

i understand that probably doesn't fit OP's lifestyle, and i'm not suggesting they move to an apartment. but i think it's important to acknowledge that dense urban living can have significant environmental benefits over the sort of self-sufficient, off-grid, rural lifestyle that's typically regarded as being more environmentally friendly. cities, and specifically apartments, are very efficient.

Cities have never been and will never be sustainable. You can cram 100 people into an apartment building, but you’re never going to be able to grow all of their food in a rooftop garden.

Although high density can be more energy efficient, it’s not the only metric to consider. Apartment dwellers are completely dependent on importing resources, while rural people at least have a chance at breaking the dependency.

You're saying that cities don't have enough surface area to collect the energy for their residents, but that's irrelevant since the energy doesn't have to be collected within the city. There's nothing unsustainable about a dense city core surrounded by fields.

At best, you've proved that a planet composed entirely of cities is unsustainable. I hope nobody wants that, but sadly some people do.

It's relevant where the resources come from. If a city depends on importing from nearby or distant fields (as well as distant mines and factories), what happens if the people who live in those places do not want their land exploited for the benefit of city dwellers? That is why civilization is based on violence: https://derrickjensen.org/endgame/premises/

Higher density living reduces heating costs... but it also increases summer cooling costs.

I don’t see how 2 people living in a 500 square foot house in the mountains would have significant cooling needs.

If you’re talking about high density in a concrete city, then cooling is a problem.

That's almost three times the size of my family's home.

> low-e glass windows > South-facing windows are backed by local stone floors that capture and radiate heat in winter.

Have you done any analysis or testing on low-e vs normal glass windows in the wintertime? In summer, obviously you want the low-e glass to block the radiant energy. But in the winter, you'd want to allow that radiant energy through, which the low-e glass is not doing.

It seems like low-e glass is only good for summer, and not winter. Have you put any thought into this? Maybe I am missing something crucial about the situation though.

> But in the winter, you'd want to allow that radiant energy through, which the low-e glass is not doing.

Low-E glass reduces inside heat radiating to the outside, too. You can find many articles online discussing the advantages during winter/heating season if you look.

I tested a couple years with/without a tinting film on my west-facing windows (under mini-blinds) and noticed a very, very small increase in winter heating costs, with a big decrease in summer cooling costs, and more consistent temperatures throughout the day in both seasons, which is a benefit in itself (you can use a lower-capacity HVAC system). I suspect a proper upgrade to low-E windows (or at least tinting ALL my windows) would have done much better.

The article suggests aiming for 2 kWh per hour (why don't they just say 2 kW?), not 2 kWh per day. So you're already there: 38 kWh/person/day = 1.6 kW/person

I'm not entirely sure if the article intends to measure embodied energy, though, which your calculations don't capture.

If you aimed to reduce your heat requirements further you can either improve the insulation or reduce your living space (or add a person to improve efficiency :P).

For comparison, we're currently working on our home (bought last year around this time). The new insulation will be U=0.1455 for walls & roof (R-68?) and U=0.29 to the basement. I don't recall the values for windows & the front door. We'll also replace oil with a heat pump and add a ventilation system with heat exchanger. And we only have 1500sqft for two (no additions planned). That will probably be still miles away from those 2kWh/d/person, but much better than the status quo (~2.5kW of heat alone, per person).

Obviously you're already in a good ball park, but GPs value of 2kWh/d/person is just really amazing.

> Obviously you're already in a good ball park, but GPs value of 2kWh/d/person is just really amazing.

It's 2kW/person, or 2kWh/h/person, or 48kWh/d/person

You are of course right, 48kWh/d/person is what the article is all about (& I'm perfectly aware of that).

But as GP[0] replied to GGP

> 2 kWh/day seems crazy low

I was under the impression that he was actually pondering a much better personal energy consumption of 83W/person. And yeah, I'm inclined to say that (with our current level of technology) achieving this number without lowering standard of living might be nearly impossible in many climate zones.

The rest of my comment is more generic.

[0] GP: https://news.ycombinator.com/item?id=32911031

The article mentions "no more than 2,000 watts (i.e. 2 kWh per hour or 48 kWh per day) by the year 2050, without lowering their standard of living" so it is not 2kWh/day but 2kWh/hour. You are already below it in your household.

There are still a lot of omitted factors in the above accounting. The car's petrol use was mentioned but not added, then you have all the embodied energy in the food and other consumed items that were never included. Finally all the energy in the construction and maintenance of infrastructure used, such as roads and internet.

48kWh/day is not hard to achieve at all. That’s just about what my solar array produces and that’s more or less energy neutral for our household. We are far from energy misers as well.

Some of it depends on the local climate and other factors that you don’t have a lot of control over though.

That 48kWh/day is supposed to include the energy used to make all of the objects you own and use though, not just your household energy usage. It takes a lot of energy to produce a house or car just to name two examples.

note that the example in the article of a swiss person's 5.1KW usage includes only 0.6KW of electical power draw, with the rest coming from other sources.

> I can't see any way to go much lower than that without freezing in the winter. 2 kWh/day seems crazy low to me.

Apart from insulation energy required for heating changes massively with local climate and scales directly with living space. So directly comparing those numbers without additional information is quite meaningless.

Here in Germany, which seems to have a roughly similar climate, ~120kwh/m2 and year is the average for a detached home. Modern buildings are usually a lot less though, 30-50 kWh/m2year seems standard. With specialised construction ('passive house') and heatpumps 10 kWh/m2year is well feasible.

Could district heating (https://en.wikipedia.org/wiki/District_heating) help? I'm from the US so I'm not familiar with the idea in practice.

> I can't see any way to go much lower than that without freezing in the winter.

Since your house is very large for just two people, you could occupy only a fraction of it, and heat only that part. Or, just move to a smaller house.

as others pointed out i misread the article, which says 2kwh per hour. indeed that is easily do-able.

So easy enough if building a new small house or a cabin.

The US has many many houses with 4000+ square feet, and no good way to heat it cool outside if AC and a furnace. Are we going to bulldoze all existing houses to meet this goal? What’s the impact of that to the environment?

4,000 sq ft is a 95th percentile home in the US.

https://www.frugalfringe.com/calculators/compare-your-homes-...

> Are we going to bulldoze all existing houses to meet this goal?

Nah, we can retrofit. There are more efficient means of heating/cooling, like mini-splits and heat pumps, insulation, geothermal, etc. With more local and energy-efficient methods (and better insulation) we can get much better efficiencies.

Back in the day, for heating you would have one or two fireplaces. The home was configured so that rooms would get progressively colder away from the heat source. You wouldn't heat the whole home, just one or two rooms, unless there was a special occasion, and then you'd open all the doors. For passive cooling, house facing was critical, as were ventilation, cross-breezes, and later on fans. Homes located in places with extreme temperature shifts were designed to open or close up more or less over the seasons, although they were never "efficient" as they often had no insulation.

The best retrofit would be splitting those mega homes into multiple units. We have a housing crisis after all.

I can't even imagine what a 4000sq ft home looks like. You would start using olde timey names for random rooms. "This is the Conservatory, where we keep our 4th xbox, just in case".

Here is a random one: https://www.zillow.com/homedetails/339-County-Road-4315-Napl...

Often the newer ones have large amounts of "waste space" where hallways are larger, entryways are larger, rooms of course are larger.

> Often the newer ones have large amounts of "waste space" where hallways are larger, entryways are larger, rooms of course are larger.

That house seems to have been built in 1971.

In contrast, here is a brand new home in the same city that is only 1200 sqft.

https://www.zillow.com/homedetails/154-Lt-Rusty-Dr-Naples-TX...?

It seems like someone is building sensibly sized homes there, however rare.

Yeah, the "newer ones" refers to the general trend of McMansions to expand in size even though not much else changes.

Square feet is such a bad measurement of a house, but it's easy to measure and state so it continues unabated.

You also have weird economies of scale where the first 1k sq ft of a house is much more expensive than the second 1k, and that continues basically until you're forced to use other construction methods (steel, for example).

We can require higher standards for new houses. Renovating existing houses will need to focus on the worst ones first. Possibly at sale time.

Four thousand square feet? That's more than ten times the area of the apartment I own back in the UK.

Big is generally easier to keep warm than small thanks to the square cube law, but even in pathological cases it's never harder when scaling up.

Even assuming that 4000 sq ft is spread over 4 levels, that's a ground area of just under 93 m^2, and even in Anchor Point Alaska [0] with 15% panels, that roof can make more on average than the other poster says they're using.

[0] This map doesn't go as far north as Anchorage: https://solargis.com/maps-and-gis-data/download/world

> 4000+ square feet

For reference, that's 370m². In European terms that's probably double what you would expect for a typical family of four.

It is double in US terms too:

https://www.frugalfringe.com/calculators/compare-your-homes-...

https://www.census.gov/construction/chars/highlights.html

> The median size of a new single-family home sold in 2021 was 2,356 square feet.

Hong Kong apartments start at around 120 sq feet (about 11m²), and a family of 6 might live in 550 sq feet (50m²).

Just spray the walls full of aerogel using a process that hasn't been invented yet. Optionally, board half the windows (with aerogel).

Less dramatically they could also close some vents and doors.

Sounds interesting, are you writing down what you are doing somewhere?

If you're off-grid, it's generally because you have to, and you reducing energy consumption is a must.

That said, I have an off-grid office (w/ ~5kw of storage and 1.5kw of solar) and it has definitely changed the way I use energy at home, and what my expectations for my next home will be.

> I'm not sure how to calculate my total embodied energy

It's probably dominated by your vehicle if you have one (decent rule of thumb is abkut equal to the fuel you'd put through an ICE of the same size in a given time)

It is dominated by the infrastructure around the vehicle.

Personal vehicle means space to park it. Space to park it means things are further spread out. This leads to a few inevitabilities:

Things being further spread out means walking and public transit are less feasible.

Individual vehicles means insufficient political support for infrastructure for walking, cycling, and public transit.

The mass required for living (water, food, energy, trash, sewage) has to travel further, and energy = force * distance.

Of course, people’s desire to have backyards and space in general contributes to even more spreading out, but individual cars go hand in hand since they enable being able to consume more space.

In other words, there is no getting around the fact that energy and distance scale with each other, so anything that allows one to consume more space, and hence cause mass to travel more distance, has a multiplier effect on energy consumption.

This is very much true of high density areas.

Although there is somewhat of a counter point to your energy and distance scaling. Without infrastructure and laws forcing the worst possible vehicles, it's quite possible to build a comfortable vehicle which will hang on your wall in a bedroom that does 40-80km/h for several hours a day with the only energy input being the sunlight that falls on it and human effort equivent to a brisk walk.

Similarly a self sufficient homestead doesn't need those utilities and can sustain a person in surpriaingly little area.

We don't have to force the minority who want an actually rural lifestyle to give it up. We just have to apply the same rules and changes that would fix suburbia.

A low-input, no-beef, mostly vegetarian homestead with a 2 story cottage that manages its own utilities and has a 2m wide LEV path 10km to the train station is no more unsustainable than arranging those ingredients into some large farms and a large city. It could be a large mostly-native food forest, or an acre of high yield closed system.

It would be vastly less labour efficient, but if a household wants to dedicate one member's time to agriculture and domestic labour that's fine.

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