Window screens

[james_s]

They're not electronic but they are technology and this is the most worldwide forum I'm on. I was chatting with my British friend recently and he was complaining about the warm weather and not being able to open windows because of all the bugs getting in the house so I asked if he needed new window screens and he said he didn't have any and that they aren't really a thing there at all. I was surprised by this, in the US and Canada screens on the windows and screen doors on sliding glass patio doors are universal, I've never seen a house built in the last ~75 years that didn't at least originally have them. It's a very simple technology, they're inexpensive, low maintenance, easy to retrofit and practically invisible. We have them in various designs for all styles of windows, even special roll-up screens for windows and hatches on RVs (caravans) and boats. The UK has bugs very similar to those here in the USA, so why are window screens not a thing there? Are people simply not aware they exist? I'd have thought the relative rarity of air conditioning in that part of the world would make screens even more compelling. Bugs entering the house are a nuisance, even if they're not the kind that bite or sting.

Do other parts of the world not have them either?

[Ed.Kloonk]

Fly screens (as we call them) are all fun and games until you have a cat.

[Circlotron]

Maybe climate change has brought bugs to areas that historically were not a problem?

[james_s]

I find it unlikely that the UK didn't have flying insects until recently.

Yeah the screens can be a challenge with cats, but that can be mitigated by not opening the window that the cat likes to sit in, and put some double sided tape on the sills of the windows you do want to open. Most cats hate stepping on anything sticky and will quickly learn to avoid those windows. Mine are geriatric at this point and can no longer jump up to most of the windows.

[TimFox]

On my first visit to Germany, ca. 1990 during August, I was not surprised that reasonably-priced hotels did not have air conditioning, but I could not believe that they had no screens on the windows to keep the wasps out when trying to cool the room.  Outdoor temperatures were > 32^o C.
Another summer trip to Belgium:  also no screens, but they gave us an electric plug-in chemical dispenser to repel mosquitos.
The worst tar-paper shack in the poorest area of the US has window screens and a screen door.

[Ed.Kloonk]

Here, someone renting a house has the right to insist that the screens are installed and repaired if broken. It tends to be less enforced if said tenant owns nuisance pets.

[MK14]

I find it unlikely that the UK didn't have flying insects until recently.

In years gone by (before global warming and other factors), the UK didn't have too much of a problem with bugs.  The main (rare) exceptions being, bees and sometimes wasps (but relatively rare for them to enter a house).

But the common insect to enter at times (when windows are open), would be house flies.  But you can learn to get rid of them, reasonably easily.  So, maybe once or twice a week, the flies can be dealt with, in various ways.  Including opening a door or window and sort of chasing them (or letting them) out.

But in modern times, the insect populations, are suppose to be increasing in the UK.

Maybe it is because of the (still) relatively mild temperature changes, most of the UK experiences, during the year.  I.e. Never that cold or that hot (although probably with global warming, it can get rather hot, these days).

[Ed.Kloonk]

Maybe it is because of the (still) relatively mild temperature changes, most of the UK experiences, during the year.  I.e. Never that cold or that hot (although probably with global warming, it can get rather hot, these days).

I still get a laugh from that place where for weeks everyone wanders about normally until one really sunny bank holiday. Every park every where everyone was half naked.

[MK14]

I still get a laugh from that place where for weeks everyone wanders about normally until one really sunny bank holiday. Every park every where everyone was half naked.

Also potentially huge traffic jams, with everyone trying to go for the same (limited parking, and space in general at the place), favourite (bank) holiday destinations, such as beaches etc.



Source of picture (weird picture, possibly reversed, as we drive on the left):
https://www.warrington-worldwide.co.uk/2022/04/12/how-to-prepare-for-bank-holiday-traffic-as-20m-drivers-hit-uk-roads/

[Ed.Kloonk]

I still get a laugh from that place where for weeks everyone wanders about normally until one really sunny bank holiday. Every park every where everyone was half naked.

Also potentially huge traffic jams, with everyone trying to go for the same (limited parking, and space in general at the place), favourite (bank) holiday destinations, such as beaches etc.



Source of picture (weird picture, possibly reversed, as we drive on the left):
https://www.warrington-worldwide.co.uk/2022/04/12/how-to-prepare-for-bank-holiday-traffic-as-20m-drivers-hit-uk-roads/

And the one day I picked to visit LDN from our base camp in the middle. Pandemonium.

[Ed.Kloonk]

Source of picture (weird picture, possibly reversed, as we drive on the left):

Why would they reverse that? Are we trying not to offend the Americans or something now?

[MK14]

Source of picture (weird picture, possibly reversed, as we drive on the left):

Why would they reverse that? Are we trying not to offend the Americans or something now?

It seems they got it from a photo stock company (iStock, info in bottom left of picture), so it is probably from a European country, with similar looking cars, who drive on the right.

Also, apart from London (perhaps, and maybe a handful of other very big cities), 5 lane roads in both directions, are not common in the UK.

[themadhippy]

No need for fly screens when you got these,think every house in the 70's had em

[Ed.Kloonk]

No need for fly screens when you got these,think every house in the 70's had em

Every fish and chip shop.

[CatalinaWOW]

Cats and cheap screens made of fiber material may not mix, but screens made of aluminum, or even better copper should shrug off cat attacks.  I would think the extra (very significant) expense would not be an issue for those wanting to get their beloved pets a bit of fresh air without exposing them to the dangers of the outside world.

[Ed.Kloonk]

Cats and cheap screens made of fiber material may not mix, but screens made of aluminum, or even better copper should shrug off cat attacks.  I would think the extra (very significant) expense would not be an issue for those wanting to get their beloved pets a bit of fresh air without exposing them to the dangers of the outside world.

I can tell you that a cup's worth of water on the cats belly when caught hanging on the screen is the best way to fix it. Especially if you've got two cats and the 2nd is thinking about doing it.

[vk6zgo]

I find it unlikely that the UK didn't have flying insects until recently.

Yeah the screens can be a challenge with cats, but that can be mitigated by not opening the window that the cat likes to sit in, and put some double sided tape on the sills of the windows you do want to open. Most cats hate stepping on anything sticky and will quickly learn to avoid those windows. Mine are geriatric at this point and can no longer jump up to most of the windows.

Back in 1971, I was sitting in a "bed-sitter" in Southampton UK, on a rare, pleasant summer's day, with the windows open.
A bumblebee flew in, bumbled around loudly, then flew out again.
I was chuffed, having never seen one before, as we don't have them in Oz.

In turn, they didn't seem to have anything like our annoying bushflies---a few houseflies, for sure, but not in huge numbers.
I remember some sandflies, but not mosquitoes.

[TimFox]

I don't remember the exact year of my German trip mentioned above, but it was during the governmental transition while the Soviet army was still around.
Besides the abnormal heat, even in Berlin (quite a bit north), there was an unprecedented plague of wasps.
Screens would have been useful.

[Someone]

Cats and cheap screens made of fiber material may not mix, but screens made of aluminum, or even better copper should shrug off cat attacks.  I would think the extra (very significant) expense would not be an issue for those wanting to get their beloved pets a bit of fresh air without exposing them to the dangers of the outside world.

Stainless Steel, insignificant price increase over the poly/fibre/filament/plastic alternatives.

[RoGeorge]

We rather rarely have them here, in Romania/EU.  Most often called "mosquito nets".  Almost nonexistent in the past, when the window frames were made out out of wood.

Slowly the wooden frames were replaced with plastic frames (popular name "Termopan", which is a brand AFAIK, with plastic frame and double/triple layers of sealed glass).  The plastic frame windows often have insect-screens, but not always (screens can be eventually ordered after installing).

[Ed.Kloonk]

The English in the days of the Empire used to put mosquito nets on and over the bed in the colonies.

[themadhippy]

I was chuffed, having never seen one before, as we don't have them in Oz.

In turn, they didn't seem to have anything like our annoying bushflies---a few houseflies, for sure, but not in huge numbers.
I remember some sandflies, but not mosquitoes.

if you want to meet the most evil bitey thing just take a trip to the west coast of scotland in summer and introduce yerself to    the wee midge, insect  repellent is useless against them, they just see it as  a condiment.

[CatalinaWOW]

I was surprised to see the comment that stainless steel wasn't that expensive, so did some searches and found that the relative prices of materials has changed a lot since I last bought any a couple of decades ago.

Here in the US fiberglass is the most common and runs about $0.50/sq. ft.  Aluminum next most common $0.42/sq ft.  Next is stainless steel at $1.02 sq. ft. and finally the standard from early to mid 20th century, copper at $3.00 sq. ft.  For you metric zealots remember you are only interested in the price ratios and that math is the same regardless of units.

Given those prices it isn't obvious why fiberglass is used most here.  It is easier to work with (cuts with a knife and is very flexible), but is far less durable than aluminum.  Stainless is not noob friendly but obviously one of the best in terms of durability.  Copper is about like aluminum to work with, and is beautiful, but dang it costs plenty.

I also ran across a product that might be of interest to some, pet-proof fiberglass.

I don't understand why screens aren't used everywhere.  In combination with exhaust fans they allow me to almost totally avoid air conditioning while not suffering from mosquitos, houseflies, bees, wasps and hornets.  In an eco-friendly world they are one of the easiest and cheapest solutions.  And while I agree that bees and wasps can usually be gently herded out, it is a nuisance and SWMBO isn't as tolerant of the six and eight legged sharers of our planet.

[TimFox]

Yes, at these prices window screens qualify as an "appropriate technology", even where air conditioning might not be appropriate.

[james_s]

In years gone by (before global warming and other factors), the UK didn't have too much of a problem with bugs.  The main (rare) exceptions being, bees and sometimes wasps (but relatively rare for them to enter a house).

But the common insect to enter at times (when windows are open), would be house flies.  But you can learn to get rid of them, reasonably easily.  So, maybe once or twice a week, the flies can be dealt with, in various ways.  Including opening a door or window and sort of chasing them (or letting them) out.

But in modern times, the insect populations, are suppose to be increasing in the UK.

Maybe it is because of the (still) relatively mild temperature changes, most of the UK experiences, during the year.  I.e. Never that cold or that hot (although probably with global warming, it can get rather hot, these days).

Global warming has raised the average temperature of the planet only 0.8C per decade since 1981 according to what I've found. That's enough to cause problems but not likely going to be very perceptible to humans or affect the amount of time you'd want to open the windows. Where I live has weather similar to that in the UK and it does seem like our summers are a bit hotter than when I was a kid, but it's always gotten pretty hot for at least a few weeks.

[james_s]

Source of picture (weird picture, possibly reversed, as we drive on the left):

Why would they reverse that? Are we trying not to offend the Americans or something now?

It seems they got it from a photo stock company (iStock, info in bottom left of picture), so it is probably from a European country, with similar looking cars, who drive on the right.

Also, apart from London (perhaps, and maybe a handful of other very big cities), 5 lane roads in both directions, are not common in the UK.

I see a few pickup trucks, quite a few SUVs, and at least a couple of fullsized vans that look rather American, I suspect it may be somewhere in the USA or Canada. The resolution is too low to make out the shape of the license plates or any signage which would be helpful. Whatever the case, stock photos are everywhere in news articles, reminds me of a funny situation during the early parts of the pandemic where there was a stock hospital photo used in a lot of articles and people thinking it was some kind of conspiracy. As if they could just wander into the covid ward of any random hospital and take their own picture of patients.

[MK14]

Global warming has raised the average temperature of the planet only 0.8C per decade since 1981 according to what I've found. That's enough to cause problems but not likely going to be very perceptible to humans or affect the amount of time you'd want to open the windows. Where I live has weather similar to that in the UK and it does seem like our summers are a bit hotter than when I was a kid, but it's always gotten pretty hot for at least a few weeks.

I think that Global warming, average temperature rise, does seem to be rather a lot.

(2023 - 1981) / 10 = 4.2 decades.
4.2 x 0.8 = 3.36 Degrees C average temperature rise, between 1981 and now.

Does seem quite a lot, and not all (or even many) animals, fish, plants and other biological things (e.g. Bacteria), may not be able to adequately cope/adapt in time.

Combined with the (apparently) ever increasing human population count.

Things could go bad (if they haven't already), sooner or later.

You're right, we (as humans) may not be too bothered by it.  Perhaps turning up the A/C a notch or two, or opening windows, increasing electric fan use etc.

But we are relying on the rest of the animal/fish/plant/other kingdoms to provide us with food, fresh/breathable air and all sorts of other things.

Also, some people seem to think, that if we over-crowd the planet (humans), then things like pandemics, will become more frequent.

[TimFox]

For some reason, regions of the Earth that have had substantial problems from global warming (e.g., extended drought) seem to be less than peaceful.
https://theyearsproject.com/latest/is-climate-change-causing-more-wars  and many more studies in recent years.

[MK14]

I see a few pickup trucks, quite a few SUVs, and at least a couple of fullsized vans that look rather American, I suspect it may be somewhere in the USA or Canada. The resolution is too low to make out the shape of the license plates or any signage which would be helpful. Whatever the case, stock photos are everywhere in news articles, reminds me of a funny situation during the early parts of the pandemic where there was a stock hospital photo used in a lot of articles and people thinking it was some kind of conspiracy. As if they could just wander into the covid ward of any random hospital and take their own picture of patients.

There seem to be other version(s) of that picture, with completely different looking vehicles.  So, maybe one of the pictures is the original, they then photoshopped or AI photo changed the picture, to have different vehicle types, to the original picture.  Also, it seems to have too many vehicles, too close together, so may be more made up than real, as such.

The original, seems to be from Lagos.

Here:
https://lagossdgandinvestment.com/glancelagos

[MK14]

For some reason, regions of the Earth that have had substantial problems from global warming (e.g., extended drought) seem to be less than peaceful.
https://theyearsproject.com/latest/is-climate-change-causing-more-wars  and many more studies in recent years.

I have heard that higher temperatures, especially excessive ones, put people under stress, and make arguments more likely.  So, maybe that extends to bigger, regional conflicts and things.

[TimFox]

That plus physical problems, especially drought.
Since biblical times, drought has resulted in migration and conflict.

[MK14]

That plus physical problems, especially drought.
Since biblical times, drought has resulted in migration and conflict.

Ironically, even electronics and computers, generally don't like the heat, either.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

It would be great, if we could all (world wide) band together and invent/construct and pay for massive carbon-dioxide removal techniques, and perhaps then bury the excess CO2, back underground somewhere, out of the way.

Instead governments, seem to go for things like forced LED light ownership and electric vehicles.  Yet, they still need enormous amounts of energy and stuff, to be created in the first place.

E.g. An electric car and its batteries, must use up a huge amount of energy and precious materials, in their construction, and will need to get their electricity and spare parts, from somewhere.  So are they really saving the planet, like governments, seem to be implying (by their forced introduction, in the coming future, in many countries).

[james_s]

For some reason, regions of the Earth that have had substantial problems from global warming (e.g., extended drought) seem to be less than peaceful.
https://theyearsproject.com/latest/is-climate-change-causing-more-wars  and many more studies in recent years.

I never claimed that it doesn't cause problems, only that the warming isn't enough that a person is typically going to walk outside and think "wow it feels warmer than it used to" or be much more likely to open a window. The significant problems are mostly indirect, a small change can cascade and result in larger problems.

[james_s]

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

That's kind of how physics works though. Heat is a bit like static electricity, unless the heat (or electricity) is flowing somewhere, no work is getting done.

[james_s]

I see a few pickup trucks, quite a few SUVs, and at least a couple of fullsized vans that look rather American, I suspect it may be somewhere in the USA or Canada. The resolution is too low to make out the shape of the license plates or any signage which would be helpful. Whatever the case, stock photos are everywhere in news articles, reminds me of a funny situation during the early parts of the pandemic where there was a stock hospital photo used in a lot of articles and people thinking it was some kind of conspiracy. As if they could just wander into the covid ward of any random hospital and take their own picture of patients.

There seem to be other version(s) of that picture, with completely different looking vehicles.  So, maybe one of the pictures is the original, they then photoshopped or AI photo changed the picture, to have different vehicle types, to the original picture.  Also, it seems to have too many vehicles, too close together, so may be more made up than real, as such.

The original, seems to be from Lagos.

Here:
https://lagossdgandinvestment.com/glancelagos

Well that one you can see a few numbers and car emblems and such so it's pretty clear that the picture hasn't been reversed. I doubt it has been altered at all, I've never been to Lagos but I see no reason to suspect it isn't an authentic picture of a highway there.

[Circlotron]

Unusual that the traffic would be backed up in both directions at the same time. Generally everyone is either going to work or coming home. Not impossible of course, just unusual.

[themadhippy]

Not impossible of course, just unusual.

youve never been on the M25 then,especially the bit from the M40-M3,its unusual if 1 carriage way is free running let alone both

[MK14]

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

That's kind of how physics works though. Heat is a bit like static electricity, unless the heat (or electricity) is flowing somewhere, no work is getting done.

My understanding, is that it might be theoretically possible.

Example:
You use a very high efficiency heat pump, to turn the existing temperature into a temperature difference, perhaps using a fifth (or hopefully higher) of the electrical energy, that would have been needed, to create the heating (temperature increase) using resistive heating elements.

You then use that temperature difference to power a thermopile  https://en.wikipedia.org/wiki/Thermoelectric_generator  with perhaps an ...
 

efficiency is approximately 33-37%

can be used.  Then it might be possible, eventually, to make realistic ones, which can 'profitably' extract electricity, out of pure/fixed temperature.

Just that they need to invent, practicable heat-pumps and thermopiles, with the necessary high enough efficiencies, over compatible temperature ranges.

But don't worry.  I've heard about and/or spoken to one or more people, who strongly think that the Physics of what I just said, is relatively impossible and it would never work.

Anyway, as a backup solution.  Perhaps fusion power will be invented one day (by that I mean our own fusion generators, excluding calling solar cells/panels fusion as they use the suns natural fusion energy system).

[IanB]

I was chatting with my British friend recently and he was complaining about the warm weather and not being able to open windows because of all the bugs getting in the house so I asked if he needed new window screens and he said he didn't have any and that they aren't really a thing there at all.

Your friend is correct about screens not being a thing. Firstly, your friend is a wuss. There are a few people who jump up and down and scream: "Ooh, a little flying insect, oh no, how scary!" Most people just shrug and ignore them.

Secondly, most British windows are on hinges and open outwards, making screens impractical to fit. If you tried to open the window, it would hit the screen. Sliding windows are not that common.

Thirdly, flying insects really aren't a thing (at least, not compared to the Eastern USA). Things that come inside during the day: Wasps--not that common, and if they come in you just shoo them out again, or swat them. Flies--same deal. Things that come inside at night: Mosquitoes--depends on the location. Rare in most of the country, but if you live in a mosquito zone, then very annoying. Moths: yeah, well, just ignore them. Crane flies (daddy longlegs): pretty annoying in the season, but harmless. Just ignore them unless you are a girl. Otherwise, squealing is entertaining.

My perspective: I have never cared about having open windows in the summer in Britain, except the one time that I lived an a mosquito area. And then, it was really annoying to splat a mozzie and get a blood stain on the wall 

[CatalinaWOW]

I was chatting with my British friend recently and he was complaining about the warm weather and not being able to open windows because of all the bugs getting in the house so I asked if he needed new window screens and he said he didn't have any and that they aren't really a thing there at all.

Your friend is correct about screens not being a thing. Firstly, your friend is a wuss. There are a few people who jump up and down and scream: "Ooh, a little flying insect, oh no, how scary!" Most people just shrug and ignore them.

Secondly, most British windows are on hinges and open outwards, making screens impractical to fit. If you tried to open the window, it would hit the screen. Sliding windows are not that common.

Thirdly, flying insects really aren't a thing (at least, not compared to the Eastern USA). Things that come inside during the day: Wasps--not that common, and if they come in you just shoo them out again, or swat them. Flies--same deal. Things that come inside at night: Mosquitoes--depends on the location. Rare in most of the country, but if you live in a mosquito zone, then very annoying. Moths: yeah, well, just ignore them. Crane flies (daddy longlegs): pretty annoying in the season, but harmless. Just ignore them unless you are a girl. Otherwise, squealing is entertaining.

My perspective: I have never cared about having open windows in the summer in Britain, except the one time that I lived an a mosquito area. And then, it was really annoying to splat a mozzie and get a blood stain on the wall 

Outward opening windows make fitting screens a bit more difficult, but not that bad.  Simplest solution would be a screen hinged on the same side as the window.  Open window with screen lying against the window (the stowed position), then close the screen. 

I wonder why annoying insects are less common in Britain.  Certainly all climates in the US have them.  Many are totally harmless, but some are very noisy.  Others like June Bugs and Cicadas and grasshoppers are generally a total non issue, but the overwhelming numbers for a week or two each year is a real pain.  If a percent get into the house you are talking about hundreds or thousands of insects with a very significant total volume.  Outdoors they are literally shoveled up for disposal with snow shovels.

You don't have to be a wuss to prefer the bugs outdoors.  Large houseflies can interfere with sleep from noise and they tickle/irritate if they are walking on exposed skin.  And if you know their life cycle (they lay their eggs in dung and the larvae eat it before transforming into the adult fly, which ends up walking around on the same material before going on its merry ventures) having them walk around on your dishes, counters and food is distasteful.  Bees and wasps are a non-issue until one gets trapped between you and a chair or bedding.  And then is life threatening if you are sensitive.  I became sensitized one summer when we had an unusually heavy infestation and was stung on seven separate occasions.  The first was a non issue, and not even particularly painful.  But by the seventh my entire hand and forearm became swollen to more than twice its normal size.  I am not interested in finding the next step in the progression.

[vk6zgo]

Not impossible of course, just unusual.

youve never been on the M25 then,especially the bit from the M40-M3,its unusual if 1 carriage way is free running let alone both

Or Perth, WA.

A lot of people live in the Northern Suburbs & work in the Southern ones, & vice versa, & as well as a lot who live in either set of Suburbs & work in the CBD.
The Mitchell & Kwinana Freeways are quite often choc-a-block in the morning or at evening.

Lagos may be situated similarly geographically to Perth.

[PwrElectronics]

On my first visit to Germany, ca. 1990 during August, I was not surprised that reasonably-priced hotels did not have air conditioning, but I could not believe that they had no screens on the windows to keep the wasps out when trying to cool the room.

My first and so far only trip to Germany in 2008 I was surprised at no AC in the hotel but then I am not traveled out of the US much either.  But, like you I found the lack of screens on the hotel windows odd.  It also surprised me that the hotel windows could be opened fully.  In the US, even if the windows in hotels open, I find they do not open very far so as to avoid kids or drunk adults from falling out.  The office I was visiting there also had opening windows w/o screens and no AC.  Any office building built in the US since probably the 1950s or 60s the windows are not made to open.

I am from Minnesota originally and a rural farm area at that.  No screens would mean the house filled with mosquitoes and biting flies.  Especially the mosquitoes at night.  The local joke was they are so large and numerous they are the state bird.  I still have memories of being bitten repeatedly as a small child in my bed due to a torn screen and eventually crying enough my parents were woken up.

[Stray Electron]

We rather rarely have them here, in Romania/EU.  Most often called "mosquito nets".  Almost nonexistent in the past, when the window frames were made out out of wood.

Slowly the wooden frames were replaced with plastic frames (popular name "Termopan", which is a brand AFAIK, with plastic frame and double/triple layers of sealed glass).  The plastic frame windows often have insect-screens, but not always (screens can be eventually ordered after installing).

   FYI  "mosquito nets"  in the US are five sided fabric nets that are made to hang over a bed and to keep the insects off of anyone in the bed.  They don't see them used much in the US any more other than people that are camping. But my parents and grandparents all used them many years ago. The US Military still issues them for field use.  But before air conditioning many houses were kept as wide open as possible so mosquito nets were common in the early 1900s and before window screens became standard.  If you watch an old movie such as 1930s Tarzan movie you will frequently see mosquito nets in them.

   Both of my parent's parents built new houses in 1934 and 1935 and both had screens in the windows from the start. Every house that I know that was built after that also had screens built in. 

   Insects ARE a problem in England. I've studied parts of Kent where the population steadily dropped for over 300 years after the introduction of African mosquitoes in the 1500s.  Go look up the Romney Marshes if you want to know more.

[Stray Electron]

The local joke was they are so large and numerous they are the state bird.

  My father was a student pilot in Florida in 1940s and he used to tell us that a mosquito landed at the airport one time and they loaded on 10,000 pounds of fuel before they realized that it wasn't an airplane.

[TimFox]

The local joke was they are so large and numerous they are the state bird.

  My father was a student pilot in Florida in 1940s and he used to tell us that a mosquito landed at the airport one time and they loaded on 10,000 pounds of fuel before they realized that it wasn't an airplane.

I'm also originally from Minnesota.  The story is told about the two tourists who ignored advice about the mosquitos and ventured into the woods without precautions.  Two 6-foot mosquitos proceeded to kill them.  One asked the other, "should we take them deeper into the woods to eat them?"--"No, the big mosquitos will take them away from us."

[IanB]

I wonder why annoying insects are less common in Britain.  Certainly all climates in the US have them.

Well, flying insects are not much of a nuisance in southern California. I think because of the desert climate. There are more insects in Britain, for sure.

[Ed.Kloonk]

The local joke was they are so large and numerous they are the state bird.

  My father was a student pilot in Florida in 1940s and he used to tell us that a mosquito landed at the airport one time and they loaded on 10,000 pounds of fuel before they realized that it wasn't an airplane.

I'm also originally from Minnesota.  The story is told about the two tourists who ignored advice about the mosquitos and ventured into the woods without precautions.  Two 6-foot mosquitos proceeded to kill them.  One asked the other, "should we take them deeper into the woods to eat them?"--"No, the big mosquitos will take them away from us."

Yikes!

[jpanhalt]

I'm also originally from Minnesota.  The story is told about the two tourists who ignored advice about the mosquitos and ventured into the woods without precautions.  Two 6-foot mosquitos proceeded to kill them.  One asked the other, "should we take them deeper into the woods to eat them?"--"No, the big mosquitos will take them away from us."

My first job was in Minnesota (raised in California).  One of the older members of the group said an early explorer wrote in his diary, "It takes a brave man on a fast horse to cross Minnesota in the Summer."  He attributed that to Lewis and Clark, but I haven't confirmed that attribution.

[TimFox]

The Lewis and Clark expedition did not go through the modern state of Minnesota, but they did go through what are now North and South Dakota after leaving the Mississippi River at the boundary between modern Illinois and Missouri.

[CatalinaWOW]

I wonder why annoying insects are less common in Britain.  Certainly all climates in the US have them.

Well, flying insects are not much of a nuisance in southern California. I think because of the desert climate. There are more insects in Britain, for sure.

It isn't the desert climate.  When I lived in Tucson there were more insects of many varieties than in a lot of other places I have been.  But I lived in the LA basin for quite a while too, and agree that flying insects aren't as big a problem there.  I suspect that that a combination of factors apply - a large urban region probably has far more formal and ad hoc insect control measures in place.  There is sure plenty of insecticide on sale at home improvement stores and many other venues.  And the mostly urbanized terrain must have some damping effect on the insect population.

[coppice]

I was surprised to see the comment that stainless steel wasn't that expensive, so did some searches and found that the relative prices of materials has changed a lot since I last bought any a couple of decades ago.

It depends a lot on where you are. In the UK stainless steel is treated like a precious metal. In East Asia a huge amount of stuff is made from stainless steel, and its not that expensive to have really thick stainless steel.

[Zero999]

Global warming has raised the average temperature of the planet only 0.8C per decade since 1981 according to what I've found. That's enough to cause problems but not likely going to be very perceptible to humans or affect the amount of time you'd want to open the windows. Where I live has weather similar to that in the UK and it does seem like our summers are a bit hotter than when I was a kid, but it's always gotten pretty hot for at least a few weeks.

You've put the decimal point in the wrong place. Global temperatures have risen by 0.08°C per decade.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Some regions have warmed more than others and there are a few places which have actually cooled, due to changes in atmospheric circulation. Care needs to be taken with temperature and precipitation measurements, since human activity can affect the local microclimate. For example, a weather station which was previously in a rural area, which has recently become urbanised, will show an increase in temperature. The Met Office actually subtract 0.2°C from the modern Central England average to account for this.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.

Of course not. It would violate the second law of thermodynamics. There's no way to do work without a temperature differential. It would be like using ambient air pressure to spontaneously make a vacuum. Daily/seasonal changes in temperature and air pressure can be used to generate electricity, but only a tiny amount, as the differential is tiny.

[IanB]

Of course not. It would violate the second law of thermodynamics. There's no way to do work without a temperature differential. It would be like using ambient air pressure to spontaneously make a vacuum. Daily/seasonal changes in temperature and air pressure can be used to generate electricity, but only a tiny amount, as the differential is tiny.

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

[Zero999]

Of course not. It would violate the second law of thermodynamics. There's no way to do work without a temperature differential. It would be like using ambient air pressure to spontaneously make a vacuum. Daily/seasonal changes in temperature and air pressure can be used to generate electricity, but only a tiny amount, as the differential is tiny.

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

4 K to 300 K is a huge temperature differential. You've forgotten that the lower the overall temperature of the system, the higher the maximum theoretical efficiency of the heat engine.

Carnot's theorem.
η_MAX = 1 - T_C/T_H

T_C = 4 K
T_H = 300 K
η_MAX = 1 - 4/300 = 98 ²/₃%

It's obviously impractical to get anywhere near this. The atmosphere returns a huge amount of radiation back to the earth, which is obviously a good thing.

[MK14]

4 K to 300 K is a huge temperature differential. You've forgotten that the lower the overall temperature of the system, the higher the maximum theoretical efficiency of the heat engine.

Carnot's theorem.
η_i = 1 - T_C/T_H

T_C = 4 K
T_H = 300 K
η_i = 1 - 4/300 = 98 ²/₃%

It's obviously impractical to get anywhere near this. The atmosphere returns a huge amount of radiation back to the earth, which is obviously a good thing.

I wondered if a super-conductor, threaded through a massive space elevator, between the planet surface (Earth) and out-space, could conduct enough heat, to make a powerful energy source.  While making my earlier posts in this thread, about using temperature as an energy source.

But unfortunately, the reality seems to be that super-conductors, make very poor thermal conductors.  So I had to throw that idea out of the window.  Which worked, because there was no insect screen in the UK, for it to bounce off (this sentence is a joke).

[james_s]

You've put the decimal point in the wrong place. Global temperatures have risen by 0.08°C per decade.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Whoops, thanks, I thought something looked wrong when I went back to read it.

At any rate I didn't intend for this to turn into a global warming debate, I was merely curious how widespread window screens are, and the answer seems to be a lot less so than I had assumed. They're such a universal thing in my part of the world, and so simple, the technology having existed in some form for thousands of years, I just assumed they were everywhere. Sounds like outside of North America they are not really a thing except in Australia which is not too surprising given what I've heard about insects and other nasty critters there.

[james_s]

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

Even if you ignore the distance, using outer space as a heat sink is is easier said than done. Dissipating heat from spacecraft is a significant challenge due to the fact that conduction and convection are not available, so all you have at your disposal is radiation. It's challenging enough to dissipate more than a few tens of watts here on earth without forced air cooling.

[james_s]

Unusual that the traffic would be backed up in both directions at the same time. Generally everyone is either going to work or coming home. Not impossible of course, just unusual.

That's certainly not unusual here. Try driving from Woodinville, Redmond, Kirkland, etc to Seattle or Everett and through much of the day it will be backed up both ways. It's typically worse in one direction than the other, but a shocking number of people live in the big city and work in the suburbs while another group lives in the suburbs and works in the big city. Beats me why anyone would want to live in an urban city other than for convenient access to a downtown job but some people do seem to love those crowded dirty dumps.

[james_s]

Your friend is correct about screens not being a thing. Firstly, your friend is a wuss. There are a few people who jump up and down and scream: "Ooh, a little flying insect, oh no, how scary!" Most people just shrug and ignore them.

I don't think he's jumping and screaming and scared of them, like me he just finds them to be a nuisance. I certainly don't want bugs in my house, not because I'm afraid of them but because it's extremely distracting and annoying to have a fly buzzing around or a moth attracted to the light of the TV or computer screen or flitting around a light, and flies carry disease (they crawl around on piles of animal shit) so I don't want them crawling around on my food. Also here where I am we have a large number of mosquitoes which love my blood and eat me alive given the chance, and wasps which I'm mildly allergic to which causes a very painful sting with lots of swelling.

[coppice]

In principle, if you could use outer space as your heat sink, where the temperature is about 4 K, then you could have quite a nice temperature differential of 300 K or so. Not huge, but plenty good enough for heat pumps. Unfortunately, it would require some kind of very efficient radiator with access to clear skies at night. It's a shame there is unlikely to be a way to engineer such a thing.

Even if you ignore the distance, using outer space as a heat sink is is easier said than done. Dissipating heat from spacecraft is a significant challenge due to the fact that conduction and convection are not available, so all you have at your disposal is radiation. It's challenging enough to dissipate more than a few tens of watts here on earth without forced air cooling.

There are a bunch of videos on YouTube where people have experimented with various coatings on a shaded surface to radiate upwards to space as an air con. They are interesting experiments, but get too small a result to be useful.

[Ed.Kloonk]

You've put the decimal point in the wrong place. Global temperatures have risen by 0.08°C per decade.
https://www.climate.gov/news-features/understanding-climate/climate-change-global-temperature

Whoops, thanks, I thought something looked wrong when I went back to read it.

That how it starts! 

 

[IanB]

I don't think he's jumping and screaming and scared of them, like me he just finds them to be a nuisance. I certainly don't want bugs in my house, not because I'm afraid of them but because it's extremely distracting and annoying to have a fly buzzing around or a moth attracted to the light of the TV or computer screen or flitting around a light, and flies carry disease (they crawl around on piles of animal shit) so I don't want them crawling around on my food. Also here where I am we have a large number of mosquitoes which love my blood and eat me alive given the chance, and wasps which I'm mildly allergic to which causes a very painful sting with lots of swelling.

We do find them to be a nuisance in Britain too, but not excessively so. There are a few factors which make a difference. Firstly, the UK tends to have very defined boundaries between urban areas and rural areas, and most of the rural areas are farmed, and not wild. There are vast numbers of flying insects in the UK, but mostly they tend to keep to their own habitat, and few venture inside houses. Yes, the odd fly or wasp or moth will come inside, but we just live with the annoyance and shrug it off.

On the other hand, if you drive through the countryside in the summer months, your car and windshield will get completely covered in squashed bugs, and it will be a real pain to clean them off. Also, if you go for a walk in parkland or a nature reserve, then swarms of midges will surround you and follow you. As a child I used to find it amusing to run for a distance to leave the midges behind, and then watch as the swarm followed me and regrouped around my head, just like in a cartoon.

[Ed.Kloonk]

On the other hand, if you drive through the countryside in the summer months, your car and windshield will get completely covered in squashed bugs, and it will be a real pain to clean them off.

Driving between Australian capital cities at twilight is a excellent way to fill the car's radiator with blanket of dead insect. Hard to remove.

[IanB]

I don't think he's jumping and screaming and scared of them...

Right, but you may not have seen the reaction of excitable people to crane flies 

I assume they are found in the USA, but when I was growing up they were as populous as CatalinaWOW described cicadas to be. Except that unlike cicadas, crane flies flutter around like crazy giant mosquitoes and give people the heebie-jeebies.

[IanB]

Since I was curious, I found that window screens are absolutely available in the UK, you just have to buy them and fit them.

It seems that mostly they are designed to fit on the inside, and they attach to the frame with velcro or magnets so they are easy to move aside.

[james_s]

I don't think he's jumping and screaming and scared of them...

Right, but you may not have seen the reaction of excitable people to crane flies 

I assume they are found in the USA, but when I was growing up they were as populous as CatalinaWOW described cicadas to be. Except that unlike cicadas, crane flies flutter around like crazy giant mosquitoes and give people the heebie-jeebies.

Yes we have those here, I think they're what my mom used to call galnippers. They're kind of gross but harmless, and when my cats were younger they used to catch them and eat them fairly quickly so any that got into the house didn't last long.

[TimFox]

Since I was curious, I found that window screens are absolutely available in the UK, you just have to buy them and fit them.

It seems that mostly they are designed to fit on the inside, and they attach to the frame with velcro or magnets so they are easy to move aside.

Another style of window screen that is popular in the US is an expanding rectangle, maybe 30 cm high, that goes under the bottom of a raised double-hung window.
Two halves slide past each other to cover a reasonable range of window opening width.
Retail price between $5.00 and $10.00 USD.

[jpanhalt]

Talk about swarming flies...  Lake Erie shore has Mayflies (attachment).  I saw them the first June I lived in the area.  Absolutely amazing.

https://www.facebook.com/people/The-Mayflies-of-Lake-Erie-Official-Site/100063660383987/

Screens help.  BTW, casement windows usually have the screens on the outside.  Windows that fold out have them on the inside.  Mine are on the inside.  They are easier to remove and clean.  That's also are an advantage when wanting to get a good shot at a groundhog or raccoon.

[TimFox]

Another grand tradition in the US:
Especially before air conditioning became ubiquitous, large houses in low-density urban or rural areas would have very large porches (usually in front, sometimes in back) that were screened (with removable screen frames) in summer to provide a ventilated bug-free area, sometimes used for sleeping in very hot weather.
The screen frames were numbered, to be installed in the right place, but as the house aged and became less Cartesian, one would have to remember which number screen went in which numbered location to fit the new geometry.

[PlainName]

We don't have a fly problem here. In fact, the more the merrier!

[jpanhalt]

Maybe God protects the righteous?

Edit:
Pope Leo X died of malaria in 1521.
Pope Sixtus V died of malaria in 1590.
Giambattista Castana was elected Pope Urban VII in 1590, but died of malaria before his coronation.
In 1623, when the Sacred College of Cardinals was convened to choose a successor to Pope Gregory XV, malaria felled many of these clergymen.

[EPAIII]

CO2 is not a pollutant. It is an absolute necessity for plant life.

CO2 levels are just barely just above their all time, in the entire history of the planet, low level. If we remove much of it, we will need a new food source because the plants will start dying out. And then the animals. And then, guess who!

Oh, and the oxygen, which the plants make, will run out too! Choke! Gasp!

Somebody needs to actually think this thing out. NOW!

That plus physical problems, especially drought.
Since biblical times, drought has resulted in migration and conflict.

Ironically, even electronics and computers, generally don't like the heat, either.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

It would be great, if we could all (world wide) band together and invent/construct and pay for massive carbon-dioxide removal techniques, and perhaps then bury the excess CO2, back underground somewhere, out of the way.

Instead governments, seem to go for things like forced LED light ownership and electric vehicles.  Yet, they still need enormous amounts of energy and stuff, to be created in the first place.

E.g. An electric car and its batteries, must use up a huge amount of energy and precious materials, in their construction, and will need to get their electricity and spare parts, from somewhere.  So are they really saving the planet, like governments, seem to be implying (by their forced introduction, in the coming future, in many countries).

[EPAIII]

It is simple:

The ones who live on the east side of the city, WORK on the west side.

The ones who live on the west side of the city, WORK on the east side.

The ones who live on the north side of the city, WORK on the south side.

and

The ones who live on the south side of the city, WORK on the north side.

See, it's simple.

Unusual that the traffic would be backed up in both directions at the same time. Generally everyone is either going to work or coming home. Not impossible of course, just unusual.

[EPAIII]

Five words:

The second law of thermodynamics.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

That's kind of how physics works though. Heat is a bit like static electricity, unless the heat (or electricity) is flowing somewhere, no work is getting done.

My understanding, is that it might be theoretically possible.

Example:
You use a very high efficiency heat pump, to turn the existing temperature into a temperature difference, perhaps using a fifth (or hopefully higher) of the electrical energy, that would have been needed, to create the heating (temperature increase) using resistive heating elements.

You then use that temperature difference to power a thermopile  https://en.wikipedia.org/wiki/Thermoelectric_generator  with perhaps an ...
 

efficiency is approximately 33-37%

can be used.  Then it might be possible, eventually, to make realistic ones, which can 'profitably' extract electricity, out of pure/fixed temperature.

Just that they need to invent, practicable heat-pumps and thermopiles, with the necessary high enough efficiencies, over compatible temperature ranges.

But don't worry.  I've heard about and/or spoken to one or more people, who strongly think that the Physics of what I just said, is relatively impossible and it would never work.

Anyway, as a backup solution.  Perhaps fusion power will be invented one day (by that I mean our own fusion generators, excluding calling solar cells/panels fusion as they use the suns natural fusion energy system).

[tom66]

Global warming has raised the average temperature of the planet only 0.8C per decade since 1981 according to what I've found. That's enough to cause problems but not likely going to be very perceptible to humans or affect the amount of time you'd want to open the windows. Where I live has weather similar to that in the UK and it does seem like our summers are a bit hotter than when I was a kid, but it's always gotten pretty hot for at least a few weeks.

Without getting too deep into the global warming "debate", there's a difference between average climate warming and actual weather.  So whilst global warming has only had a sub-degree rise so far compared to 1950, the number of days the UK experiences with weather over 30C has increased considerably as a result.

[EPAIII]

OK, Mosquitoes! Never mind any of the exaggerated stories about mosquitoes big enough to saddle and ride. Never mind about 10,000 pounds of fuel being loaded in one. How about a 100% real and COMPLETELY TRUE mosquito story. Mine, and it really did happen. And no exaggeration on the size of them. They were little, small, standard mosquitoes.

I was born and lived the first two decades of my life in Louisiana, on the outskirts of New Orleans. And we had mosquitoes. Just plain, ordinary, smallish mosquitoes. It was a fact of life there and no big deal. Window screens? Heck yes. There were even trucks with fogging machines that would try to eliminate them in your neighborhood if someone paid for it. It did not work well, but people still paid.

One day in the 1960, probably a Friday, after finishing my last class at college I decided to take a ride outside of town. I came to an old fort on the shore line of the Gulf of Mexico a short time before sunset. I got out of the car and walked toward the water. I got half way there (50 meters/yards) and looked at my arm. I am a white skinned and was wearing a short sleeve shirt. And my arm was BLACK. Both my arms were SOLID BLACK. Both arms were almost completely covered with mosquitoes. And they were all biting me.

I wiped them off while turning around and RUNNING as fast as I could back to the car. I don't know how many times I wiped them off my arms but the number got less as I approached the car and got further from the water. I was seriously worried for my very life. I had no idea how many mosquito bites I could endure. I didn't count, but must literally have killed many thousands of them in only a minute or two.

When I got in the car I wiped them off my arms and face and scrambled for the spray can of flying bug spray I had. I probably came close to choking on the bug spray, but I only wanted to kill every last one inside the car. And I drove back home as fast as I could.

Not monsters. Not even the largest mosquitoes I have ever seen. I have seen far larger ones. But thousands and thousands and thousands of them; the shear number of them scared the daylights out of me.

I have traveled around and lived in other parts of the country (the US) and even visited/lived in a couple of others, but have never, ever seen mosquitoes like that any where else. And I never, ever want to.

That's my mosquito story. It is 100% true. I swear it. Not a single syllable of exaggeration. And I really was scared for my very life.

So you can have your Texas mosquitos. Your western mosquitos. Your eastern mosquitos. Your mosquitos from any other area of the world. I don't care about how big they are. Louisiana mosquitos have them beat in shear NUMBERS. And if you don't believe me, I will take you to that coastal Louisiana fort one summer afternoon. But I am staying in the car.

[MK14]

Five words:

The second law of thermodynamics.

Pity we can't just invent something, which can turn heat (temperature) as opposed to temperature differences, into electricity.  Saving burning so much fossil fuels and reducing the global temperatures (maybe or maybe not, as that electricity would eventually be turned back into heat, when it is used, typically).

That's kind of how physics works though. Heat is a bit like static electricity, unless the heat (or electricity) is flowing somewhere, no work is getting done.

My understanding, is that it might be theoretically possible.

Example:
You use a very high efficiency heat pump, to turn the existing temperature into a temperature difference, perhaps using a fifth (or hopefully higher) of the electrical energy, that would have been needed, to create the heating (temperature increase) using resistive heating elements.

You then use that temperature difference to power a thermopile  https://en.wikipedia.org/wiki/Thermoelectric_generator  with perhaps an ...
 

efficiency is approximately 33-37%

can be used.  Then it might be possible, eventually, to make realistic ones, which can 'profitably' extract electricity, out of pure/fixed temperature.

Just that they need to invent, practicable heat-pumps and thermopiles, with the necessary high enough efficiencies, over compatible temperature ranges.

But don't worry.  I've heard about and/or spoken to one or more people, who strongly think that the Physics of what I just said, is relatively impossible and it would never work.

Anyway, as a backup solution.  Perhaps fusion power will be invented one day (by that I mean our own fusion generators, excluding calling solar cells/panels fusion as they use the suns natural fusion energy system).

I've enlarged and set bold, for the bit, I'm replying to, at the very top.

Here is an explanation, of why the heat pumps, I was describing, don't violate the second law of thermodynamics.

Heat pumps operate as a heat engine in reverse, as they do work from an input of electricity to push heat from a cold place to a warm place. This would seemingly violate the Second law of thermodynamics, but the key reason it doesn't is because this heat transfer is not spontaneous; it requires an input of energy to do so.

Source:
https://energyeducation.ca/encyclopedia/Heat_pump

[MK14]

CO2 is not a pollutant. It is an absolute necessity for plant life.

CO2 levels are just barely just above their all time, in the entire history of the planet, low level. If we remove much of it, we will need a new food source because the plants will start dying out. And then the animals. And then, guess who!

Oh, and the oxygen, which the plants make, will run out too! Choke! Gasp!

Somebody needs to actually think this thing out. NOW!

It really needs someone who can explain the details of global warming, which also is getting too off-topic.

I was only suggesting reducing the CO2 levels, down to whatever it needs to be, to restore this planet back to normality.  NOT a total elimination of all CO2.

[Zero999]

Here is an explanation, of why the heat pumps, I was describing, don't violate the second law of thermodynamics.

Heat pumps operate as a heat engine in reverse, as they do work from an input of electricity to push heat from a cold place to a warm place. This would seemingly violate the Second law of thermodynamics, but the key reason it doesn't is because this heat transfer is not spontaneous; it requires an input of energy to do so.

Source:
https://energyeducation.ca/encyclopedia/Heat_pump

But the overall system you've described would violate the second law of thermodynamics, because the end result would be perpetual motion.

You use a very high efficiency heat pump, to turn the existing temperature into a temperature difference, perhaps using a fifth (or hopefully higher) of the electrical energy, that would have been needed, to create the heating (temperature increase) using resistive heating elements.

As I stated in previous post the maximum efficiency of a heat engine is determined by the temperature differential, between the hot and cold sides, with respect to absolute zero. The reverse is also true with a heat pump. The closer the cold side is to absolute zero and the hotter, the hot side is, the more energy is required to shift the same amount of heat, which is also why it's impossible to cool something to 0 K because it would take an infinite amount of energy.

Note Carnot's theorem only determines the maximum efficiency. Real life heat engines never achieve the same efficiency. This means your heat engine wouldn't be able to make enough electricity to power your heat pump, to produce a great enough temperature difference.

[MK14]

Here is an explanation, of why the heat pumps, I was describing, don't violate the second law of thermodynamics.

Heat pumps operate as a heat engine in reverse, as they do work from an input of electricity to push heat from a cold place to a warm place. This would seemingly violate the Second law of thermodynamics, but the key reason it doesn't is because this heat transfer is not spontaneous; it requires an input of energy to do so.

Source:
https://energyeducation.ca/encyclopedia/Heat_pump

But the overall system you've described would violate the second law of thermodynamics, because the end result would be perpetual motion.

You use a very high efficiency heat pump, to turn the existing temperature into a temperature difference, perhaps using a fifth (or hopefully higher) of the electrical energy, that would have been needed, to create the heating (temperature increase) using resistive heating elements.

As I stated in previous post the maximum efficiency of a heat engine is determined by the temperature differential, between the hot and cold sides, with respect to absolute zero. The reverse is also true with a heat pump. The closer the cold side is to absolute zero and the hotter, the hot side is, the more energy is required to shift the same amount of heat, which is also why it's impossible to cool something to 0 K because it would take an infinite amount of energy.

Note Carnot's theorem only determines the maximum efficiency. Real life heat engines never achieve the same efficiency. This means your heat engine wouldn't be able to make enough electricity to power your heat pump, to produce a great enough temperature difference.

I agree with you. (with some lingering doubts, which could probably be resolved, if I spent ages researching it and perhaps performing experiments).

It seems, one of the effects is called COP (Coefficient of performance), see here:
https://en.wikipedia.org/wiki/Coefficient_of_performance

Which (after my rather quick read up on it, so could be a bit or more mistaken) limits the maximum efficiency of heat-pumps, to values which CAN'T exceed 100% over-all efficiency.  Because if it did, it would violate a number of laws of Physics.

So in summary, I agree with you.  It seems, it would break some fundamental laws of Physics, even if I don't yet 100% understand the full Physics explanations, on why it CAN'T happen.

[tom66]

Which (after my rather quick read up on it, so could be a bit or more mistaken) limits the maximum efficiency of heat-pumps, to values which CAN'T exceed 100% over-all efficiency.  Because if it did, it would violate a number of laws of Physics.

No.  The theoretical maximum CoP for a heat pump is around 8.5.   Real world units are limited to about 5 in ideal conditions, and around 3.5-4 in real world conditions.  Those are all above 100% efficiency.  The efficiency figure can exceed 100% because the energy to the room includes that which is extracted from the outdoor environment, which you don't pay for.  I guess you could try to measure the thermal efficiency of the whole system including that outdoor heat source but I'm not sure exactly what that would tell you or if it would be that useful as a figure.

[MK14]

Which (after my rather quick read up on it, so could be a bit or more mistaken) limits the maximum efficiency of heat-pumps, to values which CAN'T exceed 100% over-all efficiency.  Because if it did, it would violate a number of laws of Physics.

No.  The theoretical maximum CoP for a heat pump is around 8.5.   Real world units are limited to about 5 in ideal conditions, and around 3.5-4 in real world conditions.  Those are all above 100% efficiency.  The efficiency figure can exceed 100% because the energy to the room includes that which is extracted from the outdoor environment, which you don't pay for.  I guess you could try to measure the thermal efficiency of the whole system including that outdoor heat source but I'm not sure exactly what that would tell you or if it would be that useful as a figure.

I didn't write/explain it well enough.

I meant, 100% efficiency of the overall system, with a combination of the heat-pump and the thermopile, to turn the heat-difference back into electrical energy.  The idea being to generate more electricity (by inventing much high efficiency heat-pumps and thermopiles, than perhaps are available today), than you initially put into the heat-pumps.
Essentially making a device which turns pure temperate back into electricity, while absorbing some background temperature.

I.e. If a room is at 25 deg C, and you have a discharged car battery.  The car battery could be charged up, but the room temperature would fall to perhaps 10 degrees C.

But as Zero999 (and at least one other in this thread), are pointing out.  The existing laws of Physics, don't allow for this.

I.e. You can't do it, it wouldn't work.  (ok, you can try it, but you would end up putting in more energy (electricity) into the heat-pump, than the thermopile, returns as generated electricity.

Because otherwise, it would be more than 100% efficient, overall (i.e. comparing input electricity into mainly the heat-pump, with the generated/outputted electricity from the thermopile).

[IanB]

No.  The theoretical maximum CoP for a heat pump is around 8.5.   Real world units are limited to about 5 in ideal conditions, and around 3.5-4 in real world conditions.  Those are all above 100% efficiency.  The efficiency figure can exceed 100% because the energy to the room includes that which is extracted from the outdoor environment, which you don't pay for.  I guess you could try to measure the thermal efficiency of the whole system including that outdoor heat source but I'm not sure exactly what that would tell you or if it would be that useful as a figure.

But CoP is not efficiency.

To relate to what MK14 was saying, you have a hypothetical Black Box, connected to various high temperature sources on one side, various low temperature sinks on other side, and the box does useful work (mechanical work, electrical work, whatever). Heat flows through the box from the hot sources to the cold sinks. Inside the box can be any contrivances you like, including the use of heat pumps.

The efficiency is the amount of heat converted to work divided by the total amount of heat flowing through the device. Conservation of energy says that the maximum efficiency cannot be greater than 100%. Other laws of thermodynamics say you cannot even reach 100%.

[tom66]

No.  The theoretical maximum CoP for a heat pump is around 8.5.   Real world units are limited to about 5 in ideal conditions, and around 3.5-4 in real world conditions.  Those are all above 100% efficiency.  The efficiency figure can exceed 100% because the energy to the room includes that which is extracted from the outdoor environment, which you don't pay for.  I guess you could try to measure the thermal efficiency of the whole system including that outdoor heat source but I'm not sure exactly what that would tell you or if it would be that useful as a figure.

But CoP is not efficiency.

To relate to what MK14 was saying, you have a hypothetical Black Box, connected to various high temperature sources on one side, various low temperature sinks on other side, and the box does useful work (mechanical work, electrical work, whatever). Inside the box can be any contrivance you like, including the use of heat pumps.

The efficiency is the amount of heat converted to work divided by the total amount of heat flowing through the device. Conservation of energy says that the maximum efficiency cannot be greater than 100%. Other laws of thermodynamics say you cannot even reach 100%.

I agree, ultimately the heat is just moved so it has to come from somewhere.  I guess such a system would probably approach 100% efficiency at a CoP of >8.5 (haven't done the maths, just intuition).   However, I'm not sure what that would tell you.  Maybe give you a figure of merit for the performance of such a system?  Sounds more like a scientific curiosity than a useful measurement.

[IanB]

I agree, ultimately the heat is just moved so it has to come from somewhere.  I guess such a system would probably approach 100% efficiency at a CoP of >8.5 (haven't done the maths, just intuition).   However, I'm not sure what that would tell you.  Maybe give you a figure of merit for the performance of such a system?  Sounds more like a scientific curiosity than a useful measurement.

Engineering comes into it. Every improvement in efficiency comes at a cost (of design, of manufacture, of materials). At some point, the increased cost outweighs the benefit.

[MK14]

I agree, ultimately the heat is just moved so it has to come from somewhere.  I guess such a system would probably approach 100% efficiency at a CoP of >8.5 (haven't done the maths, just intuition).   However, I'm not sure what that would tell you.  Maybe give you a figure of merit for the performance of such a system?  Sounds more like a scientific curiosity than a useful measurement.

Presumably, if someone had a great understanding of the gas (Physics) laws.  They could use that (and maybe some other stuff), to calculate the theoretical maximum CoP, at a given input (source) temperature.

I.e.  https://en.wikipedia.org/wiki/Gas_laws

Hence we would know (out of curiosity), what the highest possible CoP value, could be for a perfect heat-pump.  Without violating any laws of Physics, even though technologically speaking, we wouldn't be able to produce a device with such high efficiency ratios.

[tom66]

I agree, ultimately the heat is just moved so it has to come from somewhere.  I guess such a system would probably approach 100% efficiency at a CoP of >8.5 (haven't done the maths, just intuition).   However, I'm not sure what that would tell you.  Maybe give you a figure of merit for the performance of such a system?  Sounds more like a scientific curiosity than a useful measurement.

Engineering comes into it. Every improvement in efficiency comes at a cost (of design, of manufacture, of materials). At some point, the increased cost outweighs the benefit.

But why not just measure the CoP?  That is a far more useful figure for the application of a heat pump. 

[SeanB]

Mosquitos I have many, and you can hear the difference between possibly getting Zika virus, West Nile virus, Chikungunya virus, dengue, and malaria, just from the different varieties of mosquito that fly year round.

[mendip_discovery]

CO2 is not a pollutant. It is an absolute necessity for plant life.

CO2 levels are just barely just above their all time, in the entire history of the planet, low level. If we remove much of it, we will need a new food source because the plants will start dying out. And then the animals. And then, guess who!

Oh, and the oxygen, which the plants make, will run out too! Choke! Gasp!

Somebody needs to actually think this thing out. NOW!

I had a quick google and the data I saw states there has been a massive rise in CO² levels. Given how much we have deforested the planet to further our industrial revolutions. It's not surprising. We need to plant more green stuff.
https://earth.org/data_visualization/a-brief-history-of-co2/

Anyhow, I live in the UK and we don't have a need for window or door screens. We do have occasional spates of lots of flies but not had that for a few years. Though I live in a house where on the hottest day of the year the living room doesnt get beyond 21°C so no need to have the windows open. We do get bees in the house and wasps when it's that time of year but we just learn to let them out.

I have heard of the Scottish "wee midge" but avoided being that far north in the summer so far. I have met thier cousins "Manx Midge" it's all ok being up on the mountain course in the Isle of Man until the wind drops and much like scene from Pitch Black all things change and they begin to devour all life.