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> two walls of bricks separated by a cavity

What is "cavity"? In US brickwork, it may be less than an inch, just to break water seepage. As you see in other replies, we put 3" to 5" of fiberglass in our flimsy walls. Thermal mass does not compete with brick, but my right-size furnace must churn many hours to re-heat the plasterboard if I let the house cool.

> why you guys want to live in flimsy wooden boxes.

Wood is very cheap in the US, and even cheaper in Canada, who gladly ships it to the US. You who logged-out centuries ago can not imagine our wood abundance.

The US is a b-i-g place. Shipping bricks long distances is costly. Shipping boards and studs is much cheaper. (Though "board" is all flake-panel now.) Relatively small crews can erect a balloon frame quickly, brick is hard work.

We do not pretend a house is "forever", because our lives change frequently and so do our neighborhoods. Build for a century, and 60 years later the developers bulldoze the small houses and erect tall apartments or office buildings. (My parents' little shack was built just right: a few structural repairs just before it was knocked-in for a mini-mall for all the city-folks moving into the the suburbs.)

And while I don't expect _this_ woods-house to be over-run by expanding Maine population in 2030, it is wood because this plot is 5 acres of spruce/pine begging to be cut-out, and the owner felled and sawed his lumber on-site. This "flimsy wooden box" has withstood yearly winds and snows you hardly ever see on your green island. Three of Glen's sons raised here, and the only permanent mark is a height-chart on an upstairs wall. (Oh, and small toys found in cracks in renovations.) Still on my 1980 roof and siding, with life left in it.
 
PRR said:
> two walls of bricks separated by a cavity

What is "cavity"? In US brickwork, it may be less than an inch, just to break water seepage. As you see in other replies, we put 3" to 5" of fiberglass in our flimsy walls. Thermal mass does not compete with brick, but my right-size furnace must churn many hours to re-heat the plasterboard if I let the house cool.
It is usually the width of a standard brick, about 3 inches
> why you guys want to live in flimsy wooden boxes.

Wood is very cheap in the US, and even cheaper in Canada, who gladly ships it to the US. You who logged-out centuries ago can not imagine our wood abundance.
I must admit I am jealous of your huge wood reserves.
The US is a b-i-g place. Shipping bricks long distances is costly. Shipping boards and studs is much cheaper. (Though "board" is all flake-panel now.) Relatively small crews can erect a balloon frame quickly, brick is hard work.
Which was equally true in England centuries ago. Most places then were built using local materials although I think even the Romans used bricks. I do know a lot of forest was cut down for charcoal burning and a fair bit of oak was used for building the Navy. Even  in the 1800s large quantities of oak were used to build the small coastal ships that carried goods up and down the country. I saw a programme last night that said it took 40 oak trees to build one such boat and there were thousands of them at that time.
We do not pretend a house is "forever", because our lives change frequently and so do our neighborhoods. Build for a century, and 60 years later the developers bulldoze the small houses and erect tall apartments or office buildings. (My parents' little shack was built just right: a few structural repairs just before it was knocked-in for a mini-mall for all the city-folks moving into the the suburbs.)
Most people in the UK move house every few years but I expect we don't have the relentless drive to expand that you do simply because we don't have the space so houses tend to survive much longer. We have begun to embrace alternative building methods. A few years back a bungalow was built nest door to me. I had a wooden frame and an outer skin of bricks. It took a week to build the frame once the foundations were laid and a couple of weeks to do the bricks. Two brick layers laid 10,000 bricks in 2 weeks. There was one young lad who did nothing but keep them supplied with bricks and mortar. It was a hot summer and he worked incredibly hard to keep up with them. They had a 40 gallon oli drum as a water butt. When he got too hot he simply dived in head first to cool off.
And while I don't expect _this_ woods-house to be over-run by expanding Maine population in 2030, it is wood because this plot is 5 acres of spruce/pine begging to be cut-out, and the owner felled and sawed his lumber on-site. This "flimsy wooden box" has withstood yearly winds and snows you hardly ever see on your green island. Three of Glen's sons raised here, and the only permanent mark is a height-chart on an upstairs wall. (Oh, and small toys found in cracks in renovations.) Still on my 1980 roof and siding, with life left in it.
History unfortunately concentrates on people and their silly squabbles. There's a whole other history of regular folk and their use of the materials they have to hand which which rarely gets told.

Cheers

Ian
 
> about 3 inches

OK. 3" fiberglass would be marginally acceptable in NJ, and much of your area gets no colder. Combined with more thermal mass, and less expectation of constant 72 degrees (22 to you) in February, that's fine. Minimum residential in Maine, and several states south, is now over 5" (2x6 studs really 5.5" thick, fairly full of fluff).

> a lot of forest ....building the Navy. ... small coastal ships

That is why England wanted America. The root of one colonial uprising was the King putting the "broad arrow" mark on big trees which the colonialists could not cut for their own settlements. (Lots of trees, but never enough good trees in practical places.) The spit of land I am on, most of history they were cutting pines and bending boats and ships. Pretty much cut them all. That industry failed rather quickly in the 1930s, which is why the town collapsed, roads let decay, and my woods have the unique character they have. The 1930s seedlings shot-up quickly, shaded later growth, so a nearly mono-crop of 70+ YO trees too close together (and now falling). Sadly much of Maine is in similar shape, my logs not worth hauling.
 
alexc said:
I am planning to do an install of something with a 5KW system for around 4500usd, including the legally mandated licensed contractor install (excluding the battery bank installation).

It would need the equivalent of 2.5 'strong sunshine' hours a day to cover my usage.  Plus another 0.5hrs to cover losses.

Next year, I start on the off-grid electrical system  :)
Please keep us updated on how this pans out for you...

2.5 hours of 'strong sunshine'...is this normal / exceptional for where you are? I could argue that the UK *never* has what you might term strong sunshine, even in summer  ;), although undoubtedly solar panels are more forgiving than humans.....
 
ruffrecords said:
It is usually the width of a standard brick, about 3 inches
Cheers

Ian

They are still building on the new-build estate where I am so I might be able to snap a few pics of our craazy brick house for PRR.
I think they have a 'double' cavity now, in that it is brick-cavity-brick-cavity-plasterboard. My roof also had about 3x more insulation in it than the old terrace house we used to rent.

Didn't the romans invent clay bricks? Or was that concrete...
 
ramshackles said:
Didn't the romans invent clay bricks? Or was that concrete...
Bricks date back to 7000-8000 BC (Jericho southern turkey).

Romans used bricks and brought them to the UK. Romans are credited with inventing mortar/cement.

JR 
 
A recent episode of "this old house" went to a brick factory in the N.E. USA - pretty interesting to see how they are made.
 
dmp said:
A recent episode of "this old house" went to a brick factory in the N.E. USA - pretty interesting to see how they are made.
While not a pretty story I recall a few years ago reading about the Chinese government shutting down a brick factory that was using slave labor. Apparently some low level local party official condoned enslaving retarded people and forcing them to work under very difficult conditions (firing bricks). Perhaps he was responsible for their care too.

I suspect it didn't end well for that party official. Even for China that was considered cruel and unusual, while life is still pretty cheap there, not as bad as it was. 

JR
 
> community 'living in the woods' projects such as Tinkers Bubble and the like.

There's plenty of individual in-the-woods stories.

A local favorite is We Took to the Woods by Louise Dickinson Rich. She fell in love with a businessman who had thrown it all over and moved up past Rangely Maine. Very enjoyable read about being way-way-out in the woods, but also connected with people. (The back-story is a little more grim- Ralph died and she wrote to support their children.) While there is a 2007 edition, older copies list for a penny (plus shipping). She wrote quite a few books, My Neck of the Woods (sequel), Only parent (sequel to sequel), books on King Phillips War, lumbering, Vikings, fur, clipper ships....
______________

Re: wood instead of brick....

Remember that north america is NOT pure english. Germans were almost half the total when we were revolting. I don't know if Germans had a tradition of flakeboard on studs. But Scandinavians and many others. If another guy had a better way to build, you considered it. New land, new techniques.

The story is told of Williamsburg, an English settlement. They obviously did not bring much brick, indeed England may have been more wattle and daub (mud) frame infill. But the heavy rain and poor soil of Virginia washed the walls away. They sure did start a brick-works; late Williamsburg is all brick (in the 1940s re-creation). But meanwhile they split trees to cover the daub. When you have to drop large trees to make fields, this is faster payback than hauling clay and making ovens to burn brick hard. Splitting trees is low tools and part-time, running a brickworks is infrastructure and large time.
 
PRR said:
Heat pumping seems to always be marginal. DMP can't fit the acreage needed to pump-up from Wisconsin's cold soil.
What about pump heat from outside air? Basically a fridge connected backwards (the door is open to the outside and you sit by the back, warmed by the heat exchangers); it is very common here. Doesn't take more space than an air-con. Can work both ways for heat in winter, cold air in summer. Efficieny is about 250-300%. Pumping from earth (or subterranean streams) is known here (as "geothermy"), but the cost of installation is most often prohibitive.
 
ramshackles said:
Please keep us updated on how this pans out for you...

2.5 hours of 'strong sunshine'...is this normal / exceptional for where you are? I could argue that the UK *never* has what you might term strong sunshine, even in summer  ;), although undoubtedly solar panels are more forgiving than humans.....

In the 3months of high summer - easy peasy.

In the 9 months of 'pre-winter, winter and post-winter' then surely it can get challenging. On overcast days it will be not be more than an hour or so of proper charging over the whole day light period.

Hence the needs for backup generation - could more accurately be called 'co-generation', as it will used on more than just 'in case of failure'. Even a small wind gen set of 0.5KW can make a big difference to charging .. if the wind blows.

Again, down here, when the sun is not shining, it's likely the wind be blowing! 

This is the wild and woolly sub Tasman Sea area and right on coast.

When she has a will, the forces of nature can get ..  overwhelming!

Recently, my back-of-property 'creek' turned into a roaring, raging river overnight! And back to a gentle creek in the lazy sunshine a few days later.  It was very wild indeed.


At the dimensions I'm talking about,  ie 5KW solar array,  it means that a modest household (like mine!) would certainly need to be mindful ...  very mindful .. of the daily usage vs charge rates and adjust accordingly.

But I think I can make it work. And I won't be cancelling my service until I have it working out right. :)
 
> What about pump heat from outside air?

As I said some posts back, a Maine dealer sold a lot of those and went broke because they had problems. The idea is very valid. Getting enough machinery at a price that makes sense is NOT easy in our frigid air. I'm on the "warm coast", I design my heat for -5F (-20C), but saw -11F (-24C) the first winter. Today DMP's Madison WI is a degree warmer than here, but their record stands at -29F (-34C). (Compare to 5.5F -14.7C record at Paris France; 14.7F -9.6C at London England.) It takes a LOT of compression and air-surface to get heat to flow "up" from -25 to +65. Machinery costs rise and pump-gain drops quickly at low air temps. If you design the heat-pump to degrade to low output on the coldest night, you still need a full-size backup burner. The heat-pump may be great savings in the mild shoulder-seasons but in February you may be 90% gas or electric. (Oil burner would be even more increase of up-front expense.)

According to Wikipedia, a conventional to-air pump is down to 60% output at freezing. It is freezing here, and IMO we have just _begun_ to seriously heat. We will be a lot colder in Feb., when we will have weeks that even the Low Temp to-air pump will be way down on output. Already that means up-sizing 1/60% (1.7X) just for a typical Feb. day. And there's another 20 Deg of cold to fight on a few nights. We want to size about 2.6X the heat we would get from warmer air. Meanwhile CoP (Coefficient of performance) falls from >4 to like 2. At CoP=1 dumb electric heat is the same thing and much less to buy. CoP <2 hardly justifies 2.6X the freon and coils.

My deep-ground is a steady 55F (12C). But I can't pour solid dirt through a heat exchanger, anyway deep here is hard rock. There's water down there and I can (do) pump it up. But it would be more than one well to bring up the amount of water I might need. And disposal is problematic. If I throw the water in the creek I am depleting my drinking/washing water reserve. If I put it down another hole I run afoul of groundwater pollution rules. Closed systems may be legal but need great care and more money. In some soils you can lay an acre with zig-zag pipe and contact enough dirt to absorb some heat (actually cold). This is done down south where temps are not so bad and soil is sometimes thick and cheap. (Yet these often disappoint.) Utterly stupid here b/c frost typically reaches through the thin soil to rock. When soil freezes, water immobile, the thermal capacity becomes nil. 
 
I don't live in Maine so my air based heat pump works just fine.  I researched it before I bought it a few years ago. I've lived in cold states before but figured out that I could move to a warmer state.

In Wisconsin where DMP lives the frostline goes roughly 2' down, so a ground based heat pump would have to locate the heat exchange system more than 2' deep to stay warmer than freezing, and be installed during the summer when ground isn't frozen solid.  ;D

This is a major expense associated with heat pump heating/cooling in colder climates, but after the initial capital investment the higher efficiency is nice. 

JR

PS: Speaking of refrigerators I've always wondered why they didn't make hot water with the heat the pull from inside. If they already connect to cold water plumbing for ice maker, why not run another line to hot water plumbing.
 
How much electricity is needed to run a heat pump system?
i.e. what % of the electricity it would cost to heat directly?
 
dmp said:
How much electricity is needed to run a heat pump system?
i.e. what % of the electricity it would cost to heat directly?
Typically one third to one quarter of the heat produced. So 100W  of electricity useage generates up to 400W of heat.

Cheers

Ian
 
ruffrecords said:
Typically one third to one quarter of the heat produced. So 100W  of electricity useage generates up to 400W of heat.

Cheers

Ian
that's an optimistic view, supported by manufacturers and installers. Indeed, it depends very much on the climate. In the Paris area, it has been evaluated at 2.6 average.
 
In my case I was upgrading from resistance heat, so I enjoyed a significant jump in efficiency, but I do not have clean apples to apples before and after comparisons because around the same time I tightened up air leaks, and converted my bedroom heat to time of day thermostat (still resistance), and rigged up some rube goldberg storm windows.. 

In the South typical older (inexpensive) homes use single pane glass windows, with no exterior storm windows. In the north we'd have at least another layer of glass where our screens go and maybe dual pane window glass.  Since I was too cheap to replace all my windows, I embarked on a DIY project. I made wood frames that nested inside all my windows with two layers of clear plastic film. This made a huge difference in heat loss... Surprisingly these have held up nicely for a couple years already, but i just leave them in place (the help the air conditioner in the summer too)..

Closing up air leaks around the doors made a difference too.

I made a special variant DIY storm window to go around my bedroom air conditioner so I could open up just the bottom half for summer use, but since I double (triple) paned all my other windows in the house I haven't fired up my bedroom air conditioner the last two summers. The large in wall unit in my main room keeps the whole house comfortable, while I use a box fan in the hall to circulate air around the house as needed. 

In my judgement the low hanging fruit is adequate insulation, and someday I may add more in my attic.

JR
 
abbey road d enfer said:
that's an optimistic view, supported by manufacturers and installers. Indeed, it depends very much on the climate. In the Paris area, it has been evaluated at 2.6 average.

it also depends on the heat delivery system. Underfloor heating can use lower temperature water and is more efficient than radiators.

Cheers

Ian
 
> How much electricity is needed to run a heat pump system?

That is the CoP number in the link I cited.

On a nice day, many of JR's days, CoP >4 may be reached. If you need $400 of dumb electric heat, $100 in the heat-pump does the same job.

In our colder climes, CoP falls to 2 or less. Yes, $400 of heat for $200 of pump power looks like free money. But the initial investment may be many thousands, opposed to some hundreds for dumb electric. Lesseee... looks like >$4K for 5-ton hi-SEER compressor with heat-pump ability, coil, lines, and etc. Plus pro installation. That's not too bad on the face of it. If it saves half my propane bill, pay-back is nominally 5 years. I do not know if this first pump I found....

Ah, PDF of numbers. At zero outside I get 10 MBTuh of heat, I need 28 MBTuh. It seems to hold-up my whole house to 20 deg F, which aint bad and covers a lot of days. It would be fun to see my propane man at Xmas and say "Bah, no gas today!". But I'd need him in Feb/March. I'd need to go through a lot of records to figure how much the pump might actually save. As performance declines to 20% output and CoP near 1.5 in my coldest days, I still need essentially same-size backup fire. At the lower temps in the up-central states, this is only shoulder-season economy and not a winter solution.

It does however cover A/C needs as well. I paid $550 more to add A/C to my burner. Never been in Madison, but I gather the hot air runs from Texas to St Louis and Indianapolis, and keeps going. As I do whenever I run though Indy, StLou, or any of that country. Hmmm.. 80 average, 107 record (28/42C), 70+% RH much of the time, you like A/C.

And think of the stresses, a mild fan and fire versus a hard-pumped freon compressor. Moreover the compressor lives outside in heat and bitter cold. Hmmm... this item does come with 10 Year warranty on unit, parts, and lifetime on compressor. That's more than my basic gas-burner. But it was 1/4 the price, and could be replaced with pocket money and a screwdriver.
https://www.alpinehomeair.com/_viewresource.cfm?ID=2612
 
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