solar hook up

[joop]

i know the windows and doors suck.another project to add to the hundreds of others

 

[joop]

i find early spring late fall house hits it's sweet spot for comfort.summer like it's air conditioned .rest of the time hat and coat

 

[joop]

and this winter was milder than usual.buy with your heart instead of your head and your going to have to pay somewhere lol.21c outside and heaters are still running .

 

[maple1]

That's huge. I average about 15, max 25 kWh/day with the heat pumps running...
Before heat pumps I had 10.5 kWh a day...

That would be our max. When outside temps are down to where I should be burning wood instead. Plus the electric water heater and kids are gaming and computers going 24/7 etc.. Non heating season average is 15-20.

 

[woodgeek]

Stone construction varies. My buddy with a stone house had a heating load lower than a 60s to 70s stick construction. Turns out there was an inner and outer stone wall, tied together by thin 'tie stones' and the cavity was filled with gravel (decent R-value per inch). R-value of the assembly was not bad, and the structure was well airsealed after plastering.

A solid stone wall would be terrible R-value.

 

[joop]

walls are not the best,but i do need to change doors and windows ,thats a given they look good but they suck

 

[woodgeek]

walls are not the best,but i do need to change doors and windows ,thats a given they look good but they suck

What is the square footage (or m^2) of your current place?

 

[joop]

rounded of 1500 sqft one floor

 

[begreen]

rounded of 1500 sqft one floor

Holy smokes, it's hard to believe that energy consumption is for a modest-sized place but it shows that heating outdoors is hard and costly.

 

[Ashful]

That's not right. Natural stones have about the lowest R value of any solid material (edit: other than metals, of course), usually less than 0.1 per inch. Don't let the thermal mass fool you.

Yes, it actually is right.

Good heating contractors know better than to apply "R-value" to stone walls. This is not an "R-value" type problem, nor can heating load of a stone house be described very well using such terms. R-value assumes some fixed thermal resistance between inside and outside, which sets up a given delta for a given load.

But stone walls don't work like this, they're nearly always the same temperature. Your windows, doors, and roof act like a normal house, so heat load still changes with outdoor temperature, but not nearly the same as a framed and insulated house.

Think of how your framed house would work, if you set a ~1 million pound block of concrete in the middle of the house, and chilled it to a constant 53F. That will give you some sense of the problem.

 

[gthomas785]

Yes, it actually is right.

Good heating contractors know better than to apply "R-value" to stone walls. This is not an "R-value" type problem, nor can heating load of a stone house be described very well using such terms. R-value assumes some fixed thermal resistance between inside and outside, which sets up a given delta for a given load.

But stone walls don't work like this, they're nearly always the same temperature. Your windows, doors, and roof act like a normal house, so heat load still changes with outdoor temperature, but not nearly the same as a framed and insulated house.

Think of how your framed house would work, if you set a ~1 million pound block of concrete in the middle of the house, and chilled it to a constant 53F. That will give you some sense of the problem.

You've lost me. Stone doesn't stay at 53f so I don't know why that's relevant. I've worked in a few houses with stone walls, and although the large thermal mass of stone does take some time to reach an equilibrium after a month of sub freezing temperatures that wall will be much colder than 53 degrees and it will suck the heat right out of the house. R-value is definitely relevant regardless of the material or the amount of mass.
Now if it's in a basement, different story. The ground acts as a thermal reservoir to keep the temperature pretty constant, with heat passing readily through the stone, concrete, etc foundation.

 

[stoveliker]

@Ashful
Trying to understand this. I get that this is your experience, but I don't understand how you try to cast this into "model understanding".

R-value is the (inverse) number for the thermal resistance of the wall. Are you saying that is not a constant number for a stone wall? (r-value fixed number, but stone walls don't work like this)

The thermal conductivity of a wall in part determines the speed with which the temperature gradient between the two sides establishes itself. The inner surface temperature is in part determined by the slope of that gradient, and by the thermal resistance of the air-stone interface inside your home (assuming an unlimited power inside the home; i.e. having a cold wall won't slowly sink the air temp in the home because of insufficient heating power). I think it's safe to assume that that interfacial resistance is not the issue here. The heat capacity is the energy required to change the temperature of the wall.
I can see that a small conductivity and a high heat capacity could make reaching the equilibration temperature a longer exercise than the characteristic time of the (outside) temperature fluctuations. Is that what you are hinting at?

The bottomline is that any material will eventually take the temperature of the environment it is in. This can be quicker or slower depending on parameters (some, not all, of which are mentioned above). How does your experience translate into this picture?


In my view, the fact is that the cold wall will still be sucking up energy - and more so than an insulated wall (w/ a high r-value); a 53 F large surface will be eating more IR and direct contact (convection) from the warm air in your home than it shines back out. And I presume that if you put a sensitive anemometer at the bottom of those outside walls, you'll see quite a flow of cold air sinking down. And (in my view) the wall stays 53 F (and hence the sinking cold air from those walls) because the R value is so low that the heat you keep putting into the wall gets fluxed out to the outside...? I.e. it's inefficient..

And the fact is that a large concrete block in the middle of the home will eventually warm up to the room air temperature (assuming decoupling from the cold earth below it b\c surely it won't be on a basement). Whether that is after one year I don't know. If you are saying that time constant for your walls is longer than a year, and thus some average temperature is measured on the inside, I could see that. But the fact that it's colder than your room temperature means there is a constant energy flow out. I.e. it's not more energy efficient, even if the temperature you read is constant.

(Edit: I think convection (related to the interface resistance) should not be neglected. - it's been a long time that I did this...)

Edit 2: https://carbonlimited.co.uk/2007/03/05/the-myth-of-stone-walls-as-insulation/

 

[EbS-P]

We have tools like this. I haven’t looked at them
You probably have something similar.

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

 

[joop]

1500sqft is considered large here lol.i took an ir reading in the middle of winter on the interior rock wall 15c

 

[ABMax24]

We have tools like this. I haven’t looked at them
You probably have something similar.

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

PVWatts works in Canada too, we don't have our own and piggyback off that one.

If a person really wants to nerd out this program works awesome, also from the NREL. I used it with mine to confirm my installers numbers on my system before purchase.

Home - System Advisor Model - SAM.

The System Advisor Model (SAM) is a performance and financial model designed to estimate the cost of energy for grid-connected power projects based on installation and operating costs and system design in order to facilitate decision making for people involved in the renewable energy industry.

sam.nrel.gov

 

[hearthon]

Guy on YouTube that I watch has 1700 watts says he wish he had a little more. So I would suggest little over 2000.

 

[Ashful]

You've lost me. Stone doesn't stay at 53f so I don't know why that's relevant.

Yes, it does! If you lived in an old stone house, I'd think you'd know this. Shoot my walls with an IR thermometer at any time of day, at any outside temperature, and you will get 53±1F, all winter long. I have done this, many hundreds of times, in all weather, at all times of day, and the result is ALWAYS 53±1°F in winter. Believe it, or don't, I don't care. But I'm the one actually living in an old stone house, and this is my observation, over many years.

I've worked in a few houses with stone walls, and although the large thermal mass of stone does take some time to reach an equilibrium after a month of sub freezing temperatures that wall will be much colder than 53 degrees and it will suck the heat right out of the house. R-value is definitely relevant regardless of the material or the amount of mass.

How's "worked in a few houses" compare with 50 years of living in and heating a half dozen old stone and brick houses? Of what age were these houses you worked on? What was the material make-up of the walls?

R-value is relevant, with regard to the windows, doors, and roof. But when you have 20" of pre-Portland damp mud-stacked stone sunk eight feet into the wet earth, the impact of cold air incident on the outside of the wall doesn't swing the temperature of the stone in any way that can be modeled by a constant R-value.

This may be different in modern (i.e. built after Civil War) houses built with Portland cement bedding morter, which are not nearly as wet and thermally conductive as the old homes joop and I are discussing here. Our walls are wet, as the bedding mortar is literally mud dug up from the back yard, not modern cement. It wicks water up from the ground, ejecting it out through both sides of the wall, that capillary action serving to further conduct, as well as to cool through evaporation into the home.

Trying to understand this. I get that this is your experience, but I don't understand how you try to cast this into "model understanding".

Experience is all I'm discussing here. You can theorize on the reason behind the observations, but I can tell you the observation is as simple and true as pointing an IR thermometer at a plaster-on-stone wall, many, many, many hundreds of times, in all sorts of weather. They will always read close to 53F in winter months, in this corner of the world. I expect joop will see closer to 50F in his colder climate, as I noted in the prior post, if his house is also pre-Portland construction.

Portland changed everything. It was invented and first put to use in the 1820's in Europe, but it seems no one was importing it to the States until the 1870's. This creates a clean dividing line between "old" stone houses and "new" stone houses, as they're completely different beasts. People who've only worked on Portland stone or brick houses don't really know anything about true "old stone" masonry.

 

[stoveliker]

But when you have 20" of pre-Portland damp mud-stacked stone sunk eight feet into the wet earth, the impact of cold air incident on the outside of the wall doesn't swing the temperature of the stone in any way that can be modeled by a constant R-value.

I think this (thermal contact with the ground, as in the basement scenario mentioned above) is the reason you see what you see. (edit: And I never questioned your observation.)

Regardless, it's inefficient, because of the facile thermal transport of the heat in the home to the outside.

 

[joop]

i can say from my experience the temperature on interior stone is pretty stable ,what it does not do is absorb heat and throw it back like people believe,around stove ya but you would need a flamethrower to heat up the rest of the walls to get any useful heat thrown back.just the way it is,to much mass

 

[gthomas785]

Yes, it does! If you lived in an old stone house, I'd think you'd know this. Shoot my walls with an IR thermometer at any time of day, at any outside temperature, and you will get 53±1F, all winter long. I have done this, many hundreds of times, in all weather, at all times of day, and the result is ALWAYS 53±1°F in winter. Believe it, or don't, I don't care. But I'm the one actually living in an old stone house, and this is my observation, over many years.


How's "worked in a few houses" compare with 50 years of living in and heating a half dozen old stone and brick houses? Of what age were these houses you worked on? What was the material make-up of the walls?

R-value is relevant, with regard to the windows, doors, and roof. But when you have 20" of pre-Portland damp mud-stacked stone sunk eight feet into the wet earth, the impact of cold air incident on the outside of the wall doesn't swing the temperature of the stone in any way that can be modeled by a constant R-value.

This may be different in modern (i.e. built after Civil War) houses built with Portland cement bedding morter, which are not nearly as wet and thermally conductive as the old homes joop and I are discussing here. Our walls are wet, as the bedding mortar is literally mud dug up from the back yard, not modern cement. It wicks water up from the ground, ejecting it out through both sides of the wall, that capillary action serving to further conduct, as well as to cool through evaporation into the home.


Experience is all I'm discussing here. You can theorize on the reason behind the observations, but I can tell you the observation is as simple and true as pointing an IR thermometer at a plaster-on-stone wall, many, many, many hundreds of times, in all sorts of weather. They will always read close to 53F in winter months, in this corner of the world. I expect joop will see closer to 50F in his colder climate, as I noted in the prior post, if his house is also pre-Portland construction.

Portland changed everything. It was invented and first put to use in the 1820's in Europe, but it seems no one was importing it to the States until the 1870's. This creates a clean dividing line between "old" stone houses and "new" stone houses, as they're completely different beasts. People who've only worked on Portland stone or brick houses don't really know anything about true "old stone" masonry.

I'm not disputing your observations. What I am disputing is the conclusion you gleaned from those observations, i.e. that stone walls are "efficient" and that they are somehow not susceptible to the laws of thermodynamics due to being stone. R-value is a measured property of a material; it's not just some theory that only applies in ideal situations.

Because your stone walls are coupled to the ground, and have high thermal conductivity (low R-value), they stay pretty much the same temperature as the ground. That's not surprising at all, and is not in conflict with my observations of other stone walls that may have been less well-coupled to the earth and therefore experienced a wider range of temperatures.
However the constant(ish) temperature does not change the fact that these massive stones absorb and release heat readily. They do release heat to the outdoor air; you just don't notice that part happening because you are inside. What should be obvious is that walls at 53F are continually absorbing quite a bit of heat from your (presumably much warmer than 53F) indoor space. That heat is going somewhere, and it ain't heating up the stone since the stone is staying at 53. So where does the heat go? There's 2 possibilities, the ground or outside. Heat flows from warm to cold, and the ground is about the same temperature as the stone so it's much more likely that all of it ends up being transferred to outside where it's colder. And at the same time, the stone is also absorbing or releasing a smaller but significant amount of heat from/to the ground in order to keep it at 53. You are essentially using low-grade geothermal to supplement the heat for a barely-insulated house. Admittedly that is better than having stone walls that aren't buried in the ground, but don't be fooled into thinking that your walls are somehow just as good as an insulated wall with even an R-5. They're not.

(Edited to fill some in logical leaps I made)

 

[Ashful]

Agreed, guys. While old stone walls become more efficient when the mercury takes a temporary plunge, they are likely almost always less efficient than modern construction with a good R-value. My point was more that the efficiency of these houses improves when it gets colder outside, which is true, not that it is ever "good". Sorry if I over-stated on that point.

 

[woodgeek]

And a double stone wall with a 'rubble' fill in the cavity is actually respectable R-value and better airsealed than most older stick construction! This is also a traditional method.

 

[stoveliker]

It'll be great if insulation can be placed against the wall on the outside underground - recognizing that above ground will be an aesthetic no-no.

We had stone+foam insulation+stone where I grew up. Works great, except for ventilation and humidity. The insulation makes the inside stone really be a thermal reservoir.