Energy Efficient House Building in Fairbanks, Alaska

[byQ]

There is a lot of good house building information coming from Fairbanks, Alaska. Fairbanks and Anchorage are the two biggest towns in Alaska. Anchorage is a small city, really, and is on the coast. Fairbanks is more inland and 300 or 400 miles north of Anchorage. It is smaller and has a town feel about it - no tall buildings and spread out. I've lived in Fairbanks for a short while and only visited Anchorage.

Anchorage is warmed by Japanese ocean currents. Surprisingly it isn't nearly as cold during the winter as one might think. Fairbanks on the other hand does get very cold. So Fairbanks is a great laboratory for applying energy efficient ideas/techniques, ie, "..if it works in Fairbanks it will work in the lower 48..."

This fellow, Thorston Chlupp, has some good information about energy efficient house building. He is learning/applying superhaus principals but trying to build cost effectively, too. I can relate to this.





I've learned a few new things so far, but need to finish watching the videos.
* place windows so they are 40-60% within the framing hole - that is if you have a wall 10" thick the windows should be 4" to 6" within the framing hole. If the window is on the outside of the hole it will lose ~20% more heat.

* walls that allow slow infiltration and exfiltration - ie they let moisture escape.

* thermal shutters should go outside of the window not inside - to avoid icing on windows.

* he's building some sort of rolling gate thermal styrofoam shutters that are very effective (this is new, I've never heard of this).

* HRV systems in North America aren't very good. Euro models should be considered.
* building green walls - that is walls made out of living plants.

The Climate Control Housing Research Center is involved in monitoring some of these energy efficient houses being built. They have a lot of good information on their site, too.
http://www.cchrc.org/

http://www.cchrc.org/podcasts

 

[DougA]

I'm not up on the current trends. I was at the leading edge of this 30 yrs. ago when I built my energy efficient house. Lots of people give advice but you really have to dig through it to find what makes sense and what will work in your particular case. I'm a huge fan of passive solar and thermal mass but that doesn't work at all in Alaska. The video shows exactly that on your post and I wouldn't even click on it to watch it. Just plain wrong for the far north.
I spent a lot of time fighting to get my ideas into reality. Thankfully, everything we did has worked well but there are many things we almost added that would not have been successful. I almost built our house with a concrete roof and a foot of dirt on top. I found someone near me doing exactly that. I went to visit during his construction, saw how he was having a disaster and ditched the idea on the spot.
Just to put another opinion on your points:

Windows that should be located more in than out for 20% savings. OK, but a good low-e double insulated window is between R2 & R3, whereas a good wall would be at least R24. So, if you save 20% of R2, your savings is squat. Good curtains are far better.

Walls that breathe. Great idea but I have never seen anything that allows the correct amount of breathing on a still day vs. a wind storm. Proper sealing is still the way to go. The problem is that so few contractors do a proper job of sealing.

Thermal shutters and rolling shutters are common in parts of Europe and have been for a century. It's not common here so the price is way too high. Generally, they need to be designed into the plans, otherwise they look like sh*t.

HVR - are you talking about ventilation? Most of Europe is way ahead of North America on this because the cost of energy is astronomic in Europe. The same applies to tankless water heaters. I had 2 installed in an office 20 yrs ago and it took me ages to find them. They are just becoming more common in Canada but waaay too expensive. My son just bought a new house with a tankless water heater and the rental was $60/month. He had them remove it and switched to a regular water heater and pays $16./month for rental. There is no way you can save $40./month on gas using tankless so why would anyone consider it? Some ideas are great but not when you work out the $$, either short term or long term.

I've seen lots of green walls. Good idea and I have one very large modified one in my house. My plant wall is just a lot of plants on top of a wall 3' high x 30' long. A true plant wall is porous and made entirely of plants. There are times when I have better things to do than water & care for my plant wall even though I love plants. The practicality and upkeep are more of a problem than most people would accept.

What I have found is that too many ideas are not liveable. IOW, the home owner will not do the upkeep or even utilize the potential. For example, my son's house has a top quality air exchanger. He rarely uses it because it's noisy. How often do owners pull curtains to save energy at night? They just don't 'buy in' to the philosophy unless it's easy or unless you can show them in real time how much money they save. I think that will be a huge thing in the near future with Google buying Nest today. You'll be able to log in to Google and see exactly how much energy is being used by each receptacle in your home. I looked extensively into a new start-up that is supposed to do exactly that but it's smoke and mirrors in that it doesn't take actual electrical usage, it takes the 'estimated' usage. Not good enough for me.

 

[brogsie]

"Walls that breathe. Great idea but I have never seen anything that allows the correct amount of breathing on a still day vs. a wind storm. Proper sealing is still the way to go. The problem is that so few contractors do a proper job of sealing"

Why do the contractors get blamed for everything. How about the home owner did not want to pay the contractor to take the extra time to seal properly?

 

[Highbeam]

"Walls that breathe. Great idea but I have never seen anything that allows the correct amount of breathing on a still day vs. a wind storm. Proper sealing is still the way to go. The problem is that so few contractors do a proper job of sealing"

Why do the contractors get blamed for everything. How about the home owner did not want to pay the contractor to take the extra time to seal properly?

Because the contractor didn't ask and doesn't know any better. Usually.

 

[semipro]

Because the contractor didn't ask and doesn't know any better. Usually.

Also because the homeowner/buyer can't "see" the difference between a we'll constructed "tight" home and one that just looks good.
This is exactly why energy related building codes and house energy efficiency certification is a good thing.

 

[byQ]

1/2 a light bulb to heat his house for 270 days a year, in Fairbanks, he must be doing something right. Than using a masonry heater for those 2-3 months of total Alaskan darkness - to heat water and house. Interesting these guys are putting vertical tanks in houses. And they use water solar panels.

Their tanks are where they are putting in a lot work, ie the central component to getting net zero houses farther north than any other houses. They figure they can build a house with very good insulation (tight) with thermal shutters, a good European HRV, and a solar water system with a big tank placed vertically within the house. Water is used to do most of the heating work. How are they using and gathering hot water?

So they put up 6 to 10 flat plate water solar collectors on the roof. And place a large insulated vertical tank within the house. The hot return water from the collectors is piped into the bottom of the tank and than into a large vertical PVC pipe (the PVC pipe is full of holes). The heated water flows up through the vertical pvc pipe within the water-filled tank until it finds water of a similar temperature and than escapes the pipe through the holes. And the advantage to doing it this way?

The advantage is that within the vertical tank there are distinct layers of water - the top is hot, the middle is warm, and the bottom is cold. They use the top water (>100 F) for showers and faucets, the middle water (80-100 F) is used to run through PEX to provide heat in the slab (hydronic heating) and the cold bottom water is fed back to the flat plate solar collectors (cold water absorbs more energy than warm or hot water).

If they didn't have this pipe system in a vertical tank, the water would be more even in temperature throughout. They are just using physics to seperate the water by temperature and than they are sending the water off to do work in 3 areas - where hot water is desired (faucets), where medium temp water is best (hydronic), and where cold water is best (back to solar collectors).

The big vertical water tank is just another way of using thermal mass within a house. Their heated thermal mass (water in the tank) can be sent off to do work (moved via pex and piping) to maintain the well insulated house.

 

[semipro]

1/2 a light bulb to heat his house for 270 days a year, in Fairbanks, he must be doing something right. Than using a masonry heater for those 2-3 months of total Alaskan darkness - to heat water and house. Interesting these guys are putting vertical tanks in houses. And they use water solar panels.

Their tanks are where they are putting in a lot work, ie the central component to getting net zero houses farther north than any other houses. They figure they can build a house with very good insulation (tight) with thermal shutters, a good European HRV, and a solar water system with a big tank placed vertically within the house. Water is used to do most of the heating work. How are they using and gathering hot water?

So they put up 6 to 10 flat plate water solar collectors on the roof. And place a large insulated vertical tank within the house. The hot return water from the collectors is piped into the bottom of the tank and than into a large vertical PVC pipe (the PVC pipe is full of holes). The heated water flows up through the vertical pvc pipe within the water-filled tank until it finds water of a similar temperature and than escapes the pipe through the holes. And the advantage to doing it this way?

The advantage is that within the vertical tank there are distinct layers of water - the top is hot, the middle is warm, and the bottom is cold. They use the top water (>100 F) for showers and faucets, the middle water (80-100 F) is used to run through PEX to provide heat in the slab (hydronic heating) and the cold bottom water is fed back to the flat plate solar collectors (cold water absorbs more energy than warm or hot water).

If they didn't have this pipe system in a vertical tank, the water would be more even in temperature throughout. They are just using physics to seperate the water by temperature and than they are sending the water off to do work in 3 areas - where hot water is desired (faucets), where medium temp water is best (hydronic), and where cold water is best (back to solar collectors).

The big vertical water tank is just another way of using thermal mass within a house. Their heated thermal mass (water in the tank) can be sent off to do work (moved via pex and piping) to maintain the well insulated house.

Ingenious.
I've often wondered how to store water at different temps for different uses.

 

[byQ]

The advantage to having the tanks right within the house instead of buried is that any heat lost from the tanks goes to heating the house.

Other things I noticed these builders were doing - making thermal mass walls. He explained it by saying you could have 3 walls all with the same R value, say 50. One is of light construction, the next is of medium construction and the third is of dense construction. They all have the same R values so they must be equal?

No, although they have the same R values heat passes through them differently. In the lighter wall heat passes through the fastest (say 5 hours) and in the densest wall heat passes through the slowest (say 18 hours). He is building medium density walls by stuffing the double wall construction with dense cellulose (cost effective material). So it takes heat about 11 hours to pass through his walls. Is the slower heat release an advantage?

Yes its an advantage, because it means less energy going into the wall to replace the heat lost - and any time over 10-12 hours mimics the sun up/sun down cycle so solar energy can recharge the walls, ie the walls take care of maintaining their energy (thus they aren't sucking energy from other sources). Another thing I noticed that he didn't really talk about was the construction of his floors.

They are thermal mass floors - they are topped with rock or tile, and appear to be 4"- 8" thick slab of concrete with pex tubing embedded within for hydronic heating (hot water through tubes). He is doing something different with his floors that I haven't seen done. Under the slab is about a foot of sand. And under the sand is the insulation. I've heard of having a sand thermal mass under a concrete floor (sometimes like 6 feet deep) but when I've seen it they run the PEX coils down towards the bottom of the sand. He heats the slab and heat travels downward to heat the sand.

Why have the sand? Again, the sand provides more thermal mass. In Fairbanks there are extremes of sun. When the sun is extreme he is dumping energy into the slab (and sand) to carry him as long as possible through the no sun season. If he just had a slab it wouldn't be as effective. He needs to store heat energy for later use and the slab alone doesn't hold as much as the slab plus the sand. So for times like right now (January) where there is no sun light he still has sun energy he can use - the sun energy stored in the sand under his slab.

 

[brogsie]

Because the contractor didn't ask and doesn't know any better. Usually.

Maybe the homeowner takes the lowest price and the quality contractor who has to charge more doesn't get the job. I see it all the time.
People don't have a clue and go with the lowest price. 90% of the new houses built are junk because nobody wants to pay for quality.

 

[DougA]

I did not watch the video but in reading what you are posting I can still say that a lot of the ideas will not work in the far north. My house is an extremely high thermal mass house. Basically, 6" concrete slab with insulation underneath, no basement. We also have the 30' plant wall that is cement block. All of this is used to absorb the passive solar gain during the day - if it is sunny. My experience in real use for 30 years is that thermal mass is highly overrated. If we get a sunny day in the middle of winter, our great room (1000 sq ft but 15,000 cu ft.) is very nice and warm all afternoon but the stove goes back on by late afternoon or it's cold real fast. Keep in mind that my guess is that about 1/3 of our daylight hours are sunny in the winter - at the very max. In the winter, the sun has enough energy at my latitude (43*) to provide enough heat to heat the great room but not enough that there is any storage in the thermal mass worth squat. Fairbanks in close to 65*. There is significantly less energy available and 'next to zero' energy and only 4 hrs. of light at it's shortest. That only leaves about 1 hr. (according to internet search I did) that is barely useful, compared to my 6 hrs. of half useful. Sorry the math does not work for solar gain in the winter at all. Adding sand underneath a 6" slab to provide additional thermal mass sounds exactly like an academic who has no experience getting their hands dirty. If you would like, I can put a temperature probe on the bottom of my 6" slab and see IF there is ANY heat gain at all at the end of 6 hrs. of sunshine. I'll put 100 bucks down the answer is NO. BTW, I actually installed tubing in my concrete floors in front of my large windows for a hydra system. I never hooked it up because after moving in, I realized it would be worthless. Great theory, doesn't work. Even at my latitude, the thermal high mass floor, with porcelain tile covering, would not get hot enough to heat the water in the pipes. Cozy warm to walk on but that's it, there is no excess. What I get heats the room and it's gone by supper time. Yes, there is residual in the evening but I expected the mass to keep the house 'somewhat' warm after sunset. That did not happen and I was wrong. I believed too many experts.

If I wanted to heat a house with half a light bulb, I could do that too but would someone want to live in it? A human requires enough fresh air exchanged to be able to survive and a fan on a heat exchanger alone uses more power than half a light bulb. Solar water panels - in winter??? Really?? I bought and installed commercial grade solar water panels (approx. 72 sq ft. total) so that i could heat up our swimming pool in the hot summer months. Yes, it provides boiling water on a sunny day if you turn the water volume down so it sounds great but our pool was gaining about 5* added temps. The pool never reached a temp feel it was warm enough for me to swim in. I like warm pools and the only way i could ever achieve that was with a combustion water heater. Solar could not do it. The kids loved it but the gain was so little, I sold the solar panels.

High mass walls being better insulation? No. Will high mass walls slow heat dissipation, yes. Two different animals. "although they have the same R values heat passes through them differently." YES, agreed. "Yes its an advantage, because it means less energy going into the wall to replace the heat lost" NO, not if you have tested the R values correctly. Energy will migrate into a higher density wall than a low density wall. That's why low density materials are used for insulation - because dead air is the best insulation. The infamous heat tiles on the space shuttle were ceramic encapsulating billions of pockets of dead air. A higher density wall attracts heat, it wants to absorb it. The opposite of what the author is saying. That means that it robs the house of heat. To say that it retains it for later use is only partially true, some of it will dissipate outside, unavoidable.

ByQ, in short, I'm not trying to be antagonistic to you. It sort of sounds like it but I am more than willing to discuss (challenge) these assertions from 30 years of real world experience living in a house that was designed to be as energy efficient (at the time) as was realistically possible. I spent many years going through the smoke and mirrors of BS that spews out from people with great new ideas. The question I always ask is this, "have you built one and are you living in it now?" Lots of people live to get gov't grants to research new ideas. I think this guy is one of them. It reminds me of all the new discoveries they make in medicine that always seems to come with this line "this looks very promising but we'll need another 10 years of research and studies before it is available"

Dunno, just my 2 cents but I appreciate the discussion. your comments?

BTW, my son-in-law works for a house builder. His sole, full time job is to fix all the cr*p that the contractors screwed up. Every contractor they have tries to cut corners every chance they get. They were pouring foundations when it was below zero F. No covering, no straw bales, no heaters. By Spring the foundation will be cracked. I'm sure there are plenty of good contractors, just not too many in our area.

 

[brogsie]

"BTW, my son-in-law works for a house builder. His sole, full time job is to fix all the cr*p that the contractors screwed up. Every contractor they have tries to cut corners every chance they get. They were pouring foundations when it was below zero F. No covering, no straw bales, no heaters. By Spring the foundation will be cracked. I'm sure there are plenty of good contractors, just not too many in our area."

I bet the house builder hired the low bidder to do the foundation work. The guy that figured to protect the foundation from freezing was probably sitting at home on top of his expensive hay bales.

 

[DougA]

Exactly, around here, it's a race to the bottom and quality be dam*ed. Clearly, people see houses now as they see cars or cell phones, "I'll only own it for a few years and move on"
'Quality is number last'

 

[byQ]

DougA,

It's to late they are working right now, 15 of them - so I guess ya they can work since they do. They may not be all the way down to superhaus level but they are pretty close. I believe his house is the farthest north net-zero house now that he has his PV arrays in. He is a German. He is obtaining a lot of information through gatherings in his country of birth - Superhaus meetings? Anyways, although we in North America started the passive/energy efficient movement the Europeans (especially the Germans) have stuck with it and are now 10 to 15 years ahead of us in their technologies.

His house is only 1500 sq ft, I believe. He is using r-40 thermal shutters for all windows - so heat in, shutters closed, and very little heat out. He admits that without the thermal shutters his system wouldn't work. There is no solar gain this time of year. He has to burn firewood in a masonry heater to get by (1.5-2 cords). And there are coils in the masonry heater to heat water that goes into the tank. Are you south facing? Are you using thermal shutters? Are you running 120 F water through the slab? Are your walls 2 feet thick? Your great room probably has more cubic feet than his whole house.

He has an HRV system from Europe. So the air is fresh. I saw what he is calling an HRV. It is completely different than what we know as an HRV. This thing was geothermal with tubing running underground - thus using the 40 F ground instead of the -20 F air outside - those Germans, wow.

Yes a density wall wants to absorb more heat but once it is saturated it holds the heat longer (just like a masonry heater). He has little children running around in his house barefoot. There must be several differences between your house and his house (?).

 

[Floydian]

A great read on the minimal benefits of interior thermal mass in cold climates here: http://www.greenbuildingadvisor.com/blogs/dept/musings/all-about-thermal-mass

I saw what he is calling an HRV. It is completely different than what we know as an HRV.

It is also far more expensive than than some of the NA options. Yeah, its more efficient but were only talking about a few % better at best. Great if the budget allows, not so much for the avg home owner.

Noah

 

[DougA]

First, I need to correct something I posted earlier. "about 1/3 of our daylight hours are sunny in the winter - at the very max." That is true but then I used that to interpolate the usage energy from the sun in Fairbanks. In fact, during Dec & Jan, when we need the heat the most, 33% might be sunny days but of that, very little of it is USABLE sunlight with enough energy to warm, let alone heat, our room. If the entire day is sunny from 8 am to 5 pm, the sun is high enough and strong enough to provide heat from 11 until 2. That works out to one third of the sunny hours. So if 33% of the time we have sunshine and only 33% of that is useful sunlight at our latitude, we are only getting 1/9 of the daylight hours as useful sunlight. In Fairbanks, that probably means zero useful hours. Even in the Spring and Fall, Fairbanks would be pretty questionable for heat gain. So, all that for 3 or 4 months of heat gain when it's already warm outside. Just stupid. You can't take the heat gain in the summer and store it to heat your house in the winter. Impossible.

Floydian, finally got to read your link and I agree with everything that the author is saying.
“The mass effect is real,” Alex Wilson wrote. “High-mass walls really can significantly outperform low-mass walls of comparable steady-state R-value — i.e., they can achieve a higher ‘mass-enhanced R-value.’ But (and this is an important “but”) this mass-enhanced R-value is only significant when the outdoor temperatures cycle above and below indoor temperatures within a 24-hour period.” This quote says most of it. In my case, I am positive we lose a ton of heat in winter through our massive south facing windows at night and when it's cloudy. The upside is that it provides us with a great room that opens up to our entire property to live in without going outside. There is no dollar value that can be placed on being able to sit here right now gazing out on acres of trees and wildlife. We understood the benefits and pitfalls when we designed and built the house. Mass is a benefit when we get a lot of sun from Oct. to April and helps keep the house a bit more cool and regulated in the summer. As the author stated, a correctly designed overhang is the key component of passive solar success. The real benefit of thermal mass is in temperature neutral areas when heat during the daytime can be used to heat the building in the night and vice versa.

One thought to relate this to Fairbanks is actually using opposing seasons. Our mass helps regulate the extreme heat of the summer HOWEVER, if we get more than 3 days of high temps (both day & night), the thermal mass is actually a problem. All that heat is retained by the mass and if it can't be cooled off by open windows at night, the house is too hot without a/c. The thermal mass is working against you in that situation, just as Martin Holladay writes. So, translate that to Fairbanks in winter. There is no solar in winter to heat the mass, so it retains the cold and you end up spending money to heat a thermal mass to keep the house comfortable. Heating the mass is expending extra energy that is not needed. Thermal mass in cold climates actually works the opposite of a radiant wood stove. Concrete at room temperature feels cool and draws heat away from everything.

To get back to Fairbanks, I love one more quote from Holladay, "Even though interior concrete sometimes has thermal benefits, it also has drawbacks — including its high cost. In most climates, you can get the same benefit that concrete might provide by simply installing more insulation — and in most cases, the added insulation will cost less than the concrete.
Remember: the better insulated your house, the less thermal mass matters."

I have tried to spend time to view the video of the Fairbanks presentation but it's a total of 4 1/2 hrs. OUCH. I will try again tonight and tomorrow but It's tough going when I disagree with what he is saying.

To answer some of your last post:
If he's using geothermal, that is not net-neutral energy. It's a heat pump using ground water for the source of heat. There's absolutely nothing new about that. I looked at it 30 yrs. ago when I built and the only difference is that heat pumps are now more efficient than 30 years ago. I decided not to go that route due to the extremely high cost. The payback at that time was nearly 2 decades and it was far better to spend money on other energy efficiencies. There is nothing special about German ingenuity on ground source heat pump either.

The size of the house is not a big deal. It just costs more (obviously). Actually, our's works better than most because our great room contains so much air volume. The important factor is in the shape of the outside and how the interior is designed to take advantage of areas (such as bedrooms) that are normally wanting to be cooler during sleep and kitchen/living areas that need to be warmer when occupied. Also, air flow makes a big impact on the 'feeling' of warmth. We rarely feel any draft or air movement in our great room which means it can be a few degrees cooler and still feel identical to a warmer room with an air flow. A house that is boxed shape is much more efficient to insulate and to heat/cool than a spread out ranch style. The problem is that in North America, we like spread out designs these days. Houses built 60 yrs ago were much better designed for efficiency than now, even though they were poorly insulated. I agree that Germans/Europeans are more practical and farther ahead than us in their design thinking. North Americans are much too consumer/'I want' attitude in their thinking. It's going to be very hard to change that. Part of that is our entire culture. I've been to most countries in Europe and our entire way of living is so different. Public transit, small living spaces, etc. are not going to be accepted here any time soon. Even the houses in Fairbanks could not be built in my region where a minimum 2K sq ft is required by law. Most new houses near me are 5K and some are way over that. Just insane.

We have a wood stove and are planning on changing to a masonry heater this summer, mostly because our wood stove and chimney are now 30 yrs. old and reaching their life expectancy. Once again, a masonry heater is a significant source of energy but very costly to operate unless you have access to free firewood. If everyone in the US installed masonry heaters, we would exhaust the wood supply very quickly. It certainly is a renewable source of energy but 30+ years to renew is not insignificant plus the air quality problems if millions of people burned wood. From all my research so far, preheating water with a masonry heater is not efficient. I will look into this further because I have the water hook-up near where the heater will be but I doubt it's worth it. A tankless water heater is far more efficient BUT as I posted elsewhere on this forum, the selling price for tankless is astronomic by comparison.

Yes, our house faces south exactly. No, no thermal shutters. Our top windows are trapezoids and I spent years trying to figure out how to make thermal shutters work effectively. When I was researching it back then, most people with thermal shutters were not using them nearly as often as they planned on. They were too lazy. Yup, I think the truth is hard to believe but why spend so much money and not use them? It's not as simple as pulling a curtain and it takes effort, something most people won't do after a few years. That is the base problem on many energy efficient changes.

My walls are about 12" thick. Double wall construction in this order, from out to in: stucco or wood exterior, 1" thermal cladding, 2x6 vertical studs on 24" centres, triple thick vapour barrier, 1x3" horiz. studs on 24" centres, drywall. Keep in mind that some things that are in use now were not allowed in the building code 30 yrs ago. I do not run hot water through my slab. As the link Floydian posted, it refutes most of that idea and although I installed the tubing, it was never hooked up. That whole idea is so wrong on so many levels it's honestly not worth discussing.

I promise to try to view more of the video tonight, after I have some rum in me to get me in a more receptive mood.

Doug

 

[byQ]

Those videos are hard to view completely. The speaker does a lot of graphs relating to the water tank. I also read that minimal effects of thermal mass Floydian posted. It makes sense that heavy thermal mass walls would work best in certain places where the outer temperature rises above and drops below the internal temp of the house. The heat is absorbed during the day and than when the sun goes down it continues to heat the insides. By morning the wall has cooled and when the outer temp goes up the wall is there to absorb more heat.

He seemed to be for thermal mass in the case of passive solar construction - but not for it in other cases. And, the author has no awareness of thermal shutters. There's a huge difference between R5 and R40.

And I believe you could use summer and fall sun to heat during the winter. You would have to have a very large thermal mass to do it. If you had 8 feet of sand under the floor slab (well insulated) that you started dumping heat into starting in say July you could go for quite a while once there was no sun later in the year. On a 50' x 40' house this would be 16,000 ft3 of hot sand. You'ld probably still need some other form of heat in the spring.

Combine the sand with a 2,000 gallon water tank and you are accumulating a lot of heated mass. The solar water panels combined with a small super insulated house with hydronic heating seems like a great set up, even if there isn't good sun all year long. Once it is in place and working there isn't much energy being used to make it go - just pumps.

How can solar hot water systems hooked to a tank, a pump, and pex tubing in the slab not be good? What a simple system. You are just transporting the sun's energy into water and than transporting the water into your structure where that energy is dropped off. Sounds like almost free energy to me.

If I get around to building a masonry heater I'm not going to put water coils in it, either. Most of the masons have said this is not a very good idea.

 

[DougA]

And I believe you could use summer and fall sun to heat during the winter. You would have to have a very large thermal mass to do it. If you had 8 feet of sand under the floor slab (well insulated) that you started dumping heat into starting in say July you could go for quite a while once there was no sun later in the year. On a 50' x 40' house this would be 16,000 ft3 of hot sand. You'ld probably still need some other form of heat in the spring.

That is just plain not correct. You are free to do what you want but I would strongly urge you to have an engineer who is trained in this to correct you since I doubt you will believe me. My personal opinion is that the thermal mass will last days at most, not months. Sand is not a great way to store heat. In fact, I had never heard of it until this discussion. Many people used to try rocks, which are far cheaper since they are more readily available. Water makes a great storage medium but the container to keep a huge amount of water in is very pricey.

Combine the sand with a 2,000 gallon water tank and you are accumulating a lot of heated mass. The solar water panels combined with a small super insulated house with hydronic heating seems like a great set up, even if there isn't good sun all year long. Once it is in place and working there isn't much energy being used to make it go - just pumps.

I think you have bought into his BS. It won't work nearly as well as you think and it is very expensive. There are so many better ways to spend your money.

How can solar hot water systems hooked to a tank, a pump, and pex tubing in the slab not be good? What a simple system. You are just transporting the sun's energy into water and than transporting the water into your structure where that energy is dropped off. Sounds like almost free energy to me.

The theory is good. Warm floors are wonderful but not an efficient or cheap way to heat a house. The solar panels will not collect enough energy to make it work the way you envision.
I have a brother-in-law who took advantage of a gov't grant to cover his 4,000 sq ft ranch house with solar panels. The gov't pays him $.82/KW/hr to do this, even though the cost of wholesale power in our province is about $.04/KW/hr. It's the only way the solar panels could become economically viable. Even with his entire south facing roof covered (at a cost of $75K), the panels do not provide enough power to provide 100% of the electrical needs of his own house. He knows that but the grant was too good to pass up and after 15 yrs., he will realize a profit. Unless of course, either the gov't renegs on the contract (the gov't is close to falling over their energy policy) or when he has to pay the contractor to remove and re-install his panels when he has to re-shingle his house. That will just about equal the profit on the 5 yrs. left of his 20 yr. contract. In short, unless the gov't HEAVILY subsidizes solar panels as they did in our area and as they did in Germany and Spain, they don't pay their cost. At least until better technology is invented. I'm all for solar panels but not when the taxpayer has to fork out $75K for one house to make it worthwhile.

I sat through more of the video and I stopped at this sentence. Paraphrased - He has built a zero energy, carbon neutral house that uses no fossil fuels and only a masonry heater (a few cords) as a backup. This guy is both a liar and a complete idiot. I have no interest in seeing any more. It's a waste of my time.

I don't think I will change your mind and I have no interest in getting frustrated watching videos of a slick salesman selling snake oil. Truly, I wish you luck. You will need it.

 

[byQ]

Bless the people who are willing to try new things so the rest of us (at least those of us that aren't too close-minded) can learn and maybe try new things. This woman's experimental house (in 1995) is using a sand basement with pex tubing towards the bottom of the sand and also in the slab (independently heated). The insulation around the basement full of sand is low - 4" rigid board in walls and 2" rigid board in floor .

They start charging this mass in August, stop in December (not enough sun), and than make it until January before they need to send hot water through the slab again via some other energy source. So they make it a month or so, not days, but not several months either. They aren't using R-40 thermal shutters on all of that south facing glass nor much insulation around the sand. However, they aren't in Faribanks, Alaska, either (appears to be middle America somewhere).


Note: they have a $15,000 masonry heater. There is a 1.5" gap between the masonry heater's core and outer shell. This seems to be excessive - 1/4" more common.

 

[DougA]

I have been thinking about a larger gap between the core and the outer stone shell/facing. 1/4" does not make sense to me but it is to allow expansion/contraction of the refractory bricks without damaging the stone/brink facing. I was thinking that if you had a bigger gap, you could have air flowing through and generating more heat quickly, than if the heat has to penetrate both the refractory brick plus the stone/brick facing. Having to wait so long for a masonry heater to warm a room is a bad thing but the idea is that once going, the heater should be on all winter. If the gap is too large, the heat will not penetrate to the facing and you'll lose the benefit of thermal mass. I'll be discussing this with a few people who have a lot of experience with masonry heaters. Some of the very best in N. America live close to me. I have a feeling they will set me straight.

I do not think I am closed minded at all. I think I am a realist. When I was building my house there was no internet but Mother Earth News took it's place. It was full of information but a great deal of it was mis-information. Great that people try new ideas but each of us has to carefully sift through and determine which ones are over glorified, which are mostly BS and which are complete junk. The internet is full of complete junk and BS and finding the truth today is harder than it was 30 yrs ago.

Before you put a shovel in the ground, invest some money in a plane ticket to see the places you are looking at and interview the people and also interview the detractors. Only then will you have a complete picture. What you do is your business. I'm just trying to help you not make a costly mistake. BTW, 2" of rigid foam, then tons and toms of sand and concrete on top is a huge mistake. Two inches is not nearly enough and the foam will compress and deteriorate over years, making the thermal mass less useful each year.

Also keep in mind that rodents love to burrow in foam. I installed fibreglass insulation due to that very fact. I was told that rodents would not burrow in fibreglass because the glass fibres are so scratchy. The experts were wrong about that too. Mice and rats love to tunnel and make homes in fibreglass just as much as foam. I was reading an interesting blog you might want to see. A rat can easily chew through mortar or wire if it wants to and that's all that's stopping his home from being overrun. Mice and bats can go through tiny air vents in ducts and masonry. I would have bet any money it was impossible until I saw it for myself. He built a masonry heater himself and has some good ideas and some I would not use. Anyway, here is the link:
http://jaredbarnhart.blogspot.ca/

 

[GaryGary]

Bless the people who are willing to try new things so the rest of us (at least those of us that aren't too close-minded) can learn and maybe try new things. This woman's experimental house (in 1995) is using a sand basement with pex tubing towards the bottom of the sand and also in the slab (independently heated). The insulation around the basement full of sand is low - 4" rigid board in walls and 2" rigid board in floor .

They start charging this mass in August, stop in December (not enough sun), and than make it until January before they need to send hot water through the slab again via some other energy source. So they make it a month or so, not days, but not several months either. They aren't using R-40 thermal shutters on all of that south facing glass nor much insulation around the sand. However, they aren't in Faribanks, Alaska, either (appears to be middle America somewhere).


Note: they have a $15,000 masonry heater. There is a 1.5" gap between the masonry heater's core and outer shell. This seems to be excessive - 1/4" more common.

That is a terrific video -- thanks very much.

Is there a website that the video came from? Or, anymore information on David Anderson the builder?
I'd particularly like to get the data he collected from the temperature sensors that were embedded in the sand stack.

I've had a strong interest in this sand bed storage and collected all I could find on it here, including several example homes and a bit of analysis on how much seasonal storage one might expect out of a sandbed: http://www.builditsolar.com/Projects/SolarHomes/constructionps.htm#Sandbed

To me, this is the most successful seasonal heat sandbed storage home I've seen, and I think the reason is the depth of the sandbed. Most of them are built with sandbeds that are 2 or 3 feet deep, and they just can't put away enough heat heat in the late summer and fall to make a whole lot of difference in the winter. This house does pretty well in this regard.

One thing I am curious about is how much of the heat that is stored in the deep sandbed ends up getting to the house vs how much is lost out the bottom of the sandbed and the walls of the sandbed. The walls and bottom are insulated, and that should help more of the heat go in the intended direction, but, it would be nice to know how successful the design is in this regard.

I agree that we owe a great deal to people who are willing to take a promising concept and put the money and effort into doing a prototype -- hope to be one of them on our next house.

Gary

 

[DougA]

Did a bit more research which means clicked Google and then the first link that came from an academic source. The link is here:
http://web.ornl.gov/sci/buildings/2012/1985 B3 papers/098.pdf

The quick facts are:
Town hall bldg. in Volney, NY. This interested me because it lies in almost the identical latitude as I am so whatever works there, would work for me. This is a building constructed at the height of the oil crisis and specifically designed to take advantage of every energy savings feature available at the time. In short, it was an experiment paid for by taxpayers.
Yes, larger structure than a house but super insulated with 710 sq ft of south facing solar collection surface. That is equal to 10' x 71' and must be massive.
39,744 cu ft. sand mass in addition to a substantial cement mass and R35 insulation in the ground. That is an unbelievable amount.

The test period was from Feb 23 to March 2, so the test period is 3 weeks prior to the Spring Equinox, not the dead of winter by any means. In fact, as I sit here this afternoon, my south facing solar windows have risen my home to 80* with zero aux. heat but it is 4* outside. That's amazing.
They turned the aux. heat off on Feb. 23 and relied 100% on the heat produced by solar gain and stored in the sand/cement mass. Feb. 25, 26, 27 were very sunny, resulting in max. solar gain with 2 other days being partial sun.

The building went from 70* on Feb. 23rd down to 62* on Feb. 28th, even though most of those were sunny days. On Feb 28th, they turned the aux. heat back on (due to it being too cold to work inside). So, even with an enormous solar panel area, ideal sun conditions, ideal time of the year for solar gain vs. cold weather, super insulation and an enormous mass of sand and concrete, the bldg could not heat itself using solar with sand/concrete mass combination.

Yes, I am positive all of this helps lower the heating costs and I am positive that the bldg is substantially better off in summer with less cost for cooling but it still cannot attain net anywhere close to net zero energy. If it can't do it at this temperate latitude, how is it possible in Fairbanks AK? I do not comprehend.

Please find me a link to a home or bldg. that doesn't look like a dead turkey with a sand mass that has 'net zero' (or even close) energy requirements that has been scientifically analysed by independent, academic researchers and I will eat my words.

 

[efred]

"BTW, my son-in-law works for a house builder. His sole, full time job is to fix all the cr*p that the contractors screwed up. Every contractor they have tries to cut corners every chance they get. They were pouring foundations when it was below zero F. No covering, no straw bales, no heaters. By Spring the foundation will be cracked. I'm sure there are plenty of good contractors, just not too many in our area."

I bet the house builder hired the low bidder to do the foundation work. The guy that figured to protect the foundation from freezing was probably sitting at home on top of his expensive hay bales.

I know what you mean. It's a shame that most contractors these days seem to want to just get stuff done as fast as possible so they can move onto the next job.

In the end it takes them longer as they have to go back and fix their mistakes.

I think we're really on the cutting edge of creating energy efficient homes right now though with all the technology that we have and the tech being built.

A pretty cool time for house builders.

 

[iamlucky13]

Windows that should be located more in than out for 20% savings. OK, but a good low-e double insulated window is between R2 & R3, whereas a good wall would be at least R24. So, if you save 20% of R2, your savings is squat. Good curtains are far better.

I agree with most of what you've said in this thread, but if I'm understanding your argument on this specific point, I don't quite agree. I can't verify his 20% claim, and it almost certainly declines the larger the window since I presume the effect is mainly convective, but if true, it's a non-trivial savings.

With an R2 window, you're seeing 12 times as much heat conducted out the window as an equivalent size area of R24 wall.

For a moderately large 10 square feet window and a 35 F temperature difference, that's 175 BTU/hour for that single window (~50 Watts). For the adjacent wall, it's 15 BTU/hour (~4 Watts).

Add 20% (or worse, add 20% only to the window and the same numerical R-value increase for the wall) so you're up to R2.4 and R28.8. Now the conductive heat loss is 146 BTU for the window and 12 BTU for the wall. You cut heat loss by 29 BTU/hour for the window, but only 3 BTU/hour for the same amount of wall area.

You should add curtains, too, but if you're building new or a complete gut and remodel and have the opportunity to inset the windows (and somebody can verify his claim that insetting the windows reduces heat loss), then you can do both insetting and adding curtains.

Of course, there's more wall area than windows, but further improving the walls beyond R24 isn't going to be easy. The main lesson here is the well-known advice to prioritize the low hanging fruit when you look for energy improvements. Insetting windows isn't quite low hanging fruit, but it's a lot easier than digging a huge foundation out to fill with sand to create a geothermal system with moderate advantages over one in your yard.

I didn't watch the videos, but from the other comments here, it sounds like that is what he's doing - using solar thermal during the summer and perhaps to a degree in the winter daytime to increase the temperature of the thermal mass his geothermal system draws on above the average deep soil temperature. I can see some benefits to doing so compared to an ordinary geothermal system, but a lot of investment to get there.