Creating Mass - Density?

[Teken]

Back Ground: During the course of building my home five years ago I wanted to build the most efficient home I could based on my current budget and finances. To that end my goal was to follow and mimic as many elements from passive homes / NET neutral homes.

 

The ultimate goal was to reduce my over all energy costs in areas of electricity, natural gas, and water consumption.

 

During the last five years I have been incorporating many elements of Home Automation (HA) which has provided me a wealth of technical data and the means of controlling my homes environmental's.

 

I am currently on an impasse where I am trying to create more mass / density. The reason for this is some key areas I was not able to use the tried and true method of mass / density because of design consideration and over all costs.

 

Which was to pour a solid concrete slab in the south facing side of the home. This simple yet effective technique allows the home to consume and bask in the daylight. This at a later time will slowly release the stored heat energy back in to the home via radiated heat.

 

So, the question I have for those familiar or have ideas for a guy who wants to accomplish a similar goal is how to create mass / density on a KD budget. Yet also be easy to install and retro fit into an existing homes floor?

 

As I am sure many of you are aware mass does not always equate to density. Also, sometimes the density does not equate to the same ability to store and release said heat energy?

 

What are some of the novel ideas this smart community has to offer me??

[larryllix]

Water is classically the best to work with, move, store, has high thermal mass, and a cheap price.

 

Years back I heard stories of a homeowner installing many 2" abs drain pipe runs full of water in basement ceiling to do this.

 

Decorator brick wall across from solar gain windows are common.

 

Attic runs of PEX piping can be done to accumulate heat but boiling, freezing, and pressure problems can be paramount. Antifreeze has it's own problems.

 

A few have used semi-passive air flow solar gain wall cavities although I think this is not very workable in a home in Canuckistan. Perhaps in the southern half of the US or in northern parts, an out building though.

 

A swimming pool and a spare heat pump can make some interesting ideas.

[Teken]

Yeah, I had entertained doing the water wall before as a possible solution. But the reality is there was no 100% guarantee I could install it in a way that would pass my UL certification. There are some gel packs which I have looked at which can be either heated or frozen.

 

They would allow me to have something a little more stable and self contained. The idea was to place these gel packs into a custom enclosed frame of sorts. The out side frame could be toggled from a dark custom image for the winter months to attract the solar heat and in the evening slowly radiate that heat back into the room.

 

During the summer the same picture frame would be inverted like blinds with a lighter custom image to reflect the heat as much as possible. In the summer time all of the windows would be open to let the space cool down. The same picture frame wall unit would thus be cooler and radiate its cool temps back into the living space.

 

Since heating is more prevalent in my region which is 7 months out of the year. The heating element would be the primary goal for this endeavor.

[larryllix]

Usually well designed window awnings to let radiant solar energy in, in the winter and keep it out in the summer is the best passive system to use.

 

People claim trees work well but logic dictates they don't. The only shade underneath themselves when the sun is high unless they are growing on your roof.

 

Years back people mentioned attempting to engineer the use of waxes that change phase under human temperatures and can retain massive amounts of heat energy.

[Teken]

True, but my goal is not only to let the sun in but to store that heat energy and release it slowly back into the living space. Windows in themselves will not accomplish this end goal.

[larryllix]

True, but my goal is not only to let the sun in but to store that heat energy and release it slowly back into the living space. Windows in themselves will not accomplish this end goal.

Same thing would apply except you need the windows to hit onto some thermal mass to slow it down.

 

Over the years I have seen more people build "Florida rooms" only to find themselves over heated and buying heat repelling blinds. People have no idea how much of the sun's heat is radiant....all of it.

[Teken]

Same thing would apply except you need the windows to hit onto some thermal mass to slow it down.

 

Over the years I have seen more people build "Florida rooms" only to find themselves over heated and buying heat repelling blinds. People have no idea how much of the sun's heat is radiant....all of it.

If I could do a sun room I would in a heart beat. But need to work in the limits of the current building structure and modify the best I can to the existing structure and decor. ️

 

I will need to look into alternative methods to build the thermal wall and floor.

 

 

Ideals are peaceful - History is violent

[builderb]

And here I thought this would be a discussion of theoretical physics!

 

Be careful adding mass to an existing structure, particularly up high. Unless your structural system was designed to accommodate it, you risk settlement, deformation, and, in extreme cases, structural damage.

 

I've never done this myself, but I have heard of people using a rock bed in a crawl space under the house to store heat. I toyed with the idea of laying CMU blocks next to each other sideways to create horizontal tunnels that you could blow hot air through during the day, but never got past the drawing board stage. I still think there's potential there though.

 

Larry's suggestion about window shading is spot-on too. If you do it right, the sun hits your mass between say September 21 and March 21, and doesn't hit it outside those dates.

 

 

Sent from my iPad using Tapatalk

[Teken]

Be careful adding mass to an existing structure, particularly up high. Unless your structural system was designed to accommodate it, you risk settlement, deformation, and, in extreme cases, structural damage.

 

I've never done this myself, but I have heard of people using a rock bed in a crawl space under the house to store heat. I toyed with the idea of laying CMU blocks next to each other sideways to create horizontal tunnels that you could blow hot air through during the day, but never got past the drawing board stage. I still think there's potential there though.

 

Larry's suggestion about window shading is spot-on too. If you do it right, the sun hits your mass between say September 21 and March 21, and doesn't hit it outside those dates.

 

 

Sent from my iPad using Tapatalk

Understood about taking into consideration of weight and structural integrity. I have a great south facing kitchen and master bedroom.

 

My goal is to maximize the heat absorption and the rate in which this energy is released back into the home during the evenings. I am still considering perhaps some concrete boards used for bathrooms but layered and cut to a design which can be fastened to the walls. To the average person it would appear like trim or art work.

 

The reality is it would serve as my solar wall. If I combine this with the gel I might be able to retain more hot / cold.

 

 

Ideals are peaceful - History is violent

[builderb]

Adobes in the southwest were designed with walls thick enough that they weren't saturated with heat until late in the day,. This has the complimentary benefit that because of this high amount of mass, it stored enough that it would radiate heat most of the night.

 

With such thin material as Durock (or similar), I would be concerned that you would saturate it quickly, and that it would give off its heat just as quickly once the source heat wasn't available. Once saturated, it will heat things around it, so if this is occurring during the day, it's adding to your heat load (you're in The Cold, so not sure you care about this, but it would be a definite problem for me), and subsequently not doing much for you into the night.

 

There are issues with heat transfer, too. Heat radiating from one wall won't make it far without help. If your HVAC system is already moving air, then you're probably fine within individual south-facing rooms, but you won't see much benefit in other spaces. Otherwise, you'll get some convection action, but not much.

 

Reaching back to my sustainability classes, the reason you use water for thermal storage is because it's something like 3 times as efficient at thermal storage per cubic foot as concrete. The reason you use concrete for thermal storage is either because volume isn't an issue, or because you can heat concrete to far higher temperatures than water, thus making it more efficient than water by volume.

 

You've got a bunch of 1-wire temp sensors though. Build a little insulated box with a couple of layers of cement board on one side, put it in the sun, then monitor the temp inside versus outside. That should give you a ballpark idea of what you could expect in terms of time to saturation and time to depletion.

 

 

Sent from my iPad using Tapatalk

[Teken]

Adobes in the southwest were designed with walls thick enough that they weren't saturated with heat until late in the day,. This has the complimentary benefit that because of this high amount of mass, it stored enough that it would radiate heat most of the night.

 

With such thin material as Durock (or similar), I would be concerned that you would saturate it quickly, and that it would give off its heat just as quickly once the source heat wasn't available. Once saturated, it will heat things around it, so if this is occurring during the day, it's adding to your heat load (you're in The Cold, so not sure you care about this, but it would be a definite problem for me), and subsequently not doing much for you into the night.

 

There are issues with heat transfer, too. Heat radiating from one wall won't make it far without help. If your HVAC system is already moving air, then you're probably fine within individual south-facing rooms, but you won't see much benefit in other spaces. Otherwise, you'll get some convection action, but not much.

 

Reaching back to my sustainability classes, the reason you use water for thermal storage is because it's something like 3 times as efficient at thermal storage per cubic foot as concrete. The reason you use concrete for thermal storage is either because volume isn't an issue, or because you can heat concrete to far higher temperatures than water, thus making it more efficient than water by volume.

 

You've got a bunch of 1-wire temp sensors though. Build a little insulated box with a couple of layers of cement board on one side, put it in the sun, then monitor the temp inside versus outside. That should give you a ballpark idea of what you could expect in terms of time to saturation and time to depletion.

 

 

Sent from my iPad using Tapatalk

 

Your feed back is invaluable to me and I thank you for providing such details! You're correct using the durarock board in itself will not hold enough heat for a prolonged period of time. I highly doubt it would be able to release much energy past 1-2 hours. This is why I have considered using some kind of hybrid wall / floor system.

 

For the wall it would be a combination durarock, gel, and perhaps a medium CFM fan to help move the air around. Right now I am in the middle of finishing up the last few ceiling fans to help circulate and move as much trapped hot air in the ceiling and vaulted ceilings in the living room and kitchen areas.

 

Like most family's we spend much more time in the kitchen, bedrooms, and basement. Well, besides the girls in the washroom for hours on end painting their faces!

 

I believe you're also correct a small scale model will help prove out the initial design concept before investing more money for very little gain.

 

As always I thank you and each of you for your time and input.

[builderb]

No problem. On a semi-related topic, some day I'm going to build one of these for fun, and see how well it works. Although in my climate, I think I'd use it on an east-facing room for morning heating. It's not often we get lots of sun while it's still cold, so harvesting late-day sun only really helps me in the coldest part of winter, and would be unbearable in the summer.

 

http://faircompanies.com/blogs/view/building-a-solar-heater-with-recycled-cans/

 

 

Sent from my iPad using Tapatalk

[Teken]

No problem. On a semi-related topic, some day I'm going to build one of these for fun, and see how well it works. Although in my climate, I think I'd use it on an east-facing room for morning heating. It's not often we get lots of sun while it's still cold, so harvesting late-day sun only really helps me in the coldest part of winter, and would be unbearable in the summer.

 

http://faircompanies.com/blogs/view/building-a-solar-heater-with-recycled-cans/

 

 

Sent from my iPad using Tapatalk

 

Yes, I have toyed with the idea of doing this same kind of project for many years. But, alas I could not bring myself to mount such a kludge on to my homes exterior wall.

 

We have a credit union which did an excellent solar wall but it was integrated into the exterior facade and the average person can not tell or even knows it serves a secondary purpose! Maybe if I win the Lotto next week I will do some kind of reno where I can redo two of the south facing walls to mimic what they did.

 

Their use was very much what I wanted to do but sadly no one around me will do it or in a budget that makes sense. They use it for heating, and heating water. If I could have done the same it would have killed two birds with one stone.

 

As the next top energy hog is my HWT which every month is just killing me! 

[larryllix]

Thermal mass techniques don't work hat well in Canada year 'round. Mostly spring and fall only where temperature averaging has an energy saving benefit. I remember a Usenet discussion recommending the technique but that summer we never had one night below 23 c for the whole summer. Of course that was a non-typical year.

 

Building a false wall in front of  your thermal mass solar radiant absorber could work. Alternating short studs could make a maze style long air pocket to move the heat way from the wall to the far and colder end of the home. A similar technique could be done with 1-2" abs piping or smaller PEX filled with water and ISY controlled logic to distribute or store some of the heat via switched fan radiating setups or even returning stored hot water to the same wall. If one had a creative enough flair and acceptance a spiral abs/pvc pipe décor pinned to the heavy wall surface as a collector/radiator. All painted as a modern art creation. PEX pipe could be worked into the mortar of a decorative brick façade wall surface also. Some sort of pan for water leaks would need to installed into the design for the odd chance of failure. Air only systems may be easier in that aspect.

 

Creating a rad out of an old box fan cabinet by spiralling pex between two steel spoked arrangements could work with a second box fan. ISY controlled, of course.

 

One of the simplest systems uses a small solar PV panel to drive a Grundfos water pump so that when the sun shines the conducting fluid moves. This doesn't remove latent heat from a brick high thermal mass wall though. I can imagine a wall using some heavy board, with a modern art zigzag piping glued to it, as a modern art piece, painted a dark absorbent colour with a solar PV panel framed as a  circ. pump taking the heat to the other end of the house with a 12vdc fan running off the PV panel distributing the heat into a cold far corner of the basement. This could also be an enclosed box of bricks that drags the heat dispersement out over the next 12-15 hours. This could also be a ceramic bathroom floor in the basement with an embedded PEX grid. Always run your in floor PEX in a double spiral. Spiral from outside to centre and then double back and spiral back. Coldest end is always mixed in with the warmest end for the most even heating.

 

Just some ideas I have discovered in my travels installing energy systems.

[Teken]

This was the solar water (brick) wall that I reviewed quite a number of years ago. Unfortunately I was never able to determine who the maker was and what the costs were.

 

I have booked marked this video for (hopefully) in my journey that this is something I can do down the line. Perhaps this will help out someone else who is about to build, reno, etc.

 

This is exactly what builderb was talking about how water stores more BTU's when compared to other media.

 

[larryllix]

Before I built my house with hydronics etc. I did a little solar radiation experiment I should mention as it was dramatic.

 

I used a remote thermostat probe and a 12 inch glass pie plate for this experiment. It was on my south facing deck with some odd 10-20 degrees C below zero (-5 - 10 F) weather each day and bright sunshine probably in mid March one year.

 

1. I place the wireless probe under the upside down pie plate on a white picnic table I had cleared the snow off of. - Next day it read approximately 50 F.

 

2. Same as above. Tipped the pie plate up to the sun's angle more. Next day reads about 60-70 F (these are aproximate)

 

3. Same as above but used a 1" piece of styrofoam under the pie plate to insulate and partially seal out winter air. Tilted toward sun.  Next day high read was abut 90-100 F.

 

4. Same setup as above. Gave the Styrofoam a shot of black lacquer paint. Yeah it melts into the Styrofoam but a light coat works if you are fast. Next day readout. on  the high temp was some garbage that made no sense. Battery died? Went outside to check probe and the readout was dead. Picked the probe up and the plastic case had melted on both sides. The probe was destroyed and the electronics fried. After many attempts with resetting and new batteries I tossed it in the garbage.

 

Impressed? You bet I was. Hydronics may allow me to bring some of that radiant solar heat into my system some day. For slab heating you only need to heat your slab less than half a degree warmer than your room, if even that. The problem with liquid solar thermal collection is boiling water into steam. Anti-freeze is worse for boiling. Shoving liquids up into a preheated solar collector can result in explosions.