Best floor covering for keeping thermal mass

dymonite69 · Dec 27, 2008 11:04 pm

Casa2

I'm happy to have timber flooring over an in-slab hydronic heater.

Sometimes you can have too much of a good thing. This article by the Oregon Dept of Energy in the US issues a warning about heating the same section of slab using both passive solar and hydronic heating simultaneously:

http://www.oregon.gov/ENERGY/CONS/RES/tax/Radiant.shtml

BTW Oregon is what you may consider a cold temperate climate which can be slightly more extreme than Tasmania.

Yak_Chat · Dec 28, 2008 8:54 am

dyno - Seeing as casa is in NSW not TAS - I don't think he will have that an issue with solar heated slab which is both direct sun and solar heated hydronic.
Which is what has been done in the Ada st house in Adelaide.

Casa - on the hydronic system, are you doing a thermo coupled closed loop system to avoid growth of bacteria etc in the lines? Or circulating that water through the panels and running a seperate system for the HWS for domestic use.
I know your using a tank somewhere.
And I agree that warming the wall bricks where there is carpet is best.

Getting back the original post

Archaeobabe
Is you house designed with large norht facing windows to get full sun landing on the majority of the slab to heat it up?

Steve

archaeobabe · Dec 28, 2008 9:10 am

Yak_Chat

Archaeobabe
Is you house designed with large norht facing windows to get full sun landing on the majority of the slab to heat it up?

Steve

It most certainly is, which is why we were thinking that tiles were our only sensible option (exposed slab having been excluded). No hydronic heating unfortunately as we couldn't make our budget stretch that far.

Casa2 · Dec 28, 2008 9:11 am

Yak_Chat

Casa - on the hydronic system, are you doing a thermo coupled closed loop system to avoid growth of bacteria etc in the lines? Or circulating that water through the panels and running a seperate system for the HWS for domestic use.
I know your using a tank somewhere.
And I agree that warming the wall bricks where there is carpet is best.

Steve,

There are two tanks. One for domestic hot water and one for space heating. The domestic hot water tank has booster heating, but the space heating hot water tank has none. That is, if the tank temperature runs down in winter because there's been several cloudy days in a row then the house gets cold (bad luck). The beauty of this is that I will not spent any energy (or money) for heating or cooling (except for running some water pumps, which is a very small power usage).

Now each tank has two loops. The loop to the solar panels is thermosyphon, so no pumps required here. There will be a pump or pumps for the hydronic in-slab loops.

If you're ever in Sydney, I should show you my plans. You'll like them!

Cheers,
Casa

dymonite69 · Dec 28, 2008 10:05 am

Yak_Chat

dyno - Seeing as casa is in NSW not TAS - I don't think he will have that an issue with solar heated slab which is both direct sun and solar heated hydronic.

The concern was overheating due to dual simultaneous inputs from direct sun and hydronic.

Casa2 · Dec 28, 2008 10:10 am

dymonite69

Yak_Chat

dyno - Seeing as casa is in NSW not TAS - I don't think he will have that an issue with solar heated slab which is both direct sun and solar heated hydronic.

The concern was overheating due to dual simultaneous inputs from direct sun and hydronic.

For my house, the direct solar gain and hydronic heating sections are separate. The north side has the direct solar gain (funny about that), while the south side has the hydronic heating. Because the views are to the south, most of the living areas are to the south. So what I've done is captured the northern sun (using 6 solar panels ) and transferred this heat to the south via the hydronic system.

Now, if the house can be oriented in any direction, it's simple. Put the living areas in the north and the bedrooms in the south and you won't need any of this fancy (and expensive) hydronic heating system.

dymonite69 · Dec 28, 2008 10:23 am

Casa2

[So what I've done is captured the northern sun (using 6 solar panels ) and transferred this heat to the south via the hydronic system.

I see now.

Alternatives would be having a skillion roof system and high set clerestory windows to bring the sun into a the living areas. You would probably need to use double glazing and insulative window coverings to minimise heat loss during winter and at night.

Another consideration is using forced convection systems to transfer heated air from the south side to the north side e.g. heat transfer ducting kits.

Casa2 · Dec 28, 2008 10:45 am

dymonite69

Casa2

[So what I've done is captured the northern sun (using 6 solar panels ) and transferred this heat to the south via the hydronic system.

I see now.

Alternatives would be having a skillion roof system and high set clerestory windows to bring the sun into a the living areas. You would probably need to use double glazing and insulative window coverings to minimise heat loss during winter and at night.

Another consideration is using forced convection systems to transfer heated air from the south side to the north side e.g. heat transfer ducting kits.

An earlier design had a skillion roof. However, when I modeled it there was so little light coming in that I gave up on that. The good thing about the solar panels is that they can be mounted where there will be good sunlight hitting them throughout the day in winter.

An even earlier design had air movement, but I suspect that water can transfer more heat than air given a particular air/water pump power. The beauty of the water system is that it's a loop so the water pump only has to circulate water, not just push it if you know what I mean.

So in the ned 6 solar panels and hydronics it was. not the cheapest solution, but the one that I though would work the best (or could be made to).

Yak_Chat · Dec 28, 2008 1:01 pm

Quote:

It most certainly is, which is why we were thinking that tiles were our only sensible option (exposed slab having been excluded). No hydronic heating unfortunately as we couldn't make our budget stretch that far.

Good to hear.

Casa - sounds like your plans have changed lots since I last saw them and yes would like to review them again sometime.

I' mainly doing Perth trips each month at present so you might have to email them to me.
Steve

dymonite69 · Dec 28, 2008 5:36 pm

Casa2

The good thing about the solar panels is that they can be mounted where there will be good sunlight hitting them throughout the day in winter.

water can transfer more heat than air given a particular air/water pump power.

Definitely the most effective system if you can afford it. Every cubic metre of water holds 1500 times more heat energy than the equivalent volume of air.

taththi · Feb 24, 2009 3:40 pm

Not sure which hydronic thread to add this to but this one sounded good :p ...

Anyway - I'm in the process of deciding on a heating solution for our new place. We're in Tas, and the site gets all day sun (which can be until almost 9pm in winter!) We're on the top of a ridge, 4 acre block, with contours 30 degress West of North. We're planning to build with the main length of the house facing 25 degrees West of North.

The house is single-story but build on 2 levels, digging into the hill by way of cut-and-fill so the slab will be directly on the ground.

- I assume I only need to insulate the edges of the slab
- The front section (N facing) of the house we were going to use polished concrete and/or tiles to soak up the sun, with double glazed windows and a conservatory in the middle of the length (so it has internal glass walls as well making it a bit of a bubble)
- The back part of the house I hoped to have floating bamboo floors on the slab
- I wanted to hopefully combine our water heating with in floor heating and possibly other attachments (like the radiators) in a system like those shown here http://www.solarhydronics.com.au/hydronic_heating_systems.htm

Is that sounding like it'll be a good combo?

I originally wanted to build walls using strawbale for the R10 goodness but was put off by the extra cost and the fact that it still isn't listed as a building code standard (grr). Also because apparently the fire ratings tests done earlier need to be checked against new standards in Aus now, or something like that

I'd love to be convinced back to straw really as the alternatives that we're looking at like Heibel don't sound anywhere near as insulating.

dymonite69 · Feb 24, 2009 4:34 pm

taththi

We're in Tas

main length of the house facing 25 degrees West of North.

The house is single-story but build on 2 levels, digging into the hill by way of cut-and-fill so the slab will be directly on the ground.

- I assume I only need to insulate the edges of the slab

combine our water heating with in floor heating and possibly other attachments (like the radiators) in a system like those shown here http://www.solarhydronics.com.au/hydronic_heating_systems.htm

| I'd love to be convinced back to straw really as the alternatives that we're looking at like Heibel don't sound anywhere near as insulating.

You are at the limit of aspect before compromising your passive solar design (further west may result in overheating in summer).

Your issue will be the colder ambient temperatures leading to heat loss from your solar HWS.

You will definitely need an evacuated tube system. The problem is you will need a huge collector to heat both water and thermal mass floor. It will take an enormous amount of energy to bring your slab up to temperature. Do you just wish to heat the south side like Casa2. Slab edge insulation is adequate (see https://forum.homeone.com.au/viewtopic.php?t=14111) and definitely required for in-floor heating.

I am wondering though if this is going to be a cost effective heating solution for your capital investment?

Straw is a great insulator. Once rendered it is fireproof (a fire needs fuel AND oxygen). Aerated concrete (AAC, Hebel) is a reasonable insulator but not good enough on its own. Additional insulation is required.

Your floor mass (and earth berming) should be adequate for moderately sized windows but you can bump glazing and mass up by using reverse brick veneer.

Double glazing will make a big difference in efficiency for your climate (and I would budget this ahead of solar hydronic).

taththi · Feb 24, 2009 4:53 pm

dymonite69

You are at the limit of aspect before compromising your passive solar design (further west may result in overheating in summer).

Your issue will be the colder ambient temperatures leading to heat loss from your solar HWS.

You will definitely need an evacuated tube system. The problem is you will need a huge collector to heat both water and thermal mass floor. It will take an enormous amount of energy to bring your slab up to temperature. Do you just wish to heat the south side like Casa2. Slab edge insulation is adequate (see https://forum.homeone.com.au/viewtopic.php?t=14111) and definitely required for in-floor heating.

I am wondering though if this is going to be a cost effective heating solution for your capital investment?

Straw is a great insulator. Once rendered it is fireproof (a fire needs fuel AND oxygen). Aerated concrete (AAC, Hebel) is a reasonable insulator but not good enough on its own. Additional insulation is required.

Your floor mass (and earth berming) should be adequate for moderately sized windows but you can bump glazing and mass up by using reverse brick veneer.

Double glazing will make a big difference in efficiency for your climate (and I would budget this ahead of solar hydronic).

Thanks dymonite. I would have liked to have sat at true North however that would compromise our desire to hug the contours.

Yes we only envisioned heating the rear section of the house (3 bedrooms and the bathroom). The front part of the house (kitchen, living/dining, conservatory, study, master bedroom) sit along the north-facing front so I'm hoping they will receive enough heat during the day to release slowly for night time. The front section is by far the majority in terms of sq. m area.

I was also recommended to go evacuated tubes, why exactly is that the case? Are they not effected negatively by cold ambient temperature?

Regarding hydronic floor heating I was thinking that we could have a system like the linked one where the solar collection contributed heat to the tank however other sources such as solid fuel, electric or gas could add to the heating. Regarding that particular site it is unfortunately in Melb and not available for us, but hopefully there are others. Would you think it worthwhile if we were to use supplementary heating on top of the passive collection?

Yes I'd heard that rendered straw had a 4 hour fire rating in some US tests which I thought was excellent compared to other materials.

dymonite69 · Feb 24, 2009 6:40 pm

taththi

Yes we only envisioned heating the rear section of the house. The front section is by far the majority in terms of sq. m area.

I was also recommended to go evacuated tubes, why exactly is that the case? Are they not effected negatively by cold ambient temperature?

Regarding hydronic floor heating I was thinking that we could have a system like the linked one where the solar collection contributed heat to the tank\

Would you think it worthwhile if we were to use supplementary heating on top of the passive collection?

Where is your closest meteorological station based on this list:

http://www.bom.gov.au/climate/averages/ ... ames.shtml

This would give some idea about how your solar insolation and how much usable solar energy you have in winter.

Evacuated tubes are more efficient because the collector is effectively insulated by the vacuum around each heat collecting element. It is like a form of double glazing. BTW it has very little to do with the geometry of the tube allowing all angles of the sun to strike (although the retailers seem to believe this).

You can try to maximise the conversion of solar energy into heat with evacuated tubes but you are still dependent on adequate sunshine. Double the efficiency doesn't add to a lot more if you have precious little sun to start off with. I calculated that a 30 tube system could heat about 85L of hot water in the middle of an Adelaide winter (this is inadequate for household use let alone heat the slab to a decent temperature). You will still need quite a lot of boost energy.

I think a solar hydronic system adequately sized to perform in-floor heating in a Tasmanian winter will be an over-engineered and costly solution.

An Oregon government department agrees with this economic assessment as welll:

http://www.oregon.gov/ENERGY/CONS/RES/tax/Radiant.shtml

A ground-source heat pump would probably in the same ball park figure AND provide a cooling system.

Here is a CSIRO fire test on strawbale:

http://www.cmmt.csiro.au/research/paper ... ct.cfm/554

You can try emailing the engineering company to get a copy of the report for your council submission.

bdco@merlin. net.au

dymonite69 · Feb 24, 2009 7:20 pm

dymonite69

I think a solar hydronic system adequately sized to perform in-floor heating in a Tasmanian winter will be an over-engineered and costly solution.

An Oregon government department agrees with this economic assessment as welll:

http://www.oregon.gov/ENERGY/CONS/RES/tax/Radiant.shtml

To compare Heating Degree (Celcius) days

Portland, Oregon - = 2416
Hobart, Tasmania = 2095

Average solar insolation coldest 6 months

Portland = 1.8 MJ/day
Hobart = 2.1 MJ/day

Hobart is slightly warmer and has a bit more sunshine.

Source:

http://www.degreedays.net/#generate
http://www.gaisma.com/en/location/portland-oregon.html
http://www.gaisma.com/en/location/hobart.html

dymonite69 · Feb 24, 2009 8:43 pm

oops double post

gabrielpl · Sep 30, 2021 10:45 am

I was hoping to get some advice on this matter too. This post is a little older now but if anyone could give their suggestion on two possible solutions for us, that would be great.

We have an exposed concrete floor we'd like to add a covering as the workmanship of the burnished concrete was disastrous and we want to improve its appearance.

We're considering either an 3mm epoxy or 3mm micro concrete covering layer to improve the levelling of the floor and aesthetics. The epoxy layer seems easier more readily available and with experienced tradies in our area (Tasmania). The micro concrete can be a little more challenging to get, possible from OZ mainland, and we'd be risking with tradies with no experience applying it.

I am afraid a 3mm-thick epoxy layer might impact too much on the thermal absorption. I'd expect better absorption if using micro concrete instead.

Any ideas or suggestions on the matter? Thank very much!

alexp79 · Sep 30, 2021 11:46 am

Would it be easier and more pleasing to just go with tiles?

gabrielpl · Sep 30, 2021 11:54 am

Surely alexp79. Though I am dealing with the builder and trying to find a solution which might combine a more reasonable cost for them as well. Even though was their mistake it is hard to negotiate a covering which might be more expensive than they are willing to pay for.

I thought about micro-concrete (e.g. ecoflor . com . au) as it costs 40$/m2 and the finish looks good (on photos I admit). The 3mm epoxy was the builder suggestion but I am afraid about its isolating capacity.

Hope that clarifies.

Cheers

alexp79 · Sep 30, 2021 12:08 pm

Epoxy is insulating, however, the thickness is also very small, so total insulating R value will be quite low (less than 0.1 R, so barely noticeable).