Aerogel - Spaceloft Insulation for Fridge / Freezer

[magentawave]

I have questions about this Aerogel stuff please...

1) Is it true that 3/8" thick Aerogel is R-10?

2) How many 3/8" layers of Aerogel did you guys use to insulate your boxes?

3) What are the reasons to not use two layers of 2" thick Polyisocyanurate foam insulation from Home Depot (R-25.8) at only $2 per square foot verses the $5 per square foot Aerogel?

Thanks!

[Mischief2]

Hi Magentawave,

Firstly, let me say that I'm not an expert in Cryogel Z so the only information I can give you is the experiences that I've had with the Cryogel Z. In answer to your questions:

1) I can't confirm the exact R rating however to give you two examples of the results we have had:

(a) When the cold plates were first installed in both the fridge and freezer compartments, prior to the countertop or lids being fitted, the compressors were run for approximately 90 minutes to check the system was working correctly. In that time, both the fridge and freezer plates began to freeze and the temperatures in the base of the cabinets were approx. -10 to - 12 celsius. The next morning (13 hours later) both plates still had heavy frost over them and both cabinets were still around -8 celsius. Given they had no countertop or lids we thought this was a pretty good example of just how little cold could leach through the base of the cabinets. This was in late Oct so late Spring here in Sydney.
(b) The second demonstation of just how well the Cryogel Z works for us was after a 12 day holiday on the boat we emptied and cleaned the fridge & freezer comparments then left the lids open to prevent mould/smells etc. When we returned to the boat the following weekend (6 days later) the freezer plate still had heavy condensation on the lower half of the plate and the bottom of the cabinet was about 6 degrees (celsius) colder than the ambient temperature. This was in mid summer.

2) We, knowingly, used much more Cryogel Z than we perhaps needed to. We used 10 layers on the base of both cabinets, 6 layers around the fridge walls, 8 layers around the freezer walls, 6 layers dividing the two cabinets and 4 layers in the countertop and lids. We used large amounts of it because we're moving aboard our boat this year as our retirement and plan to cruise the tropics for the foreseeable future. Given a rebuild of our old fridge/freezer system was unavoidable, we decided to do the best insulating job we could. As it stands at the moment, once we've brought the temperatures down to 4 degrees celsius (normal fridge temp) our fridge compressor doesn't come on for days (6 is the record). In the beginning I would turn temp knob to make the compressor come on as I thought it wasn't working properly. Our freezer gives us deep freeze temps (-15 to -18 celsius) with no effort (we have no problem keeping ice cream) and no condensation on the countertop. Both systems together use about 30 amps per day and we have left the system running for several days, while our boat's on it's mooring, with just the solar panels for charging and still have full batteries when we get on board.

3) In answer to your question 3, half the thickeness of Cryogel Z would provide substantially better insulation leaving you with a larger cabinet volume. The Cryogel Z is hydrophobic so condensation doesn't affect it's performance at all and finally, it loses about 2% of it's thermal properties in over 40 years! Most other insulating materials lose about 15% in 5-7 years and continue to lose their thermal properties as time goes on and lastly, any moisture affects their performance substantially.
I'll further add that here in Australia the Cryogel Z is substantially more expensive than in the US. About AUD$100 per square metre and even given this price, we have no regrets about using it. Our fridge/freezer system will no doubt out live us (providing we don't sink the boat that is ).

Sorry that's so long winded, hopefully it's of some help.

Kind regards

[magentawave]

Mischief2 - That sure sounds like amazing stuff and thanks for taking the time to comment! Now I just need to price out the cost of that stuff verses the Home Depot stuff verses the space I'd gain in the box.

[robert sailor]

I used Aerogel in our fridge as well with excellent results. Our box size is 5.8 cu feet. I used 6 layers all around except the bottom and it got 7 layers. I bought it off a fellow that had ordered too much for his job so it was discounted but it still cost me about $700 just for the insulation. Home depot insulation is going to be dirt cheap compared to Aerogel. Our fridge uses a keel cooler type and we use around 25+ amp hours per day in the Med summer.

[senormechanico]

The R value of Aerogel/Cryogel/Pyrogel is "per inch".

When comparing materials for a boat box, it's important to avoid moisture ingress.

Polyisocyanurate is hygroscopic (will absorb water) whereas Aerogel product is hydrophobic (repels water).

[robert sailor]

We used foil for heat reflection as well as a good vapor barrier, it wasn't a small project.

[magentawave]

I just spoke to a rep for R-Max polyiso foam insulation, the stuff at Home Depot, and she said it doesn't absorb moisture because both sides are foil wrapped. She also said it doesn't wick into the cells of exposed edges but to keep it totally waterproof that I should wrap the cut edges with foil tape. So polyiso isn't hydrophobic, but based on what she told me, why would that matter...and especially if I put a hard waterproof layer of something between the polyiso and the inside of the fridge?

I need to weigh the cost of 3 layers of Aerogel (R-30) at $15 per square foot verses two of 2" polyiso (R-25.9) at $2 per square foot and see if it makes sense because I know I'll end up with a ton more space in the fridge if I use Aerogel.

Originally Posted by senormechanico

The R value of Aerogel/Cryogel/Pyrogel is "per inch".

When comparing materials for a boat box, it's important to avoid moisture ingress.

Polyisocyanurate is hygroscopic (will absorb water) whereas Aerogel product is hydrophobic (repels water).

[magentawave]

I assume the heat foil should be pointed towards the outside of the box?

Originally Posted by robert sailor

We used foil for heat reflection as well as a good vapor barrier, it wasn't a small project.

[Cotemar]

The Spaceloft has an R-Value of R10.3 per inch. So, to attain an R-Value of R30, you must have at least 3 inches of product thickness. Because the thickness of a single sheet is 0.4" (10mm), you would have to have eight layers which would net almost an R-Value of R33. Three inches of Spaceloft would be equal to 7.5 layers. That's why you need 8 full layers. By this calculation one layer of Spaceloft would be equal to an R-Value of 4.12 per 0.4" thickness.

Aerogel .4 thick X 8 layers = R33 at 3.2 inches thick


Hydrophobic Silica aerogels are specially formulated to repel water and to not absorb moisture from the air. Where Classic Silica tends to shrink and cloud in humid environments, Hydrophobic Silica retains its transparency and integrity. Floats on water without damage! Excellent for applications involving absorption of hydrophobic substances such as oil.

[magentawave]

Thanks for clarifying because I totally misread the R Value for that stuff before. I thought one 3/8" thick layer was R-10 but now I know I'd need 3 layers to get a little over R-10. I'm still going to price this out and compare it with polyiso so don't know yet if it will be worth the extra cost to get another inch per wall of space for close to the same R Value. We shall see...

[socaldmax]

Originally Posted by Cotemar

The Spaceloft has an R-Value of R10.3 per inch. So, to attain an R-Value of R30, you must have at least 3 inches of product thickness. Because the thickness of a single sheet is 0.4" (10mm), you would have to have eight layers which would net almost an R-Value of R33. Three inches of Spaceloft would be equal to 7.5 layers. That's why you need 8 full layers. By this calculation one layer of Spaceloft would be equal to an R-Value of 4.12 per 0.4" thickness.

Aerogel .4 thick X 8 layers = R33 at 3.2 inches thick


Hydrophobic Silica aerogels are specially formulated to repel water and to not absorb moisture from the air. Where Classic Silica tends to shrink and cloud in humid environments, Hydrophobic Silica retains its transparency and integrity. Floats on water without damage! Excellent for applications involving absorption of hydrophobic substances such as oil.

Wait a minute...

If Spaceloft is R10.3 per inch, and the Polyiso is R25.8 per 2 inch slab...

It would seem to me that the Polyiso is a better insulator at R12.4 vs R10.3 for Spaceloft. I must be doing the math wrong, or misunderstanding something.

[Celestialsailor]

Originally Posted by magentawave

Thanks for clarifying because I totally misread the R Value for that stuff before. I thought one 3/8" thick layer was R-10 but now I know I'd need 3 layers to get a little over R-10. I'm still going to price this out and compare it with polyiso so don't know yet if it will be worth the extra cost to get another inch per wall of space for close to the same R Value. We shall see...

Yup...I made the same error but I can report that the efficiency here where it has been plenty warm at times is almost the same as it were in northern latitudes. I was told to expect up to 50% reduction in efficiency but I'm seeing more like a 5-10% reduction. I'm using 3 layers of 10mm. Aerogel, a vapor barrier, 2" of blue foam around that, then back filled with pour foam. I believe the thinnest area is 3" and only at a corner and 4"s+ everywhere else. Please wear protective gear while using this stuff. It's nasty and gets everywhere. It's best done outdoors.

[Matt Johnson]

Originally Posted by socaldmax

Wait a minute...

If Spaceloft is R10.3 per inch, and the Polyiso is R25.8 per 2 inch slab...

It would seem to me that the Polyiso is a better insulator at R12.4 vs R10.3 for Spaceloft. I must be doing the math wrong, or misunderstanding something.

This is R 12.9 at 2" thick. You would need 4 inches for 25.8.

[socaldmax]

Originally Posted by funjohnson

This is R 12.9 at 2" thick. You would need 4 inches for 25.8.

Oh, OK.

So 3 inches of Aerogel is R31, and 4 inches of polyiso is R25.8. Got it. So if one had 4" of space, the aerogel would give R41.2 vs R25.8 for polyiso. That's a pretty good increase.

[Mischief2]

Hi everyone

Just a reminder while everyone's doing their calculations - Aerogel Spaceloft and Aerogel Cryogel Z are different products. Cryogel Z has a much higher R rating than Spaceloft, with a price tag to match. Just want to be sure everyone's comparing apples with apples.

Kind regards