The No heat basement experiment

[Seasoned Oak]

Im trying to insulate a mostly underground basement so it remains above freezing no matter what the outside temps are with no additional heat.
Im rehabbing the home and it goes with out heat for days at a time and i have water in the basement. While im working i have wood heat.
Being the average underground temp around here should be about 50 degrees it is possible.
I do know of other 1 story homes with undeground basements that never go below freezing with no additional heat even on the 1st floor due to the warmth coming from below.
This can be very usefull information for part year residences,cabins ,vacation homes ect.

 

[newburner]

Our basement is unheated and uninsulated as well. It always stays between 50-55° year round due to geothermal heating.

 

[Seasoned Oak]

Our basement is unheated and uninsulated as well. It always stays between 50-55° year round due to geothermal heating.

Well you do have some heat coming off the GEO equipment and water heaters and some from above. My uninsulated basement where i live stays above 70 with no heating units just from the heat coming off my solid fuel boiler and stoveipe in the back room and total basement is 1000 SF.
The one in experimenting with will have zero heat input on weekends when im not there to operate the woodstove.

 

[newburner]

Well you do have some heat coming off the GEO equipment and water heaters

By "geothermal heating" I mean the natural heat from the earth.

There is nothing in my basement that creates any heat.

 

[Circus]

The No heat basement experiment Im trying to insulate a mostly underground basement so it remains above freezing no matter what the outside temps are with no additional heat.
quote].

That's not really an experiment. It's common knowledge and practice

 

[woodgeek]

I get the concept, but in a region where average January temps are close to freezing (like SE PA), it doesn't take a lot of BTUs to keep things above freezing.

Even so, I suspect that passive solar gain add a few degrees on average too.

 

[Where2]

I have one of these "experiments" also. I would like to log the temperatures during the entire winter, without being at the site or having any PC there. Has anyone found any temperature data loggers with downloadable memory for a reasonable cost? I need to be able to set them up and ship them for deployment.

Having a humidity reading wouldn't hurt either, if the additional expense doesn't break the bank.

 

[Seasoned Oak]

That's not really an experiment. It's common knowledge and practice

Large number of variables. How many walls are underground and how deep. Walls part underground and part above. Windows and doors. Air sealing. thickness and composition of walls.

 

[Seasoned Oak]

I get the concept, but in a region where average January temps are close to freezing (like SE PA), it doesn't take a lot of BTUs to keep things above freezing.

Even so, I suspect that passive solar gain add a few degrees on average too.

No solar gain in a basement
Last year the water and well pump froze solid in this basement. I figure i can probably get close to no freeze situation with air sealing alone. I also plan to add sheet foam to exposed outside walls to try to keep it above 40.

 

[Seasoned Oak]

By "geothermal heating" I mean the natural heat from the earth.
There is nothing in my basement that creates any heat.

OK i follow. I suspect you get a small amount from above

 

[woodgeek]

I was thinking solar gain on the upper story....if the upper is above freezing, it helps the basement.

I think a big issue is basement airsealing. Lots of folks freeze pipes when the basement is at 40°F or warmer because there is a cold 'jet' of infiltrating air from a exterior penetration or under a gap n the sill.

 

[jebatty]

Has anyone found any temperature data loggers with downloadable memory for a reasonable cost?

Google "temperature logger" and you can find lots of them.

 

[Circus]

airsealing. Lots of folks freeze pipes when the basement is at 40°F or warmer because there is a cold 'jet' of infiltrating air from a exterior penetration or under a gap n the sill.

Mouse holes plague me. I've found entire interior hollow spaces like floors or walls ice cold from them. Those illegitimate offspring!

 

[Seasoned Oak]

I was thinking solar gain on the upper story....if the upper is above freezing, it helps the basement.
I think a big issue is basement airsealing. Lots of folks freeze pipes when the basement is at 40°F or warmer because there is a cold 'jet' of infiltrating air from a exterior penetration or under a gap n the sill.

No windows in the upper story yet. Upper story is actually colder than the daytime highs due to overnight temps. Lots of air infiltration though. iv sealed the worst ones. ONce it really gets cold out it will help me find the others. Then on to foam sheathing on walls.

 

[STIHLY DAN]

How are you going to make the foam look half decent?

 

[Seasoned Oak]

How are you going to make the foam look half decent?

Thinking of covering it with something also to prevent damage

 

[STIHLY DAN]

Interested in what you cover it with.

 

[Seasoned Oak]

I have a lot of the DRI-VIT plaster cement that goes over foam. You see it everywhere on chain restaurants like mcdonalds.
First a fiberglass mesh for strength then a scratch coat and a surface trowel coat for looks.

 

[WiscWoody]

My basement never freezes even with one wall being a framed walk out wall. Even last winter with our near 8000 heating degree days. I figure the upstairs must radiate some of its heat downwards.

 

[Seasoned Oak]

My basement never freezes even with one wall being a framed walk out wall. Even last winter with our near 8000 heating degree days. I figure the upstairs must radiate some of its heat downwards.

It does , plus the ground radiates heat upward. If the space is tight and mostly underground it should not freeze. My project has no heat anywhere when im not there. So its fighting cold from above as well as exposed walls. A present it stays 10 degrees above outside temps which is not that good. hope to get it between 20 and 30.

 

[jebatty]

Basements .... when our walkout basement gets down to about 50F I start adding some electric heat to maintain a 50-55F temperature. The basement is about 1500 sq ft, one large unfinished area and two smaller finished areas. The unfinished area is partially insulated with foam on one exterior wall and interior fiberglass on another exterior wall. The finished rooms are fully insulated. All can be separately heated. Usually the basement drops to 50F in early December, this year it already is at the 50F level. I keep thinking about excavating around the foundation to add 2-4" foam board. That thinking has diminished with our PV system that now provides sufficient net metering credits to cover the cost of the electric heat.

 

[DickRussell]

Interested in what you cover it with.

Some of the ways this can be done are described here: http://www.greenbuildingadvisor.com...ght/how-finish-exterior-foundation-insulation

I used the technique of modified surface bonding cement troweled over self-stick mesh, to around 1/8" thickness. It's been three years now, and I haven't seen any cracking or chipping. The surface is tough, although I'm sure that if I hit with a hammer I'd do some damage. Even up close, it looks like gray concrete. I applied the coating to perhaps 6" below grade. It took time applying it, and I had to work with small batches, no more than I could trowel on and smooth out in ten minutes, or it would stiffen and be difficult to work. If I look closely, I still can spot the places where one batch ended and the next began.

If I had to do it all over, I suspect I'd use EPS rather than XPS (cheaper), and apply it all on the inside of the walls, with studs on the flat for creating wiring cavities and for screwing on sheetrock (necessary for thermal/ignition protection inside). Certainly this makes more sense than excavating a foundation that already has been backfilled.

For sure, insulating the walls keeps the basement much warmer, although in my case there is R-20 foam under the slab as well. But in the unheated attached garage, the framed walls and ceiling are insulated, as is the door, the frost walls are insulated on the inside down to footings, but the slab itself is not insulated. At the coldest part of last winter, with multiple days in the single numbers and below zero, the coldest it got out there was 37 F. Yes, deep ground heat can keep the space above it from freezing, as long as you keep that low level heat from escaping to frozen ground and cold air with insulation.

 

[Seasoned Oak]

First really cold night with no heat and a surprising 40 Degrees at floor level. Outside temp around 20. On air sealing alone. Still a lot of air sealing to do ,can see small amounts of daylight in too many places. Right now with the wood stove going its around 60.

 

[begreen]

Keep sealing those leaks. A 1/8" by 72" crack is equal to having 3" x 3" hole in the wall.

 

[Seasoned Oak]

Since i sealed it up it hasnt gone below 38 Deg. Ill check it again today after 2 full days with no added heat and below freezing outside temps 24/7 . Edit: Still 38 . Colder outside, but temps do not seem to go lower than 38 so far, with no heat at all added.