# Using basement to cool house



## ms_metis

We live in a 2 story house with a basement. The basement has 10 foot walls. Of that, only about 2 feet is not under ground. The temp in the basement is about 60. It is unfinished and concrete (not the blocks). We live just outside Philadelphia.

I'm wondering if we can use the basement air to cool the one or two living floors. 

We have a wooded lot. The garage faces south. 

Also wondering if we can reverse the process in the winter and use the basement to "pre-warm" air for heating.

Advice...Suggestions?
BC


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## Harry Chickpea

There are a couple of problems with the idea. Warm air holds more moisture. As the air is cooled in the basement, a lot of the cooling energy goes to condensing out the water (look up "heat of vaporization"). That makes your basement damp and moldy, and the air coming out of it feeling damp and uncomfortable.


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## ms_metis

Currently the basement air isn't damp or moldy. It's actually very dry. But if I understand you correctly, you are saying that as the air circulates, it will become damp/moldy due to the hot/humid air upstairs?

(I'm googling heat of vaporization now)...


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## WisJim

Over the long term, the basement will warm up and get damper. I remember a good book on superinsulated houses from years ago, and the author had a scheme using his window sized air conditioner to cool the basement at night, when it was already cooler outside, and then use this cool basement to cool his house as you are suggesting. The big advantage was that the A/C dehumidified and cooled, and using it at night saved energy running the A/C. Using the basement as originally suggested would work until the basement mass warmed up and got damper.


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## ms_metis

Thanks for the book suggestion.

So, one could buy a smaller AC for the basement to cool and take out the moisture. How do I get the air upstairs? Currently we have central air. The house is 4 years old. On a hot day, the top floor is uncomfortable by 1pm (maybe 2pm).

What about running pipes of air along the walls to help cool off the air?


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## nancy237

Does the basement have steps that enter the house ??
What about a fan between the basement and upstairs that sucks 
air from the basement and blows into the upstairs.

Would a dehumidifier work if the air is damp??
We keep one in the garage in the summer and it 
sucks out a gallon of water a day from the garage air.

seems it would use less energy than an AC.


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## Mid Tn Mama

We find that by opening the basement door and running overhead fans it cools the house quite well. Even better if you put a fan in the upstairs window to pull up the basement air.


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## SolarGary

Hi,
Here is a good story from Fran on how he used a combination of basement air and stack effect to avoid using his AC at all.

http://www.builditsolar.com/Projects/Cooling/BasementFan/BasementAirCooling.htm

The system works very well for him. I suppose it is climate dependent, but the system is so simple, it seems to me its worth a try. 

You might think the basement would heat up over the season as you transfer "coolth" from the earth, but Fran reports no such problems, and there is a whole lot of cool dirt behind those walls.

I think that his idea of using the thermal stack effect from basement to attic is also a good one, and worth a try.

Many more simple cooling ideas here:
http://www.builditsolar.com/Projects/Cooling/passive_cooling.htm


Gary


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## wendle

How many south facing windows and/or doors do you have? Watch them during the warm hours of the day, are they collecting heat? I put outside reflective shades over my bay window(big heat collector in summer) and the greenhouse area outside my back door. I couldn't believe the temperature difference. Refrigerator and freezer can create some heat in the house too. I used to have both in my kitchen , huge old things. When I switched to a smaller apartment size fridge and a chest freezer(in the basement) the temps dropped. I run a fan from the East(where my shade trees are) and exhaust to the west. Just a few things that might help keep things cooler.


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## bookfarmer

For several years we lived in a Pennsylvania farmhouse built in the 1890s. For a long time I couldn't figure out the odd rectangular pieces of wood in the floors. Then it finally dawned on me. Someone had taken out or floored over the passive vents that opened from basement to first floor and first floor to second. With no air conditioning in the 19th century, folks had figured out how to move the cool basement air up through the house. If we had continued to live there, I had intended to open these vents again to take advantage of the chimney effect that Fran describes in his article.


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## ms_metis

Thanks all...

We do not have any south facing doors or windows besides the garage. And the basement is very dry. My husband and I did read Fran's story on BuilditSolar already and thought it might work, but we were wondering if there were any other options.

Specifically, why can't you run pipes full of air or liquid (as they do outside in the ground) along the walls of the basement. Then pipe cooler air to the furnance and turn the house fan on? Like indoor geothermal?


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## WisJim

I find that in our climate, in western Wisconsin, our basement walls start to show condensation from humid summer air if we circulate outside air into the basement. It takes awhile, but it gets damper. The problem with a dehumidifier instead of an A/C unit is that the dehumidifier also heats as it gets moisture out of the air, and the A/C cools and dehumidifies at the same time.


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## mnn2501

My parents used to turn the furnace fan (fan only) on after covering the cold air return vents in the upstairs - so it was only drawing from the basement cold air returns. It helped on really hot days-- of course I grew up in MN so there really were not that many really hot days.


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## genebo

For a small decrease in A/C bills and a boost in A/C performance, put a return line to the A/C from the basement.

Also consider putting a larger return or an additional return in the top floor. That will pull the hot air out of the top floor.

Large variations in temperature, such as the overly warm upstairs, can be due to stagnant air.

Genebo


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## Wisconsin Ann

I'm late to the discussion, but want to relate a couple of things done in houses I've lived in that work quite well.

In our current house...large Victorian house with a lovely cool stone basement...we can open the door to the basement, turn on a fan in a 2nd story window to exhaust air, and have a nice circulation of cooler air. It doesn't act as WELL as a whole house airconditioner, but it does keep the air moving, and pulling cool air from the basement. works well enough except on the hot muggy days.

I used to live with a couple who had a square house, 2 stories, with attic and basement. (the style has a name and for the life of me I cant' remember it just now). The husband is a MAJOR pain in the patoot about saving money. He researched and tested and discovered his best bet for cooling was to put a box fan in the attic (he mounted it in the hole that the ladder usually goes up into) to pull air up from the rest of the house and exhaust it up into the attic...where he had put a couple of vents with small solar fans to vent hot air out into the atmosphere. He'd open the door to the basement, flip a switch and you'd feel this cool breeze EVERYWHERE in the house. It was amazing. 

What you could do, with the fan on the furnace....shut ALL the air intakevents upstairs, and open a vent for the furnace to suck in air from the basement. That may be enough cooling for most months. Kind of depends on where you're located. Around here, I'd run a dehumidifier in the basement to keep down the humidity. Keeps the air nice and dry/cooler feeling.


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## WisJim

Wisconsin Ann said:


> Around here, I'd run a dehumidifier in the basement to keep down the humidity. Keeps the air nice and dry/cooler feeling.


As I mentioned above, it would be better to use a small A/C unit to cool and dry the basement, as a dehumidifier will add heat to the area as it removes moisture.


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## Farhan

usually Air are two typres the warm and the cold one, cold is normally move to below and hot is opposite in direction mean Upward. so that you should use a fan for ventilation of the basement cool plus you should covered your walls or roof from sun heat, using heat reflective paints or chemical, check https://www.heatproofing.pk/heat-proofing-services/


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## mnn2501

FYI, this is a 9 year old thread.


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## Farhan

mnn2501 said:


> FYI, this is a 9 year old thread.


FYI, i just want to put my first comment on thread, hopefully its an answer of thread


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## Gary in ohio

ms_metis said:


> We live in a 2 story house with a basement. The basement has 10 foot walls. Of that, only about 2 feet is not under ground. The temp in the basement is about 60. It is unfinished and concrete (not the blocks). We live just outside Philadelphia.
> 
> BC


I early spring when its just starting to get HOT I use the "FAN" and run it to take the cool out of the basement. Its pretty good until the humidity starts to climb.


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## R-Farm

I live in a straw bale home in GA that has a "storm shelter" aka basement with no doors or windows, access is only from inside the home. It is cooler down there, usually 62F in the winter and 72F in the heat of summer, but it is also musty in the summer. Instead of routing this musty air into the living space, I have chose to vent it out of the home using a radon fan. The fan attaches to a pvc pipe that pulls air up from the basement through a first level wall and outside. I have the fan on a timer and only run it from 9pm to 9am, the coolest hours of the day usually. This creates a downdraft in the evening that provides 2 benefits, it evacuates the basement of musty air and it pulls the warmer interior air out of the home allowing it to more rapidly replace with cooler mid 60F night air. I failed to mention I do open the windows in the evening as well as 4 Velux skylights that vent the warmer air on the second level directly out of the home. This helps tremendously and on most days my 9,000 BTU mini split a/c unit does not run for more than 1-2 hours maintaining a cool 72F on the lower level of the home. We do not use the upper level much and it does heat up to mid 70's during the day, but drops into the 60's at night. I am also off the grid solar and am very wary of every amp I use.


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