Internal house air cooling

[jgharston]

The weather having got better after being knocked out by the heat last week, I've decided to resurrect an old plan to install some sort of active ventilation in my house. My cellar is a huge cold source, but I prefer to occupy the living room and dining room. My plan is to draw the cold air out of the cellar and circulate it into the living areas of the house.

Some questions: What would be better, actively draw the warm air out of the house and have the negative pressure draw replacement cold air from the cellar, or actively draw cold air from the cellar and have the positive pressure passively draw the warm air out of the house?

While the cellar is what I call "bone dry", as with any underground stone-built structure there is imperceptable damp, noticable if things like paper products or sacks of cement are left for extended periods of time. Will drawing this slightly moist cold air into the warmer areas of the house cause any condensation or other issues?

Ta.

JGH

[NT]

Any plan that includes drawing air out of the house will necessarily include air entering, which is not what you want on a hot day. Just circulate air between cellar and ground floor and you'll get more coolth.

Another effective way to get cooling at trivial cost is to run extractor fan(s) overnight. Given enough air moevment, this slowly cools down the masonry, reducing peak indoor temp the following day. The amount of air moevment needed is much bigger than people imagine, running the 4" loo fan at night isnt going to do much.

NT

[jgharston]

Ah, that's a good idea. When it gets swealthering hot I have an urge to lock the weather out, circulating the air within the house between the cellar and the living quarters would make that feasible (along with a bit of leakage to allow oxygene in :)

JGH

[Matty F]

I wouldn't do that. Radon gas accumulates in cellars.

the UK, radon makes up about 48% of the radiation dose a person receives.

[John Rumm]

Depends where in the country you are... in the south west perhaps.

[S Viemeister]

Aberdeen has a lot of radon.

[harryagain]

If warm air from the house gets into the cellar you will have a condensation problem in the cellar. Also, you may get mould spores from the cellar in your house, some are harmfull if inhaled, others may sart a rot problem.. Your cellar will soon warm up in any event.

Go out and buy yourself a proper aircon unit. Get a reversible one (that pumps heat into the house as well as out) and save on your fuel bills in cold weather too. There are ones out there you can install yourself too.

[Matty F]

Pretty much everywhere in the world has radon coming out of the ground. In my country we tend to not have cellars. My house is supported by piles a metre off the ground. So no radon in the house.

[Hugh - Was Invisible]

Need to watch out for condensation in the cellar if warm damp air is being moved down there.

[jgharston]

I've already got a source of free cold, why should I pay to generate what I already have ample supplies of.

JGH

[John Rumm]

well it has lots of granite as well - and the two often come as a package...

[John Rumm]

One might argue because the proper aircon will deal with the moisture problem into the process. However you may get away with a dehumidifier instead in this instance.

[harryagain]

You only think you have. It is a very limited source of "freecold". All this has been thought of before (and discounted for the reasons I gave.)

[S Viemeister]

Indeed.

[NT]

These sort of semi-passive cooling approaches dont give as much cooling as ac, but its enough to make a big comfort difference.

NT

[Newshound]

This line in that link is all I need to know to form a judgement:

"Usually a home has a slightly lower air pressure than the external air, thus drawing in air, including radon."

[Bob Eager]

Aha! Windmills in the windows => free power!

[Onetap]

Second that. The cellar is cool because the air is stagnant, it has been cooled by the ground absorbing heat from the walls over a long time and it is cooled by evaporating moisture from the cellar walls. Start air moving through there and the reduction in the air temperature is determined by the rate of heat transfer from the air to the walls (approximately bugger all), the walls to the ground (less than b.a.) and the moisture pick up (also bugger all).

There are some buried heat pipe type devices that cool the air intake to commercial ventilation plant, I forget the name. The dT was only 2 or 3 degC and it was a lot of buried pipes. It could only make a return for large AC plant.

[Matty F]

So what is your judgement then?

[Tim Streater]

Radon is likely to be a problem only in certain areas, like Cornwall, where there's lots of granite (which contains radium or uranium IIRC). The link above says "There is no safe level of radon". In fact we don't know this to be true. Radiation damage has been measured only for higher levels of exposure. There is an *assumption* that this may be linearly extrapolated down to low levels, but there's no evidence that this assumption is true.

Life has been living with background radiation ever since it came into being on Earth some considerable time ago. It damages cell DNA, as do free radicals, produced as part of normal cell chemistry. There are repair mechanisms for this, which wear out as we get older. There is in any case nowhere in the universe where you can be free of ionising radiation.