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.
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?
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
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.
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 :)
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
"That excessive bail ought not to be required, nor excessive fines imposed,
That is probably one of those semantic arguments that follows from there
not having been a legal maximum for exposure to radon set - hence there
is no level below which you can claim its "safe because the government
Yup. In fact many of the so called maximum exposure limits are if
anything too low anyway. If you remember the fuss about caesium release
during the Japanese earthquake - the levels set as "safe" are set on the
assumption that you will be exposed to those levels continuously.
Something that is actually hard to achieve with one off release of an
element with a half life of a few days.
There was a very good official publication around a few years ago
discussing the public perception of risk. One of their main
findings was that people have a very subjective assessment of
risk. If the consequence of something, such as an air crash, is
catastrophic, then the fact that the likelihood is remote does
not register, and the perceived risk is high.
The report also had some interesting comparison tables. One that
really surprised me was that deaths due to natural radon were
running at about half those due to road accidents
Chris J Dixon Nottingham UK
There is almost no radon in the air so its not going to be sucked into a
house with the air.
To maintain even a small pressure difference would require energy.
Most houses leak like sieves and it would take a lot of energy to maintain a
The reality is the radon gas seeps in from the ground with no pressure
difference needed between the house and the outside air. It accumulates
because of a lack of ventilation. Even a slight amount of ventilation would
get rid of the radon. Even the air bricks used in old houses would be
You don't get radon in new houses because a plastic membrane is enough to
stop it getting in and they use them to stop the damp.
We are not talking about a new house.
Radon is a heavy gas so it accumulates in basements that are open to
The OP is intending to suck the air from his basement and blow it into
his house. So he will be breathing radon. If I wanted to cool or heat
my house I would make a heat exchanger and I would bury pipes in the
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