I recall reading in this Group some years ago a proposal to cool a house by drawing in the cool air at floor level from the N side of the house and venting from the top level on the S side.
I've just bee poking around with the IR thermometer and from about 2' up the temperature is around 28C but the block paving at ground level is about 21C.
So there does seem to be scope for moving cooler air into the house.
The big question is how much air you can move. Passive with very large vent area, or smaller vent area with big extractor fan? Also, weatherproofing for the winter.
Has anyone done this, and if so what materials did you use?
Hmm... cat flap in front door would almost do it. Anywhere else would require serious brutalisation of the brick wall.
Are you shure you want to import , even the coolest air, from outside? I decided the recent "advice" about closing curtains daytime was nonsense. Have they learnt nothing about the greenhouse effect? You need any curtains to be on the outside of the glass. From Lidl/Aldi I bought some "privacy" screen 5m x1m of dark green material apparently stabilised against UV . Cut and joined so a 2.5x2m panel and 3 cup hooks into the flat canopy fascia over the main large window, so hanging loose about 6 inches from the glass of the large window . Today and yesterday max temp 26 deg C in the room, today max outside was
31C (professional Davis weather station down the road).
8 am overnight low of 24C , and no fan required today or yesterday. Previous heatwaves, don't know the temps, but even fans plral were not enough to be comfortable at times. For the other side of the house , tried a 2mx1m sheet of reflective mylar/ space-blanket, but rustles annoyingly so some more of that privacy sheet needs obtaining, otherwise worked equally well. I may even try 2 dinghy/yacht burgee pulleys, or such, fixed above the bedroom window to repeat the success of downstairs, hauling upwards a "sail" of thismaterial . Only used when present in the house, for duration of the sunshine , in case the wind gets up. Some years ago I made up a perforated metal sheet for replacing the wood loft access hatch during summers. But no purpose-made ventillation for the heat up out of the loft. I'm wondering if that is not such a good idea ,as if any air is drawn into the loft would be coming from ,at minimum today , 31 degC.
Not very sensible - I have just checked the temperatures at 16:10 - indoors is 27.2C, but outdoors it is 39C.
My too warm, but certainly cooler indoor temperature is a result of opening upstairs windows wide once the outside was cooler than the inside, to cool the house fabric down, then closing them tis morning along with blinds on the sun facing side of the house.
The ground surface in deep shade might be 21C but I expect the air immediately above it is a *lot* warmer than you think.
I have a thermometer at ground level on my N facing wall showing 35C at the moment (+4C on yesterday). That is measuring actual air temperature at about 3" off the ground.
If you have a cellar then you can pull fresh air in through there.
Closing the windows during daytime and opening as many as you can when the outdoor temperature falls below indoors is a decent strategy.
In rooms where you can't close the curtains then it might be advantageous to open any skylights to let the hottest air escape.
Otherwise it is better to move around the cooler air already in the house than introduce warm or even hot fresh air from outside.
There are some designs of cross flow heat exchangers that are intended to warm incoming cold air in winter but would probably work the other way around as well.
It's not recent and it's not nonsense and anyone could figure out for themselves that, given we don't have external shutters here (see other thread), the best you can do is close the curtains and windows when outside air is hotter than inside. Overnight you reverse that, as various bods are pointing out.
What you *ideally* need ain't necessarily what you can have. I'd love to have insulated, heat reflecting external shutters for this weather. But absent them, I close the curtains inside the house on the principle "don't let the best be the enemy of the good".
You need curtains to be on the outside of the glass, not the inside. Any old curtains or bed sheets or whatever , even just temporarily drawing-pinned to wood or carpet-taped to plastic window frames , but on the OUTSIDE of the glass.
Is that 21C the air a few cm above the paving or are you reading the temperature of the ground and you would need to take the cool air from a (very) long pipe buried in the ground to get 21C
You cannot measure air temperature with an IR thermometer. Note in the linked video you are not seeing the temperature of the hot air exiting the boiling kettle nor the hot air above the cup.
I've been working from homw with the cellar door open and the kitchen door adjar with tubs of water across the threashold. It does give me a "curtain" of cool air at the doorway, and within minutes of doing it the "office" area was noticable more comfortable, but the prevailing (very slight) breeze is coming in through the kitchen, I would need active air movement to suck the air from the cellar instead.
I do have an air blower, but it's a room heater.... :(
I picture getting some of that "elephant trunk" ducting stuff and Apollo-13'ing it to a small room fan.
Thats interesting, I've seen examples of them and thought it was just an architectural style fad, let alone their name and function. The ones I've seen would only apply with midday sunshine though
The hottest air cannot escape without letting outside air into the house to replace it, becoming part of the problem.
The primary concern is to , hoping you start with low overnight temperature, to then minimise internal solar gain to our insulated boxes of cavity walls and double glazing.
Although that is true if you don't do it then the upper storey of the house slowly fills up with the hottest possible air from the ceiling down. Typically the bedrooms where people will later try to sleep.
My own house has sufficient thermal inertia to withstand a few days of this and stay tolerable inside. Today was pushing it and the main living room got up to 25.4C which is something of a record. Nearby certified met office weather stations reported 39C (although I only saw 35C here).
My office (upstairs) became unusable just after lunchtime and remains so now. It is of modern construction and still above 31C.
We've just had the 2 minutes of light rain and now there is a nice breeze blowing through the house. In the past 30 minutes my upstairs has gone from 30C to 28C (outside still around 26/27C).
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