Cool air drawn in from N side of the house?

[Andy Burns]

That's the general idea with the fixed ones, let in the nice shallow early/late light, but keep out the bearing-down heat, some can be angled

[N_Cook]

Presumably from "greenhouse effect" solar gain thru the window/s. Whether the sunlight is striking carpets,furniture, curtains or internal blinds, that heat is being absorbed and retained on the inside of the glass. Try hinged external shutters and long-pole or my non-patented flying sail sun shade for upstairs levels.

I did not see her name or institution but an academic expert in buildings in a climate changing world, sensible statements. She advocated the retro-fitting of EXTERNAL shutters and slagged-off the concept of air conditioning. Her points were

1/ only for those that could afford it 2/overstressing the electricity supply 3/ (I'd not realised before) all that AC waste heat is dumped into the outside air to add to the overall urban heat island effect

[Andrew]

I have a survival 'blanket' which is some sort of tough metallised plastic, silver on one side and gold on the other.

On Monday I taped this to the outside of my south-facing aluminium patio doors (nasty un-thermally-broken type) with some of that blue masking tape. Brilliant result.

It didn't reach down to the bottom 18 inches and the inside of the frame and glass at this section was 47C according to my laser thermometer. Above the line where the outside reflective film started the glass and frame was just slightly warm.

I'm going to get one of those 'sails' that almost every home in Oz seems to possess and string between trees or connected to the side of the house.

[N_Cook]

My odd sheet I had hanging around from winter walks was also the silver and gold ones,very effective as a tryour, probably too thin to be reliable left in sunshine for days on end. Locallywe hadsome strong convestion powered wind rustling that sheet , too much to use regularly

I'll get some more strong "privacy screen" and a pair of pulleys for suspending outside an upper floor window, and some small panels left over to hang over some smaller windows. Yesterday evening I accidently continued my insolation versus insulation experiment. 26 deg C was the maximum room temp thru the height of sunshine yesterday , outside air temp 31deg C. Late afternoon clouded over and some thunder so I unclipped the screen . But early low angle sun returned for about half an hour , partly obscured by trees and houses so low level weaker sun on about half the main window for half an hour but the room temp went up to 27 deg C (thermometer positioned 2m from the window and never indirect sunlight, despite closing the internal curtains.

[Martin Brown]

The simplest quick fix using easily available materials is to hang holographic metallised film from the tops of the windows to reflect most of the light and heat away (whilst still letting enough in to see by).

The other one is the polystyrene backed foil sold for putting behind radiators. Lightweight and easy to handle it can slow down heat ingress through a sun facing window considerably (but blocks all light).

I haven't done the experiment to see which way around is optimum but I would expect it to be mirror side facing inwards. Allowing the well insulated side to get hot and radiate efficiently in the thermal band. (mirrors make very poor radiators)

My office at university had external roller blinds to shade it from the sun much like shops used to (and some still do).

Air conditioning has its place but it is overkill in the UK when we only have a few days a year when it will be really needed. My house can be maintained cool by careful management of passive ventilation overnight.

That is always a problem.

That is due to lack of investment and infrastructure planning. It isn't like scientists and engineers haven't been warning the government for decades that there was a serious problem. Dash for gas may cost us dear this winter since total UK gas storage capacity is a paltry 7 days.

This is from 20 years ago - he has made the same points ever since.

It has to go somewhere and in cities it makes air considerably hotter.

[David]

Thinking of drawing the air in close contact with the ground to use the ground as a coolant.

Next step would be to bury an air duct in the ground so it is at ground temperature and pass the air through that.

Not that I'm planning on digging up my drive this week!

Cheers

Dave R

[David]

Hmmm....we do have a suspended floor over most of the house, with air bricks around the walls below the DPC.

The floor is insulated to prevent the rooms from getting too cold!

We like the solar gain from the South facing rear of the house for nearly all the year as it cuts down on the heating.

Just not that much solar gain when it is very hot.

We also have a large veranda area with a clear(ish) plastic roof which makes the outside much more liveable in spring and autumn but is acting like a green house at the moment.

The Lord giveth etc.

I wonder how much air/how big a fan would be required to draw all that cool air up into a downstairs room? This assumes ventilation at the top of the house to take away all the hot air.

Another Round Tuit project.

Cheers

Dave R

[alan_m]

After a short while wouldn't all the cool air under the floor be sucked up to be replaced by high temperature outside air input via the air bricks? This hot air would then have to sit under the floor for some considerable time before it could be used to cool a room.

It may be cooler under your suspended floor but to use it for continuos cooling the replacement air also needs to be cooled - perhaps in a buried 200m pipe as used for ground sourced heat pumps.