Hot steamy nights

[JohnD]

For some reason I'm bothered by it a lot more at night.

 

[JonathanM]

Air con feels like a last resort.

I already have a few different fans.

What I am trying to discuss are solutions which actually reduce the temperature, rather than just blow hot air.

 

[Odds]

What you need is a Barajeel - a wind tower. Convert your chimney stack and tell us all about it in 'My Projects'.

 

[JonathanM]

What you need is a Barajeel - a wind tower. Convert your chimney stack and tell us all about it in 'My Projects'.

That sounds like the thing I read about a few years ago.

I once read about a way of designing houses to keep them naturally cool, so that air is drawn in from downstairs and then it vents the hot air somehow out of the top. But I can't remember what it's called.

It doesn't look like a retrofit!

Window film sounds like the best option so far. Although curtains help quite a bit, they don't actually stop most of the heat coming in through the glass. I have thought about window film in the past. If it was purely down to me, I would have gone for it, but others were bothered by the aesthetics. Having said that, these days my eyes seem to be getting dimmer, so that might be a consideration with reduced natural light.

I remember when we had a hot summer a couple of years ago, people seemed to moan endlessly about not being able to sleep at night. But when it came to actually thinking of solutions, there seemed to be very little interest.

 

[JohnD]

I once read about a way of designing houses to keep them naturally cool, so that air is drawn in from downstairs and then it vents the hot air somehow out of the top. But I can't remember what it's called.

Loft hatch.

 

[JonathanM]

Loft hatch.

What is the thinking behind that? On a hot summer day, our loft seems to be massively hotter than the upstairs. It feels like the sunlight is being absorbed into the roof tiles and is being radiated into the loft space.

In fact, when I have opened the loft hatch previously in a hot summer, I can actually feel the heat coming down from above on the top of my head.

EDIT: I have just been reading that if your loft is insulated between the joists, then opening the hatch can actually make the rest of the house hotter. That would explain my own observations.

 

[JohnD]

Hot air rises.

If you open the loft hatch on a sunny day, and a door or window downstairs (not on the sunny side) there will be a terrific airflow up, and out through the eaves.

If there is no open door or window you will get a lesser airflow from natural ventilation, gaps and draughts.

 

[JohnD]

EDIT: I have just been reading that if your loft is insulated between the joists, then opening the hatch can actually make the rest of the house hotter. That would explain my own observations.

I wonder where you read that.

Hot air does not descend.

 

[bernardgreen]

Hot air does not descend.

it can happen that wind blowing into thr eaves will push hot air down through the loft hatch

 

[Mrs Ten Names]

I wonder where you read that.

Hot air does not descend.

Convected hot air does not, but radiated and conducted heat in the air does.
Plus the movement of the opening hatch will cause air disturbance at that point.

 

[JohnD]

How would you describe the airflow through your hatch?

I would describe mine as a breeze on a sunny day, and a strong wind if you open the front door in hot weather.

No risk of hot air drifting down.

 

[JonathanM]

I wonder where you read that.

Hot air does not descend.

Does opening the loft hatch help lower the temperature indoors?

I have started to open the loft hatch in our three-bedroom house, the logic being that the hot air has somewhere to escape - but I don't know if it is really helping. Is it a good idea?

www.thisismoney.co.uk

A spokesperson for the Green Age replies: Opening the loft hatch might seem like a quick fix to your hot master bedroom, but is only really an option if your loft is insulated between the rafters. If your loft is insulated at joist level, then you may find that opening the hatch only causes the even hotter trapped air to circulate.

 

[JohnD]

you may find that opening the hatch only causes the even hotter trapped air to circulate.

No, I don't find that.

What did you find when you tried it?

 

[Mrs Ten Names]

It will also increase the risk of condensation in the loft.

 

[JohnD]

You haven't see the amount of airflow rushing out through the eaves. Or noticed that the roof is hotter than the house, which is not conducive to condensation,

It's great to hear from people who've actually tried it. Have you?