Keeping house cool in summer re. insulation

[adamr7747]

Hi All,

I have an old house with solid walls (stone downstairs, 1 brick thick upstairs) and 100mm of existing loft insulation. The upstairs turns into a sauna in the summer. At some point in the future I will be thinking about how to insulate the walls but, for now, I'm just about to top up the insulation in the attic. I'm wondering if there are any issues specific to keeping the house cool which I should consider. I've bought a load of the 200mm B&Q recycled glass wool insulation which they're doing for £1 per square meter at the moment. This doesn't have a "reflective" layer like some of the more expensive blanket and I'm wondering if this matters? Should I lay some of the shiny bubble-wrap stuff (like this) between the old and new blanket? This would mean doubling the amount of money I've already spent on the insulation.

Following a bit of googling, I've also found some references to "radiant barriers" which would mean stapling the bubble wrap to the underside of the rafters (I think)? Is this the right thing to do - the websites talking about it mainly seem to be in considering US houses with A/C.

I'd be grateful for and advice/thoughts/comments?

Cheers,
Adam

 

[freddiemercurystwin]

Adding a layer in between the insulation will do little to improve the heat loss. 3 layers of mineral wool (your orig + the 2 new ones) insulation will be fine. Ensure that your eaves are well ventilated, make sure your new insulation does not block the ventilation, under no circumstances should you be adding a layer of anything to the underside of the rafters. Your insulation 'bubble' will be at ceiling level, everything above that should be open to the atmosphere and well ventilated to ensure there is no condensation build up. Whilst insulation certainly helps keep a house warmer in cold weather it should also have the opposite effect in warm weather however IMO it is rarely as effective at keeping the heat out as it is at keeping the heat in.

 

[adamr7747]

Whilst insulation certainly helps keep a house warmer in cold weather it should also have the opposite effect in warm weather however IMO it is rarely as effective at keeping the heat out as it is at keeping the heat in.

Hmm, shame. Does anyone else have experience relating to loft insulation keeping the house cool in summer? My logic is that the reflective stuff might stop radiation from the hot attic into the house below. Presumably the blanket will stop conduction and convection shouldn't work downwards...

Adam

 

[big-all]

opening windows and allowing cross air flow will make a lot more difference when trying to cool than extra layers in the loft

 

[lofthelp]

go to b@q and buy insulation foil rolls there only £9.96 per roll thats less than half price and staple them to your rafters.

if you roll them over your rafters and seal, that hot sun will bouce right back of and hopefully come to my back garden because we dont get much sun here.

give them a try the keep your house cool in the summer and warm in the winter.

 

[adamr7747]

opening windows and allowing cross air flow will make a lot more difference when trying to cool than extra layers in the loft

Thanks, we've tried that already!

 

[freddiemercurystwin]

opening windows and allowing cross air flow will make a lot more difference when trying to cool than extra layers in the loft

Thanks, we've tried that already!

I think you're missing the point of big-alls post, he's saying that opening the windows will make more difference than insulation alone so don't go expecting magic results by adding more insulation in the loft with a layer of bubble wrap or no layer of bubble wrap.

If you think about it its easy to understand, during the winter you are trying to keep a small bubble warm when surrounded by a huge amount of coldness using heating devices such as radiators.

During the summer you have no such devices working inside the bubble keeping it cold hence keeping it cooler in the summer is harder. That's why air conditioners are popular overseas.

Adding insulation to the walls may help a little although the same thing applies.

You can try using a few fans to get more airflow but there is no magic solution other than air conditioners which obviously have their downside in £££s.

 

[adamr7747]

Oh, OK, I see what you mean. It's a shame every website in the world says "and keeps your house cool in summer" when talking about insulation!

However, I do wonder if my house is particularly prone to over-heating due to the poor existing insulation - it seems to get much much hotter than other houses in the hot weather.

Adam

 

[big-all]

go round the house count how many mains gadgets are turned on like tvs games consoles ect

count how many spots and normal 60 or 100w bulbs you have burning away
place a thermometer in the shade out side then in the house if the outside temperature is greater than indoors shut the windows and doors if its less open the doors and windows

if you are trying to cool down the upstairs keep the doors shut down stairs and open the doors and windows upstairs

you will find the upstairs is a few degrees hotter as hot air rises

 

[freddiemercurystwin]

However, I do wonder if my house is particularly prone to over-heating due to the poor existing insulation - it seems to get much much hotter than other houses in the hot weather

Some house are more prone to overheating than others, as a general rule masonry houses stay cooler in the summer, big thick stone walls are the best. Unfortunately you are right down the other end of the scale in terms of keeping excessive heat out in hot weather with thin timber frame construction. Adding insulation will help a bit but not a lot.

 

[IJWS15]

I would not want a vapour barrier of any kind in the loft insulation unless the loft is not ventilated (it should be).

In summer close the curtains on the sunny side of the house - older houses can have large windows and the sun is the biggest free heater we have access to and as sods law states - it works better in summer.

Let cool air in early in the morning and then close most of the windows to keep the cool in and the warm out.

Think about how many appliances you have on.

Energy saving light bulbs.