Why is it so hot inside my house?

[Mr B]

The most frustrating thing is that when the external ambient air temperature cools down (or at night), the internal air temp seems to rise! :-(

The house is an 1800s end-terrace with (solid) walls, white-rendered at the south-facing front, and it becomes incredibly hot during these spells of hotter-than-normal weather. The 1st and 2nd floors are much warmer than the ground - thankfully the basement remains at 20 deg or below. The 2nd floor's pitched roof is insulated both under the felt and above the ceiling joists. I've tried covering a large section of the end wall with insulated plasterboad but this doesn't seem to have made any difference.

Any ideas? Or does the large amount of solid brick wall mean that I'm condemned to very slow changes in temp?

[Guy King]

The message from Mr B contains these words:

Leave the loft hatch open in hot weather. Makes quite a difference here.

[sm_jamieson]

Well, hot air rises to the top of the house, so it's not surprising. Temp rises at night - electric light bulbs pumping out heat ? You need windows open downstairs and a ventilation system that pulls air up the house and out of the roof in order to cool things down at night. And what loft insulation does the loft room *actually* have ? White rendered wall ? Should help to keep heat out. Simon.

[sm_jamieson]

I used to open the loft hatch at night. But I think the OP has a loft room. Simon.

[meow2222]

Lots of thermal capacity is a good thing, insulation is better on the outside. When you rerender one day, then you can insulate at the same time.

Night time temp is below daytime, so copious ventilation at night will gradually cool the structure, and that coolth is stored into the next day. IOW it indirectly causes cooler days. Locking all the windows 1/2" open at night helps, adding fan ventilation helps more.

There are threads on this sort of thing, check google ukdiy archives for more options.

NT

[Guy King]

The message from "sm_jamieson" contains these words:

So leave the rooflights open!

[David Hansen]

On Tue, 13 Jun 2006 10:59:08 +0100 someone who may be Mr B wrote this:-

Passive ventilation. Have some windows slightly open at the top of the house and the same at the bottom. The gentle current of air will keep things nicely cool. Any accessible windows need to be locked.

Properly designed vents can do the same thing.

[charlieB]

Yes - we have a similar problem in a similar property - seems a bit like living in a large storage heater in the current weather

[sm_jamieson]

Maybe it's the direct sun heating up the wall. Insulation on the outside would help to reduce this effect, whilst maintaining the advantages of the thermal mass effect. Simon.

[Helen Deborah Vecht]

"sm_jamieson" typed

My house is cerainly not any cooler overnight since the wall cavities and loft were insulated. :-( It's a 1930's red brick semi, with a dark roof. It's intolerable overnight at present.

[sm_jamieson]

I think its just that the hot air gets trapped in the rooms and stays there. If there was a massive fan sucking air out of the roof, grilles in all the ceilings and the downstairs windows open, it would soon cool down. The higher the ceilings the better, since you tend to get a layer of hot air up their. I was fixing some plumbing up by the kitchen ceiling the other day and the effect was quite pronounced. Simon.

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Mr B saying something like:

That's about it, really. I'm cursed/blessed with 10" thick solid walls too.

One thing you could do is to clad the outside with 2" of foamboard and render, to cut down the heat soak. Allied with improved ventilation, this would probably provide a solution.

The other side of the coin is, in wintertime your walls will absorb a fair bit of heat and keep your internal temps reasonable.