To ask how are people not dying in new builds with the heat?

[icantbreathehelp]

Our new build is a fu..ing joke!! We are actually going to have to sell our house before next year or live downstairs because it is so hot upstairs at night that a newborn baby would over heat and end up in hospital without a doubt!

How the hell are people coping with the heat in new builds? We live in a redrow house, we have to shut all the blackout blinds at the back and open all the windows at the front and even with 2 metal fans on its still like sitting in a sauna! I don't want to go to sleep because I am scared DC is going to over heat.

I cant cope 🥵🥵🥵

Have you got a velux or something for the hot air to rise out of?

New build here. Lovely and cool! Winter? Fuck me it’s like living in a igloo with the door open. It’s unberably cold.

I complained to my housing association after moving in, who checked somehow with the builders, and all the specs said that my flat was only at 'moderate' risk of overheating. Apparently that means it's OK to build it like that. What actually happens doesn't matter to them.

They said in the specs it has cross ventilation. It doesn't really. And the road is very busy and polluted and noisy, so there's a limit to how much you can keep doors and windows open, and as it's ground floor, you can't really at night.

I'm trying to shade the windows a bit from outside. Does anyone know if frosted glass absorbs as much heat? Some of the windows are frosted, and I wonder if I"m better arranging the (limited) shading to screen the clear glass bit most, as I'm sure that must absorb more heat into the house than the frosted.

The bedroom is about 29 now, which is better than last year, so maybe the shading helps a tiny bit. Or maybe it's just that it's not as humid as sometimes.

Those portable air cons that vent out the windows, I'd need a big sealing kit as I have the windows that hinge at the top and open outwards. Would the sealing kits provide any sort of security that would allow them to be used at night on the ground floor? Or is there some sort of window restrictor, like a child lock or something, that could hold it open wide enough for the hose, but not let anyone break in? I guess they'd have to be key operated or something, as you could easily get a hand or tool in otherwise, to open whatever sort of lock or restrictor there was. Wouldn't be great from a sound or pollution point of view either I suppose.

You've got to block the air coming in when it's hotter outside and yes block the sun. Reflective or blackout blinds if you can't install shutters. If a heatwave isn't a good reason to buy new blinds (fair) use cardboard or MDF to block the windows instead.

It's a bit dramatic to say that DC are going to overheat so you can't sleep for worrying and a newborn baby is going to die. Babies have been born for millennia in much hotter countries than this long before air conditioning was a thing. As long as the bedroom isn't 40 degrees or something the children might be a bit uncomfortable but they are not in danger if dressed lightly.

People in the UK can't seem to get past this mental block of needing to close the windows to keep the hot air out. It's like open windows somehow magically make it cooler even when it's hotter outside I do understand the reticence but it does actually work, so it's worth trying. You can get a really cheap indoor/outdoor thermometer on amazon, that's invaluable for use with this technique.

Have you got a velux or something for the hot air to rise out of?

Yes it's been open all day. Sleeping in the spare room tonight me thinks 😬

Our new build is fine....we moved in 12 months ago.

I think it helps that the upstairs only has one window that's south facing and we keep that shade down permanently when it's hot.

Others we keep at least partially down during the day.

Tricky about air con needing to vent on ground floor. Not v good design not to be able to open windows in a secure way. I must admit this is one of the things I like about living on the fourth floor - we can leave our windows and balcony door wide open with no security issues at all.

This kind of thing is meant to be a bit more secure and you can get extenders for bigger windows.

www.amazon.co.uk/AWK01-Airo-portable-conditioners-Installation-9001690529-White/dp/B07D16JDBF?tag=mumsnetforu03-21

If you keep your windows shut all day doesn't it make it stuffy inside?

Downstairs

Open all windows and doors all day every day.
Before I go to bed I put the kitchen window on the latch (front of the house) and leave the lounge window open as that's at the back and not accessible or in view of anyone apart from neighbours. Close front and back doors.

Upstairs

In the daytime I leave windows open and close the blinds
Night time I open the blinds and keep the windows open

I also have fans in the bedrooms for night time, place them in front of the open windows and peg a damp tea towel to them.

I'm a bit sad about all the people suggesting air con - the point of the insulation is to reduce carbon emissions from heating.

If we all start switching to using air con because of two or three hot days then it sort of defeats the purpose

the portable air conditioners usually have a hose like a tumble drier to blow the hot air outside.

It needs a hole very like a small extractor fan uses in a bathroom, or a cooker hood, about 110mm

If you're on the ground floor it would be safe to drill one, but the building owner might object. If you are particularly lucky there might already be one. Plumbers and builders use a Core Drill to cut these round holes, there is no hammer and chisel work needed these days. The hole should be fitted with a plastic liner and an outside grille to prevent wildlife or rain entering, and to prevent CWI or dust falling out.

The drills are rather dusty and noisy. If you ever hire one, you will enjoy it so much that you drill extra holes for extractors and tumble driers, ready for future use. They are too heavy and powerful to be safe working off a ladder.

The same way anyone does. Blinds and windows all closed during the day to keep the sin out, fans moving the air about and then windows/doors open when it starts to cool down and over night.

Have spent a lot of time on building thermodynamics recently.

Here is my learning...

Insulation is definitely not the problem. Super insulated passivhauses are actually great for reducing overheating.

Windows are the problem, in particular sun coming through the window. Shading needs to be EXTERNAL. So shutters, awnings or external blinds. Use cardboard or stick blackblinds on the outside of your windows as a temporary measure. West and south facing windows, or roof lights are the biggest issue. Internal curtain blinds are much, much, much less effective.

Only open windows if they are in the shade. Opening on the sunny side will heat the house.

Use fans to create a cooling breeze. Don't create a through breeze by opening a window on the sunny side.

Make sure all roof lights are open overnight and one window as low down the house as you can without causing a security issue.

With a super insulated new build you should just be able to 'night purge' by opening windows, then shut all windows during the day as long as they are externally covered and have a cooler house than you can get by having any windows open during the day.

I don't think the building owners would let me drill. And I'd need to move it from the main room to the bedroom, unless it's enough to cool both spaces.

The window kit linked above looks interesting, but wouldn't work with my sort of windows - they are awning windows, hinged from the top. yes, very bad design for ground floor, really. I did find one sort of sealing kit but it was huge and needed sticking on around the whole thing, would be a pain to take on and off, and still not secure at night unless I had a bar of some sort as well.

I wouldn't switch to air con for two or three hot days, but last summer I had a couple of months where the internal temp wasn't below 27 or so, and many days it was above 30.

I'm hoping the shading screens/umbrellas would help more, but I'd have to get more. There are some trees planted but it'll be quite a while before they're big enough to give much shade.

We have MHVR units that bring ventilation in, but it doesn't provide any cooling. It does mean that there are pipes and vent holes above the ceiling somewhere, but I don't think I can access them in order to fit air con. Would be v handy if I could though as it would look much better. There is also an extractor fan but I have no idea how that vents out!

I don't really want to have to use air con, but at the same time, I do have to sleep. So I'm trying the other solutions first. Might investigate external shutters, but they can cost thousands. I also need to be able to see out to an extent so wouldn't want them up all the time, but there are adjustable ones that would help.

When its really hot its best to keep the windows closed and use a fan to move air about. If its 30deg outside and you open the window its going to become 30deg inside too.

If you have an MVHR, have you checked that it is properly set to summer bypass mode? Some do it automatically some don't. That could be a big issue of it isn't. You also don't want it to boost during the day as that will send hot air into your house. It may be contributing quite a bit towards your issue.

If you boost overnight it will help with the night purging.

Depending on who supplied your MVHR, you can get a cooling system to integrate with it. Not as powerful as AC but would help a bit.

No more stuffy than in winter when you have the windows closed to keep out the cold. And much less stuffy than being hot.

The windows have been closed all day in this house (east/west) London semi and it is beautifully cool indoors. Outdoors is like walking into an oven. Indoors is fine. The one room where the window was left open by mistake for ages (the shower room) is now extremely muggy. QED

The coolest room in this house is the downstairs loo!

How hot exactly is it inside the house?

yes I have it on summer bypass and on boost at night. The summer bypass is automatic, and the boost I control on the whole, though I think it comes on for a short time if it detects higher humidity. I can also change the settings for intake and output etc ,and I think they're on 100% in the summer. I can open/close the vents slightly too, as in the winter ,it's sometimes too chilly if they are blowing right on me, even though I welcome the fresher air (very polluted street)

I enquired about the cooling system for MVHR, but was told it was for much bigger units. Mine is small as it's for a one-bedroom flat. I'd love it if they made one that would work with that! Maybe it will still be developed. Mine is a Greenwood Vireo one. Do you know who made the cooling units? The one I enquired about was Zehnder, ComfoAir or something like that. But it was for much larger, whole house systems. Mine has to fit in a little cupboard, though I'd happily give up half the cupboard to that if it actually worked to provide extra cooling, even if it's my only storage space.

New build town house..... Ceiling fan

More I think about this the more I suspect your MVHR is still heat recovering even though it is summer. That would explain why you are struggling to cool it. Have you got the manual? If you want to PM me a make/model number I might be able to help. They are a relatively new thing and so it can be tricky to understand what needs doing with them.

We’ve had all curtains and windows shut today. The house has reached a peak of 24 degrees while at the same time being 34 degrees outside.

Keeping your windows shut is the key. It’s somewhat counterintuitive I know but when you think about it logically it makes sense. Why would I let 34 degree air in when thats much warmer than what I’ve currently got inside.

My Italian neighbour has done the same today but it looks like we’re a minority in our road! Try it, it really works.