If you have internal wall insulation, are your bedrooms too hot in summer?

[PandoraRocks]

I've got to renovate my house and wondering if I insulate the external walls will my bedrooms be too hot in summer? I've got to do some rooms such as the lounge as it's large and freezing.

I can't comment explicitly on wallinsulation, but when I had roof insulation added (from barely there to the recommended ??10 inches??) it made things much warmer in winter, much cooler in summer, and the temperature change was much slower.

I assume while the insulation is intended to stop the hear escaping in winter, it also stops the heat travelling in the other direction when it's hot.

Insulation keeps rooms cooler in summer. It stops heat travelling in both directions.

So do you think that putting a thick heavy coat on a snowman would cause it to melt faster or to stay longer on a sunny day?

Yes@larkstar I know the theory. It's just that I have read on mumsnet people complaining their new build insulated houses were so hot upstairs 🤷‍♀️

If I had to make a guess- and that's all it is, a guess- it woud be that a lot of modern houses are not designed to have what I would call enough ventilation. All insulation does is stop heat crossing it. If it gets hot inside, it will stay that way unless you do something about it. So if you have lots of insulation, in summer you need to ventilate like mad overnight when it's cooler- as heat will get into the house through doors during the day (and windows , if you don't have blinds).
We need to learn from our neigbours in warmer countries- in the summer, close blinds shutters and curtains in rooms whilst they are facing the sun. When it's cooler outside than in, open the windows. In our house, sometimes it's cool outside at the front when it's hot at the back! Then the insulation will be a help and not a hindrance.