How do you keep your bedrooms cool (if indeed you do!)

[Norbert]

We are planning a ultra insulated air tight house with UFH, ASHP, MVHR blah de blah.....

 

However I see an issue looming, how do we keep the bedooms cold enough? We have always had bedroom windows open all winter with no heating in the bedroom, it is just the way we like it, it seems healther and we sleep better. Bedroom temp of say 15/16C seems ideal, while all other rooms are nice at say 20/21C. Given that the bedrooms would be inside the super insulated efficient thermal envelope, and the MVHR would be purring away it seems to me likely that the bedroom temp will be around 19/20C. Indeed I was speaking to someone recently who had recently moved into a new house and the biggest problem thay had was keeping the bedroom cool enough, while all other rooms were warm enough.

 

So I was thinking ..... maybe not have an MVHR plenum in one of the bedrooms, no gap under the door, trickle vent on the window, plus opening window with NE aspect so minimal thermal gain, insulated internal walls etc. So just a partial MVHR? There will be 2 double bedrooms so the other could have UFH, MVHR etc. and we could use that in very cold weather or when we get older and want it warmer.

 

Does anyone else have this issue and how do you solve it?

 

 

 

[JohnMo]

MVHR doesn't move much heat around.

 

We are in a bungalow with all the above, just keep the bedroom doors closed and don't heat the room much. It's then colder in the bedrooms. Want to even the temperature up, open bedroom doors.

 

In summer we open the bedroom window and run the UFH in cooling mode when we get most solar gains.

[Conor]

Our rooms are all 20-21c. No complaints. Light summer douvets all year round. Stop overthink it.

[LnP]

This is a good question and I'm also interested. My wife's view is that the bedroom is too warm if you can't see your breath!

[ProDave]

We don't have heating upstairs, not needed.  When the heating is on, we keep the bedroom door shut to stop heat rising by convection.  You can still open the window of you want to cool it down more, mvhr does not prevent that, but having mvhr means it is not necessary to open a window to get fresh air.

[SteamyTea]

The biggest problem is going to be the warmer months.

Changing the air 0.5 times an hour, or 10 times an hour, via MVHR or not, is not going to help if the OAT is close, or above your ideal temperature.

You may have to factor in some cooling.

 

Personally, having grown up in the tropics, I like a warm bedroom. It can take a few weeks to get used to it, but then I sleep as well as I ever do. And getting up to a warm house is lovely.

Edited October 27, 2023 by SteamyTea

[ProDave]

Keeping a room cool in hot weather, we achieve by a "night purge"  Keep the windows shut in the day to keep the heat out, and as soon as it cools down in the evening so it is colder outside, throw all the windows open.

 

That does not help of course if is remains uncomfortably hot overnight, but that is seldom a problem up here.

[Adrian Walker]

Actually it's not always the temperature of the air that prevents you from getting a good night's sleep, it's the quality of the air also.  Low CO2 and Particulate Matter (PM) has a huge influence on your sleep.  Luckily a good MVHR system should help you achieve that.

[Russdl]

14 hours ago, Norbert said:

Bedroom temp of say 15/16C seems idea

I presume you’re snuggled under a quilt with a room that temperature?

 

Without any heating our bedroom temperature is 21.5 degrees, as is the rest of the house +/-0.5. We’re sleeping under a quilt cover (no quilt) and we do so for >90% of the year. It’s like summer night bedroom temperature all year round.
 

I’m guessing that currently you don’t achieve your desired 15/16C in the summer? You’ll adapt. 
 

 

[mjc55]

We too need to answer this question.

 

As the OP we have always slept with bedroom window open and are at the beginning of the design stage of our self-build.  I think the 'air quality of MVHR', 'you will get used to it' etc. comments won't wash with us.

 

It's not that the bedroom has to stay cool all day, quite happy with it being a reasonable temp even when we go to bed, it's just that overnight we want openings of some form!

 

We are planning a single storey build so will have to factor this in to the design process.  Even though our site is in a small village I'm not sure that leaving the window open will be a possibility (we are currently planning french/sliding doors for our bedroom), so we will need to look at a secondary opening of some sort, maybe an opening rooflight!

[Adrian Walker]

1 hour ago, mjc55 said:

We too need to answer this question.

 

As the OP we have always slept with bedroom window open and are at the beginning of the design stage of our self-build.  I think the 'air quality of MVHR', 'you will get used to it' etc. comments won't wash with us.

 

It's not that the bedroom has to stay cool all day, quite happy with it being a reasonable temp even when we go to bed, it's just that overnight we want openings of some form!

 

We are planning a single storey build so will have to factor this in to the design process.  Even though our site is in a small village I'm not sure that leaving the window open will be a possibility (we are currently planning french/sliding doors for our bedroom), so we will need to look at a secondary opening of some sort, maybe an opening rooflight!

"As the OP we have always slept with bedroom window open and are at the beginning of the design stage of our self-build.  I think the 'air quality of MVHR', 'you will get used to it' etc. comments won't wash with us."

 

This is not hearsay, a myth or a legend - the air quality, and in particular CO2 levels, are always far more important than temperature

 

[JohnMo]

4 minutes ago, Adrian Walker said:

"As the OP we have always slept with bedroom window open and are at the beginning of the design stage of our self-build.  I think the 'air quality of MVHR', 'you will get used to it' etc. comments won't wash with us."

 

This is not hearsay, a myth or a legend - the air quality, and in particular CO2 levels, are always far more important than temperature

 

That was way more polite than my draft, which I deleted.

 

Also in a single storey you can close the bedroom door and the room stays cool, has great air quality, CO2 stays below 1000ppm, so doesn't feel stuffy blah blah.

[Thorfun]

I don’t get this. Just open the (expletive deleted) window if you want it open! 🤷‍♂️

 

as @ProDave said having MVHR doesn’t mean you can’t open a window. 

[mjc55]

1 hour ago, Thorfun said:

I don’t get this. Just open the (expletive deleted) window if you want it open! 🤷‍♂️

 

as @ProDave said having MVHR doesn’t mean you can’t open a window. 

 

This is what I am enquiring about!  I am new to MVHR and it's associated uses.  I need to do more research obviously but it seems that this is a good place to do that.  Won't be quite as simple as just opening a window though as we are planning single storey, flat roof and therefore need to probably have some form of rooflight to open. for security reasons.

[Russdl]

9 hours ago, mjc55 said:

I think the 'air quality of MVHR', 'you will get used to it' etc. comments won't wash with us.

Why? Do you think it’s ’Fake News’?
 

9 hours ago, mjc55 said:

it's just that overnight we want openings of some form!

Why? Is it for fresh air? That is what the MVHR does.
 

It also cleans and pre warms that fresh air as well. A bit of a no brainier really. If it’s for the ambient night time noises, well it can’t do that but you could probably use one of the many streaming services to provide that. 
 

9 hours ago, mjc55 said:

so we will need to look at a secondary opening of some sort, maybe an opening rooflight!

Get ‘tilt and turn’ windows that open inwards. When tilted the top is open and it is a perfectly secure way of letting outside air into your home and in my view would be far superior to cutting a hole in a flat roof and plonking an opening window in that with the associated leak risk, rain noise, unwanted solar gain that such a set up could bring. 

Don’t be afraid of new(ish) ways of doing things. Try and work out exactly what you want and why or else you could end up building a one of home to the same standard that the mass build developer achieves and that would be very disappointing   

 

(As per @JohnMo I had to delete and re-write my original response)

Edited December 12, 2023 by Russdl

[Russdl]

5 hours ago, mjc55 said:

I need to do more research

That is exactly what is required I reckon. I suspect you’ll need to drag your other half down the path of learning as well, and you’re right, this is a very good place to start. 
 

Your homework for tonight is to read loads and loads. 

[patp]

We are now living in our, single storey, build and the problem of a hot bedroom is a serious one. We live in sunny Norfolk and, no matter what we do, the bedroom is far too warm at night. I spent all last summer keeping the sun out during the day and trying to release heat at night without sleeping with the windows open. Aside from causing a lot of stress (I am a poor sleeper) it just did not work. We got as far as seeking quotes for air conditioning. If we stay here then that will have to be the answer.

 

I am even considering getting a guarding breed of dog that can sleep in the bedroom with us so that I feel safe sleeping with the windows open! The current Cocker Spaniel just does not cut the mustard 😂

 

Another solution would be to adopt the Spanish system of metal railing type fixings on the outside, and the windows opening inwards. Not sure if that would fall foul of the fire regulations though? Too late for us as the windows are already installed.

[Simon R]

On 27/10/2023 at 15:30, Norbert said:

So I was thinking ..... maybe not have an MVHR plenum in one of the bedrooms, no gap under the door, trickle vent on the window, plus opening window with NE aspect so minimal thermal gain, insulated internal walls etc. So just a partial MVHR? There will be 2 double bedrooms so the other could have UFH, MVHR etc. and we could use that in very cold weather or when we get older and want it warmer.

Our MVHR input is typicaly 1.5-2 C below the output air temperature and as others have mentioned they don't move heat around as much as you might expect. Our build is upside down, with the bedrooms downstairs and this has had more effect than anticipated with a 2 to even 3 degree cooler temperature downstairs in the bedrooms.

 

Heating inputs to a well insulated airtight structure are incredibly low. Have you considered small split air to air AC units to either heat or cool? they provide a very economical and efficient solution. I suspect that in many smaller (ours is 180m2) low energy builds heat pumps and underfloor heating are more than is actually required.

[JohnMo]

39 minutes ago, patp said:

We are now living in our, single storey, build and the problem of a hot bedroom is a serious one. We live in sunny Norfolk and, no matter what we do, the bedroom is far too warm at night. I spent all last summer keeping the sun out during the day and trying to release heat at night without sleeping with the windows open. Aside from causing a lot of stress (I am a poor sleeper) it just did not work. We got as far as seeking quotes for air conditioning. If we stay here then that will have to be the answer

Any area of the world, in summer, you exclude solar gain during the day, close curtains and blinds, as soon as it warmer inside than out, you purge, open windows at either side of the house to promote airflow. You do this with it with MVHR.

 

A2A heat pump can be good for cooling.

 

You don't need dogs that shouldn't exist in the first place, a sausage and nearly all dogs are your best friend. If someone wants in to your house they aren't going to squeeze through a small gap, plenty of other ways in. A couple of outside lights on a PIRs is more than enough deterrent. If it's not, they are coming in anyway.

[MR10]

50 minutes ago, patp said:

I spent all last summer keeping the sun out during the day and trying to release heat at night without sleeping with the windows open. Aside from causing a lot of stress (I am a poor sleeper) it just did not work. We got as far as seeking quotes for air conditioning. If we stay here then that will have to be the answer.

Have you considered external blinds to keep the heat out during the day?

[mjc55]

11 hours ago, Adrian Walker said:

"As the OP we have always slept with bedroom window open and are at the beginning of the design stage of our self-build.  I think the 'air quality of MVHR', 'you will get used to it' etc. comments won't wash with us."

 

This is not hearsay, a myth or a legend - the air quality, and in particular CO2 levels, are always far more important than temperature

 

 

11 hours ago, JohnMo said:

That was way more polite than my draft, which I deleted.

 

Also in a single storey you can close the bedroom door and the room stays cool, has great air quality, CO2 stays below 1000ppm, so doesn't feel stuffy blah blah.

 

10 hours ago, Thorfun said:

I don’t get this. Just open the (expletive deleted) window if you want it open! 🤷‍♂️

 

as @ProDave said having MVHR doesn’t mean you can’t open a window. 

 

4 hours ago, Russdl said:

Why? Do you think it’s ’Fake News’?
 

Why? Is it for fresh air? That is what the MVHR does.
 

It also cleans and pre warms that fresh air as well. A bit of a no brainier really. If it’s for the ambient night time noises, well it can’t do that but you could probably use one of the many streaming services to provide that. 
 

Get ‘tilt and turn’ windows that open inwards. When tilted the top is open and it is a perfectly secure way of letting outside air into your home and in my view would be far superior to cutting a hole in a flat roof and plonking an opening window in that with the associated leak risk, rain noise, unwanted solar gain that such a set up could bring. 

Don’t be afraid of new(ish) ways of doing things. Try and work out exactly what you want and why or else you could end up building a one of home to the same standard that the mass build developer achieves and that would be very disappointing   

 

(As per @JohnMo I had to delete and re-write my original response)

 

Well, certainly seemed to have raised some eyebrows with my post.

 

The fact is that we like to and have slept with open windows in our bedroom for over 40 years, I'm not questioning the air quality of MVHR it's a lifestyle choice.  We are lucky enough to have lived in rural areas for nearly 30 years and so air quality has never been questionable.

 

I will, of course, continue questioning the choices to be made when designing our home, that's the point of this forum isn't it?  And please, you don't have to go easy on me by using a measured response, I won't get upset, honest. 

[joe90]

2 hours ago, patp said:

Another solution would be to adopt the Spanish system of metal railing type fixings on the outside,

Or on the inside 🤷‍♂️ far cheaper solution and saves changing the windows.

[JohnMo]

5 minutes ago, mjc55 said:

The fact is that we like to and have slept with open windows in our bedroom for over 40 year

I also, bedroom window open 24 hrs 365 days per year, no heating in bedrooms. With MVHR, now window open for about 4 weeks in height of summer only. Really don't feel the need at any other time.

 

When we talk about air quality its indoor air quality, in a city or in the country indoor air quality can be good or or bad, it really depends on the ventilation system. Many posts on here talk about mould, condensation, high CO2 in bedrooms etc. MVHR is that magic bullet that fixes those issues.

[Russell griffiths]

9 hours ago, mjc55 said:

 

This is what I am enquiring about!  I am new to MVHR and it's associated uses.  I need to do more research obviously but it seems that this is a good place to do that.  Won't be quite as simple as just opening a window though as we are planning single storey, flat roof and therefore need to probably have some form of rooflight to open. for security reasons.

Modern windows will have a security restriction

 

we are also single storey and my wife was worried about sleeping alone while I’m away, our windows open about 50mm and stop, you need to physically push a button to get them to go further, I have tried a couple of times from the outside to get my arm in and push the button, can’t do it, gaps too small. 

[Alan Ambrose]

Yeah, my other half likes the bedroom super-cool and breezy. Most of the year we accomplish that by simply not heating the bedroom and leaving the window open. It's stuck me that she is a better CO2 detector than I am, but we'll only find that out when we finally have our build done. @Norbert - will you have separate control of the heating in your bedrooms?