House Cooling ideas

[Hecateh]

This time last year no one would have been worrying about this.  It would be nice (in some ways) but unusual if we have this problem for a couple more months.  

 

In my current house my bedroom is to the north so is generally cooler than the living area - but I like to sleep cold .  I like 14 to 16 degrees and use a fan at night frequently.  Being just me I can have all the house doors open and windows open on all four aspects.  

 

For many people, at night, the issue is getting to sleep not staying asleep (not for me, I wake frequently but when I was younger I didn't) So - very damp flannel in hand; fan on; wipe face, neck and arms (and other areas if required) with wet flannel (doesn't need to be cold).  Lie where fan cools your skin, when feeling slightly cold, pull over a sheet or empty quilt cover and go to sleep.  Wet flannel stage may need repeating a couple of times if very hot.  

 

Used it all the time on kids when I was nursing.  Flannel was actually wet with warm water as cold may cause shivering which raises temperature.  

 

I know this is about house temp but sleeping is VERY important

Edited July 11, 2018 by Hecateh

[Dreadnaught]

13 hours ago, JSHarris said:

I know others that have built passive houses that have found that theory doesn't translate well into practice, and have had to take some additional mitigation measures in order to avoid overheating, which in some ways is reassuring. 

 

 

Yes, I agree. I have come across two recent examples of well-inslulated recently finished builds that are overheating. One was modelled in PHPP and one was not. 

 

Some don't take overheating seriously enough at design stage. The 10% of annual hours over 25ºC that is part of the passive-house standard is, in my and many other people's views, far too high. I would like to see a limit of 5% or even 2%. For me, passive house is foremost about making a lovely comfortable home. Time over 25º, let alone any time near to 30º, needs to be considered and minimised. 

 

Working through PHPP for me has been a revelation. As the saying goes, "all models are wrong, but some are useful". I have found PHPP to be immensely useful in making me think about the things that are important. I had read about PHPP extensively before modelling my own house. Even so it has exceeded my expectations.

 

Edited July 12, 2018 by Dreadnaught

[MikeSharp01]

50 minutes ago, JSHarris said:

the provision of hot water

IS that a case of Combi boiler / in-line instant heaters then or perhaps a SUNAMP or similar could do it. You have Sunamp and in line heaters yet you seem to be saying you still struggle. What would you do differently for the provision of hot water or are you just flagging it as one of the two main issues to worry about?

[Jeremy Harris]

44 minutes ago, MikeSharp01 said:

IS that a case of Combi boiler / in-line instant heaters then or perhaps a SUNAMP or similar could do it. You have Sunamp and in line heaters yet you seem to be saying you still struggle. What would you do differently for the provision of hot water or are you just flagging it as one of the two main issues to worry about?

 

Our problem was before we removed the original thermal store (which in theory, and according to the flawed manufacturers test data had a low heat loss) and replaced it with the Sunamp PV.  The primary reason for replacing it and fitting the Sunamp PV was to remove the undocumented massive heat loss from the thermal store (it's documented BS test heat loss was about 1.5 kWh/day, without the additional insulation layer, it's true heat loss was well over 3 kWh/day with an additional layer of spray insulation).

[MrMagic]

Not the most eco-friendly option (depending on where you buy your leccy from) - but mini-split air con units are the best money I've probably ever spent. All bedrooms fitted with them back to a single outdoor unit - the only drawback being that they can only do one function at a time (all cooling or all heating).

 

Budget approx £1000+vat per room inc fitting.

[RandAbuild]

Having moved in just as this hot spell started, this is a very timely thread!

I'm investigating adding reflective film to the outside of our south-facing windows to reduce solar gain. The problem is the sun heats up the internal fabric, and in a well insulated, airtight house the heat has nowhere to go. Fortunately we have 6 Velux windows which are great at venting the heat, but it then has to be replaced by cooler air which means opening ground floor windows. What do you do to maintain security then?

Has anyone (I know Jeremy has) any experience of solar film and which one did you use?

[MikeSharp01]

2 minutes ago, RandAbuild said:

opening ground floor windows. What do you do to maintain security then?

Hence us looking for louvers.

[Cambs]

1 hour ago, MrMagic said:

Not the most eco-friendly option (depending on where you buy your leccy from) - but mini-split air con units are the best money I've probably ever spent. All bedrooms fitted with them back to a single outdoor unit - the only drawback being that they can only do one function at a time (all cooling or all heating).

 

Budget approx £1000+vat per room inc fitting.

 

We did the same on our last self build - rooms in roof and conventional insulation meant that the bedrooms got really hot. Put in split a/c units and they worked a treat but an expensive fix that I’d rather have avoided.

 

Next build has no gas so possible solution being considered is an ASHP with a cooling function.  Cool the UFH in the slab downstairs and might go for fan coil radiators (e.g Panasonic Aquarea air radiators) for upstairs to cool.  Hopefully won’t need it because next roof will be cellulose insulation so should perform better in hot weather.  All still to be decided though. Still got to sort out shading etc.  

Edited July 11, 2018 by Cambs

[Ferdinand]

2 hours ago, Hecateh said:

This time last year no one would have been worrying about this.  

 

Ahem, (said the elephant) . OK ... nearly this time last year.

 

It is is actually quite interesting how the conversation has moved forward. I am managing better this time by more thorough stack ventilation whilst having a 6am breakfast. Being still unable to sleep properly after my hospital episode has at least one advantage. ?

 

 

 

Edited July 11, 2018 by Ferdinand

[Ferdinand]

41 minutes ago, RandAbuild said:

Having moved in just as this hot spell started, this is a very timely thread!

I'm investigating adding reflective film to the outside of our south-facing windows to reduce solar gain. The problem is the sun heats up the internal fabric, and in a well insulated, airtight house the heat has nowhere to go. Fortunately we have 6 Velux windows which are great at venting the heat, but it then has to be replaced by cooler air which means opening ground floor windows. What do you do to maintain security then?

Has anyone (I know Jeremy has) any experience of solar film and which one did you use?

 

 

The first thread I just linked has all the info and links in it.

[lizzie]

9 hours ago, RandAbuild said:

Having moved in just as this hot spell started, this is a very timely thread!

I'm investigating adding reflective film to the outside of our south-facing windows to reduce solar gain. The problem is the sun heats up the internal fabric, and in a well insulated, airtight house the heat has nowhere to go. Fortunately we have 6 Velux windows which are great at venting the heat, but it then has to be replaced by cooler air which means opening ground floor windows. What do you do to maintain security then?

Has anyone (I know Jeremy has) any experience of solar film and which one did you use?

I have huge overheating problems and I am single storey. High on a ridge and open to the elements no trees etc.  My big south and west facing sliders are opened up at 6am every day.  I have big garden parasols outside as temp shading. I keep some of the east side windows wide open too so I have a through draught right across my open plan living area. I close the windows when we go to bed but I keep the en suite open on tilt and the bedroom (west facing)  slider open but locked at about 2 inches to give air without anyone being able to get their arm in.  I have blinds at the bedrooms but not at the big living sliders. The internal blinds help with shading but not hugely with heat, External blinds are not really an option now our building is finished. We would have major problems with getting power around...I. consulted our electrician and carpenter and both said not easily done.

 

 

 

I have been getting quotes for the film but have not gone ahead as I have been trying to find out about using it on 3g laminated.  The spec only reads for 2g and the one supplier says it will be fine......another specialist company locally have looked at my window spec and said they dont recommend film. They would be relcutant to do but if I went ahead then I would have to sign a disclaimer. They say the risk of the glass cracking is very high. They actually took the trouble to look at my glass spec properly the other company have not hence just sending a quote based on my measurements and my intital enquiry.  They are the ones who only had 2g in the spec sheet but said it would be fine for 3g.  I dont trust that I dont think they have properly looked at my window spec.

 

Mine are laminated in and out with the third middle pane not laminated. Be careful if you have laminated windows to my spec is the message.

 

My search for a solution is ongoing meatime I am praying for rain/cloud just for some respite.

Edited July 12, 2018 by lizzie

[Onoff]

Money no object you could perhaps retrofit the "photochromic" glass as one person has done on here already. Not sure that's the right word but they will darken at the touch of a button and are linked to light level / temperature sensors.

 

£Ks per sq. metre I believe though.

[lizzie]

@Onoff if money were no object........LOL

[SteamyTea]

13 minutes ago, lizzie said:

I have been getting quotes for the film

DIY one window yourself and see what difference it makes.

Or just move to the coast.  No real problems here 

[lizzie]

@SteamyTea moving home to the coast (Wales) is long term plan when work life is over.  Wont have same problems there for sure......

 

Advice of film specialist who did not recommend film for my windows was to cool the house as much as possible by whatever means (portable aircon if nec) get through the hot spell and live with it for a year see how things are. As he said this weather is extreme and it may not occur like this again for another 10 years....by which time I will probably be mad or dead. LOL

[SteamyTea]

34 minutes ago, lizzie said:

weather is extreme and it may not occur like this again for another 10 years

Every year, when we get a few sunny days, we have the same conversations about over heating.  We do the same when we get a cold week too.

It is easy enough to do an estimate of extreme temperatures, but they don't correlate with time of year too well.  This ear we had the cold spell in March I think, may have been April.

But I think in your case you have a more fundamental problem caused by too much glass area, that is not going to change.

A quick look on ebay and you can get some delivered for a few quid.  Got to be worth a go as this is a problem that is not going to go away, just hide itself for 50 weeks of the year.

Edited July 12, 2018 by SteamyTea

[Jeremy Harris]

10 hours ago, RandAbuild said:

Has anyone (I know Jeremy has) any experience of solar film and which one did you use?

 

We used two different films, one primarily for privacy on the large glazed gable, that works like one-way glass, at least during the day and one very slightly tinted film on an East facing bedroom window that had more solar gain than the models predicted (we get a surprising amount of sun from the East, far more powerful than that from the West, another local effect to do with haze build up in the afternoon, perhaps from the stream and lakes adjacent to the house).

 

The front glazing film is Sentinel Plus Stainless Steel  and the side glazing film is 3M Prestige .  If not interested in privacy control, then I'd use 3M Prestige , as you will hardly know it's there.  It is more expensive, though, and generally I'd avoid using an external film unless you have other options.  In our case we had an unforeseen privacy problem at the front, so films made sense.  If we hadn't had that issue, then I'd have been inclined to look at something like the timber brise soleil slats discussed in this thread, with some photos on the second page:

 

 

[joe90]

50 minutes ago, lizzie said:

this weather is extreme and it may not occur like this again for another 10 years....by which time I will probably be mad or dead.

 

I agree, I have been told by many that when my conservatory is built (on the South side) I will get massive overheating problems but we are having solar glass in the roof to try to stop it. It’s a little like my heating strategy, no heating upstairs save bathroom towel radiators, yes I might need electric heaters in the bedroom for a few weeks of the year but so what, I am not having a heating system in rooms that are ok for say 40 weeks a year! Likewise I am not having a cooling system (other than reverse engineering my ASHP UFH which already exists) for a few hot weeks a year.

 

people jet off to the sun for a holiday for these temps.

Edited July 12, 2018 by joe90

[Gone West]

14 hours ago, JSHarris said:

You can get solar gain right down, as we have, but that doesn't overcome the fundamental problem of outside air at 30 deg C + during the day, and maybe 20 deg C+ at night (we've had four consecutive days where the night time air temperature was over 23 deg C).

 

That is why modelling the climate data correctly for where you live is so important, as I have mentioned in the other thread. Over the last month or so our maximum night time temperature has been 17C, which was on one night only, it's usually around 14C. The maximum daytime temperature has been 27C which again was on one day only with most days being around 23C. There is usually a strong easterly sea breeze every afternoon here, which has the effect of keeping the air cool in the shade.

[Jeremy Harris]

The lack of any breeze at all in this hot weather has had the most impact, I think.  It was notable when I went back down to Cornwall last week and the week before that it was noticeably cooler, primarily because of the constant breeze I think.

[joe90]

7 minutes ago, JSHarris said:

The lack of any breeze at all in this hot weather has had the most impact, I think.  It was notable when I went back down to Cornwall last week and the week before that it was noticeably cooler, primarily because of the constant breeze I think.

 

I agree, here on the north Devon coast we almost always have a breeze, if not , very windy, and the odd day we have no breeze the difference is massive. On still days it’s good to be working indoors.

[Hecateh]

11 hours ago, Ferdinand said:

 

Ahem, (said the elephant) . OK ... nearly this time last year.

 

Most years recently though it has been a few days - not a few weeks like this year ?

[newhome]

20 minutes ago, joe90 said:

 

I agree, here on the north Devon coast we almost always have a breeze, if not , very windy, and the odd day we have no breeze the difference is massive. On still days it’s good to be working indoors.

 

Agreed. I’m on the coast and generally there is a more than healthy breeze. It’s been so still here recently it’s been impossibly hot - in Scotland - unheard of! 

 

[newhome]

2 hours ago, lizzie said:

I have huge overheating problems and I am single storey. 

 

This may be irrelevant but a couple of houses ago I had a house with an almost flat roof. I think yours is too? Mine was 2 storey and the upstairs was unbearable in very hot weather. Downstairs was fine (same size glass installed up and down pretty much). It was an old house so won’t have been built to the insulation standard of yours clearly but I’m just throwing it out there in case some of your issue might be caused by your roof. 

[Jeremy Harris]

The main problem with rapid overheating is caused by a short decrement delay.  Get this long enough, and combined with cool nights and a night purge system you can usually keep a very well insulated house cool.  The exception is prolonged hot weather and warm nights, when a night purge has little effect, so the internal temperature builds up day on day during a hot spell.