Strip off and enjoy while you can!

 

Any excuse for a mankini and sandals, eh?

Gaz

 

Annoying that you can't reverse the ASHP, especially as pretty much all of them are reversible. Ours is currently pushing water at around 12°C around the ground floor slab, with the slab surface sitting at 17.9° as I type this, and the house sitting at 21.7°C.

Most of your heat gain will be via the windows, as I guess you know. The fixes for this range from installing infra red reflective film on the outside of the glazing (we did this a few years ago, very effective), though fitting awnings or something fixed, like a brise soliel, to screen the windows, to fitting shutters, as are commonplace in hot countries. Of all the solutions I think that slatted shutters, perforated external blinds or brise soliels, are probably the best value. IR reflective film is expensive, and does impact on the light that gets though the windows all year around - the grey tint may well be a bit oppressive in winter.

You can get DIY install awnings, that aren't too expensive and have the advantage of being able to be rolled/folded up when not needed. Might be an idea to try them first. I've just ordered a pergola kit to screen our living room and my wife's room from the sun in the later afternoon/evening. That will (hopefully) have the added benefit of allowing us to use the patio on days like today, when it's been close to 30°C outside and too hot to sit outside in the sun for very long.

 

Don't leave curtains, windows or doors open on the sunny sides of the house in hot weather. First rule. Kids or no kids...

I have a south facing house and the front and side get steaming hot. Curtains are all shut. Windows closed. Just trickle vents open to keep small air flow.

Once sun has gone in and it's cooler out than in you open all the windows.

I always wonder whether a bathroom extractor fan in the main upstairs wouldn't be the lazy way of venting some heat too.

Also how well is the loft insulated? If that is stinking hot and the ceiling between it and the roof space isn't well insulated the heat comes in that way too.

I have also let trees and bushes grow around that sunny of the house to reduce the solar gain in summer a bit.

 

You need external shade: deciduous trees, sun awnings, external shutters. All or combinations. That is what Europeans in hot climates have been doing for hundreds of years.

 

Go outside if it's too hot inside.

 

Out of curiosity - What color is your wall after EWI?
My sister had insulation done with white render back in Poland. Not only it keeps interior much warmer in winter but also much cooler on hot sunny days in summer. The need of aircon pretty much evaporated even on days with temps > 30C.

Back in UK my house has white/cream wall render on one side (the wall is at ambient temp) while the other side of the house is just exposed bricks. They heat up like oven on sunny days so had to get aircon.

 

The walls are white/cream and are doing a great job - the issue is not heat from the walls, but heat through the windows/doors.

Love the idea of having some fruit trees, but these would have to be quite high to be effective, and our garden isn't very big.

The pagoda idea above is a great one and will be pretty easy to do, and will get some quotes for a Brise Soleil over the patio doors. Can anyone recommend a good supplier?

 

Fruit trees; at least you can restrict their height and form and pick the fruit. My beech tree stands at 25 m tall; too big and a maple is getting to 17 m again too big. But plums and apples can happily get to 5 m. and provide fruit by year 3/4. Pears are a problem, they get to ripen all of a sudden, cherries get nicked by birds.

 

...and deciduous trees have the advantage of giving less shade in the winter.

 

And get the leaves for compost. I should have added that there are varieties of plums and gages which extend the picking season, freeze well for plum pie and crumble. The gages are just different plum varieties, green gages, Cambridge gages (yellow) both very sweet and less acid than Victoria and the chances are you will end up with 100kg of fruit from 3 trees by year 5. What the hell do we do with all this? Put it on porridge in the winter! We also (should say my wife) grow berries up any bit of fence or wall. Boysenberries, Tay Berries thornless blackberries grow tall up to 3.5 m up wires and have masses of fruit. Had my first Boysenberry today, close to a blackberry but somehow sweeter distinctive taste, Tay Berry massive raspberry like fruit, but less acid. The berries all root from runners. The trick is labelling them because you can end up mistaking them until full in fruit so you might rip up a wandering plant you are keen to keep.

 

You might be imagining that your house suddenly has a problem after insulation and needs some solution. Most people would get used to living in an insulated house quite quickly.

 

Take a leaf out of the mediterranean designer's handbook. External shutters. Insulation for windows. Make them smart if you're lazy. Depending on your house orientation you might find there's a couple of specific places where this will make the most impact.

Keep the sun out during the day. Don't replace winter energy use with summer energy use, that makes no sense at all.

 

As already mentioned in post number six!

 

I was inclined to make a similar observation the other day, being very hot and hot inside my 'new' house.

"They say" that extra insulation stops heat getting in as well as out. Have to say, that's bollocks, if you hear that I have to conclude it's nonsense. It just traps heat, that is all.

 

I've yet to see a conductive insulation material that works like a thermal diode and only allows heat to travel through the material in one direction. Closest to that would be low e glass, arranged with the coated surface facing inwards, as is common in double and triple glazing. These low emissivity coating are good in winter, they reduce radiated heat losses through the glazing, but they are bad in hot weather, where solar irradiation can easily allow around 500 W to 1000 W per m² to enter the house through the glazing, with maybe only 10% to 20% of that being radiated back out through the glazing. Shading windows, or fitting reflective coatings or films on the outer surface, can very significantly reduce solar gain. Given that we seem to be seeing a net increase in temperature, perhaps we should start to copy what's been done for centuries in countries with warmer climates, and start to consider external shutters and blinds.

The main problem with homes that overheat is that they've either not been designed properly in the first place, or that they've had additional insulation added without taking a holistic view as to how that is going to impact comfort all year around, particularly how the house is going to respond to high levels of solar gain, mostly through the glazing, but also through low decrement delays walls and roofing. It doesn't help that the standard models used often define overheating as being greater than 25°C and accept that a 5% risk of exceeding this temperature is acceptable. In my view this is too lax, I believe the limiting temperature needs to be a couple of degrees lower and the percentage time each year this is exceeded needs to be around 2% at most. The problem being that whilst 25°C might be acceptable during the day, many people will find that to be far too hot at night.

The key things with thermal design for homes is ensuring that the decrement delay is longer than the mean period of solar heating, that there is an adequate ventilation strategy (something like night purging, for example) and that the solar gain from relatively poorly insulated elements, especially things like windows that can allow a lot of solar radiation through, are properly controlled.

Just getting the decrement delay out to at least 12 hours, ideally more than 18 hours, makes a staggering difference. Our ancestors probably had a better feel for decrement delay, perhaps unwittingly, when building homes with thick walls made from high specific heat capacity materials, and using thick roofing that similarly has a pretty high specific heat capacity. Modern homes often use very, very low specific heat capacity insulation, like PIR foam, that, combined with thin walls, ends up giving a decrement delay that is very short, perhaps only a couple of hours. This has a major impact on comfort in hot weather.

FWIW, our house is pretty well insulated, 300mm under the floor, 300mm in the walls and 400mm in the roof, with the wall and roof insulation being specifically chosen to give a long decrement delay (a bit over 20 hours). The net result is that heat being conducted through the walls and roof from outside doesn't have time to reach the internal surface and start warming the house during the day, so when it starts to cool in the evening the heat flow direction reverses, with the heat that's made it part way through the walls and roof starts to flow outwards, cooling the structure down ready for the following day. This results in a stable temperature inside the house, a bit like that in older masonry buildings with very thick walls. The stable temperature tends to be subjectively more comfortable, too, not sure why, but it also seems to make living with a slightly lower room temperature in winter acceptable.

 

In simple terms, you have to stop the sun shining through the windows and heating up the internal surfaces of the house.
External shutters, as mentioned by others above, is an obvious answer but may not be quickly/easily implemented.
So other simple fixes might include-
Solar reflective blinds
Erecting a big parasol outside patio doors on sunny days
Closing the curtains

 

Agreed.in the short term, closing drapes tightly ( hopefully these are heavy thermal types), with windows behind open, will stop heat penetrating into the interior. In the long term sun blinds or shutters are better.

 

I've tried this (with curtains) and can't honestly see the different, I pull the blackout curtains closed and open the window ajar so heat builds up in the window space and being focussed there can then vent as quickly as possible out of the window. Maybe it works ... slightly .... unconvinced it makes much of a difference.

In Australia we had the outside blinds and they worked extremely well.

 

Agree. The Aussie solution ( tight fitting almost vertical external blind) is extremely effective.

 

Key is to stop the heat getting in through the window, so shading the outside. The windows we have that are fitted with long wavelength IR reflective film on the outside barely get warm on the inside, whereas those without the film can easily top 30°C on the inside surface. Once inside, heat can't easily escape through the glazing, because of the low e internal coating on the inner panes that reflects most of it back inside (useful in winter, not useful in summer).

 

I agree with the others above who say external shading is better than internal, and would probably obviate the need for air con. I like the frequent comparisons to how Europeans and Aussies use shutters and awnings. Another comparison could be made with our past selves, for some reason we've all forgotten about awnings.

Trafalgar Square and Northumberland Ave c.1890

 

I fully subscribe to the "keep the heat out" faction. Personal experience was in Germany where we had a vertical blind a bit like a UK shop-front roller blind that could be operated by hand from inside the house. Really kept the heat out and as a bonus made the bedroom pitch dark even in the early morning summer light.

On a more prosaic note, and having just moved into a much-better insulated house than we had previously, I've rediscovered the fact that opening a window slightly on both the hot and cold sides of the house creates a nice through-draught that that takes the edge off the heat.

Lowering blinds and drawing curtains will help, but external solution is best for sustained high temperatures.

 

I tend to adopt the chimney principle in which I open a window either side of the house, along with the downstairs doors and French doors to allow air to get sucked up into that stream.

I would not venture to say which side of the house the window needs to be open more than the other, but usually it can be optimised by adjusting the aperture sizes either side. I think it might be more to do with wind direction (however slight) rather than temperature, but there is definitely a 'tendency of motion' one way to the other, which can be maximised by aperture opening.

PS I know I bang on about it but this summer is definitely cooler, on the subjective experience of it, than last year, slam dunk cooler. I get eczema and it is aggravated in heat so I have air conditioners to ease the burden, so I know full well when I need to add active cooling. I have not yet got them out of the garage, they remain unused this year when last year they were on most days in June, I think I had to get them out in May. Not needed AC yet this year.

 

Take a tip from the ancients building and living in the Middle East - Solar Chimney.

https://en.wikipedia.org/wiki/Solar_chimney

I use Velux windows above a staircase to create an air flow across the house to cool on hot days.

 

Struggling to find an installer in Yorkshire for external insulation. Are you willing to post who you used.
?


Sent from my iPad using Tapatalk

 

Indeed, and it varies on how hot the room already is and how hot the outside air is. I tend to close the curtains and open the window slightly, just enough to mix the air between curtain and window to outside. The idea is that solar heat is trapped by the curtains then ventilated out of the window, one might naively imagine this halves the solar radiation getting into the room.

 

I recall many years ago being impressed by the ingenuity of Victorian building designers. I was visiting Bowes Museum and the guide was describing the huge glass atrium dome. The top centre portion could be opened to allow hot air to escape and around the perimeter of the circular base there were dozens of candle holders. He explained that in hot weather they lit the candles and that created a large upward draught which drew the warm air from lower down in the building and for fresh air to then be drawn into the building from the cooler basement areas. Quite ingenious and counterintuitive.

 

Presumably they could have got the same effect by opening lots of ground floor windows and letting the stack effect do the work. Candles are expensive!!

Before the oil money led to Western style redevelopment, Middle Eastern buildings commonly incorporated "wind towers". These created an air flow which has a great cooling effect in spite of the high air temperature. I remember being very impressed by the market building in Sharjah in the 1970s. Impressive concrete shell roof with wind towers. No AC. I expect that they have demolished it by now

 

Meanwhile, back at the highly insulated house.........

I, personally would like to know much more about your house and what you have done to it, Jimbo. That's because I believe that is what a huge proportion of the housing stock needs doing to it to get us anywhere near the zero carbon targets everyone is talking about. Not to mention reducing fuel bills!

My immediate questions are:-
1 Thickness and material of all insulation?
2 Do you have a fresh air system with a heat exchanger?
3 Are you working towards the Enerphit standard ?(Pasivhaus for retrofit)
4 Obviously costs would be good to know, if you didn't mind.
5 How has it all affected your winter heating bills and general comfort?

This would be better in a new dedicated thread I think.

You'd be doing most of us a big favour since practical experience trumps any amount of theory. It might also attract others with similar projects to pitch in with their experience.

Good luck with you sun blinds, anyway!

 

I have posted bits and pieces about this elsewhere, but for the sake of convenience...

1 Thickness and material of all insulation? Combination of 90mm EPS and XPS over the original house; cavity + underfloor + roof insulation to current regs in the refurbished sections... and this is the part of the house where we have a real heat issue. Double-glazing to current regs throughout. Quad-glazed "pasivhaus grade" roof light (which gets very hot).

We have been blocking the rear doors with a blackout curtain, but this doesn't seem to be having much effect.

2 Do you have a fresh air system with a heat exchanger? No, learned about this too late in the project. I think the house would benefit.

3 Are you working towards the Enerphit standard ?(Pasivhaus for retrofit) No.

4 Obviously costs would be good to know, if you didn't mind. Not sure how useful this would be as every install is different, and mine was part of a bigger refurbishment project.

5 How has it all affected your winter heating bills and general comfort? General comfort is better as we have more control of the environment. Instant hot water is a bonus too (no more combi boiler).

Random data point for (all) consumption:

• Jan 2019 approx 2,600 kWh (dual fuel)
• Jan 2022 approx 1240 kWh (electricity only)

 

I fitted tilt-and-turn triple glazed windows with “perfect fit” blackout blinds on all south-facing windows. They work really well in summer. Blackout blind down all day window tilted in for airflow.

 

I use this sort of thing on office blocks all the time
As its installed, as you walk down the building you can actually feel the difference in temperature

Solar Film | Reflective Window Film | Heat Reflective Window Film

Heat reflective window solar film from Sureguard reduces heat and glare by up to 90% while letting in full daylight, also providing privacy and security.

www.sureguard.co.uk

 

I've had some quotes back...

Brise Soleil ... 2k (4.5m x 0.8m)
Awning (motorised) ... 3.7k (4.5 x 3m) -- this would be problematic due to the room being single storey
Air con (7kw) ... 2.5k
Curtains ... 1.2k
Green roof ... 2.2k

Love the brise soleil and found the "perfect" one, but, we are currently blocking the patio doors with a black-out curtain (on the outside) and this is not making much difference, so I am worried it wouldn't be enough on it's own.

It's looking like the AC is the only cost effective solution

 

Can't you just buy and install your own external canopy/awning/sunshade.

 

Has anyone had any experience using solar film on their windows? Wondering if that would be a happy compromise to not being (realistically) able to have external shutters?

It seems reflective blinds are a false economy as the heat is already through the window, but seems I could get a reasonably noticeable blocked effect using solar film applied directly to the glass, with the cost being less visible light coming through and so a darker, gloomier room.

 

It seems reflective blinds are a false economy as the heat is already through the window

Most of the power from the sun (heat) comes from the visible, and near IR, so you can just bounce it straight back out, as it is absorbed very little by the glass. My fancy double gazing passes the UV though the outer and absorbs on the inner, as well as reflecting long wave IR. Not all IR is created equal.

I am quite interested in Roger Seheult, MD of MedCram's ideas about near IR. Although he is a bit out on his own on this, he is no quack.

https://www.youtube.com/results?search_query=medcram+ir

It is not a good idea to rid yourself of near IR at all, if he is correct.