House Insulation

[Rezi]

I moved home earlier this year and my new house has very thick brick walls (500mm) but no insluation. The ceilings are also quite substantially built. Bricks here are the type with a lot of voids.
I had hoped, through the warm part of the year, that the thick walls would not require any insulation due to the thickness but I've noticed that as the temps have dropped the central heating has struggled to keep the house above 20C.
There are other mitigating factors relating to the central heating but I'd like to know whether thicker brick walls are any better or worse than standard brick construction at retaining warmth.
Also, has anyone tried using a thermal imaging/heat sensing app and are they any good?

Steve

 

[Mike G]

Steve, this is sort -of the same sort of issue that stone buildings face.

There are two basic strands or approaches to keeping a building warm with the minimum heat input. One involves masses of insulation, which holds the internal heat within the lightweight fabric of the building, and in the air. The other is exploiting thermal mass. This involves trapping large amounts of warmth (or " coolth") within the heavyweight fabric of a building, and topping up the losses with a heating system. Think of putting an empty baked bean tin in the oven, alongside a full one (don't try this at home, folks!). Obviously, if you remove them both at the same time, you'll be picking up the empty tin with your bare hands within a few minutes, but the full one will still be hot in half an hour.

Supper is served. I'll be back.

 

[Rezi]

Well, I clad my last house with 100mm of Nicocell (like polystyrene blocks) which worked a treat but that house has triple glazing and a lot of concrete in it which helped retain the warmth.
How do I trap the warmth/cool in my house other than with insulation? I have double glazing and the house is not drafty.

 

[Mike G]

Unfortunately, those extruded hollow bricks which are used all over the continent, are neither one thing nor the other. They are better insulators than our bricks, but are comparatively lightweight. Worse still, the general method of building with them involves casting concrete frames to take all the structural loads, and just using the bricks as infill. This means cold bridging through the concrete. Obviously I can't be sure of the structure of your house, and am just talking in general terms.

Personally, if there is no insulation in the walls, and if the eaves and gable overhangs of the roof are big enough, I'd consider insulating externally. There's quite a lot to think about (details around the doors and windows, a potentially ugly overhang at DPC level [ideally an additional skin of brick plinth would solve that], and, most importantly, what you clad the outside with and how you make the whole lot stay in place on the wall. There is also moisture flow through the wall to consider. However, if it can be made to work, you get the huge benefit of the thermal mass of the external walls all being within the insulated envelope of the building. It's this principle which I've used for 20+ years in producing some of the most energy efficient buildings in the country.

 

[Mike G]

Well, I clad my last house with 100mm of Nicocell (like polystyrene blocks) which worked a treat but that house has triple glazing and a lot of concrete in it which helped retain the warmth.
How do I trap the warmth/cool in my house other than with insulation? I have double glazing and the house is not drafty.

Sorry, our posts crossed. I offered my suggestion just as you asked the exact same question! I don't think there is any way other than insulation, but if you could insulate externally it could make a tremendous difference.

As for the triple glazing......Even the best glazing is one tenth as energy efficient as the walls it is fixed into, typically. If you can't justify the hassle and cost of replacing your windows, then consider insulated shutters. These could be internal or external, so long as they fit tight into the opening when closed, and would be a relatively straight forward DIY job for a man of your abilities. They would be tremendously more efficient than even quadruple glazing when they're shut.

 

[AJB Temple]

Skill Builder you tube has some interesting vids on external insulation. Quite quick to apply and very suitable for render finishes. Doesn't work for us.

What we are doing gradually over a few years, is treating each room as an insulation zone to trap heat. Newly built rooms are built heavily insulated, but for the rest of the house (a barn originally) we are doing key rooms that we want to be especially warm as follows, after repairing the cladding on the whole house and adding an additional 200mm of rockwool insulation (which we call fluff) in the attic (already insulated to a degree):

Seal all gaps around windows and oak frame with low expansion foam.
Add 200mm or 100mm (depends on oak frame) of foiled foam insulation on all external walls, with new studwork and use low expansion foam and alu foil tape on any gaps. Odd bits are stuffed with fluff.
On internal walls, I also add insulation, but part of the reason for this is I am panelling anyway and adding trunking and additional pipework.
Rewire as we go, adding lots of sockets, and replace all radiators. All rads have thermostatic valves and some have smart valves. Aesthetics are relevant.
All water pipework is the new type that comes insulated from manufacture.
Add panelling to hide the insulation. Mostly made out of either ply or MR MDF.
Where I need to lay new floors, I insulate them. Unfortunately the building design (pretty old and four or five changes of level on the ground floor) is not practical to have underfloor heating or air ducted heating - else I would.
We are moving to having multiple sources of heat. We do not have mains gas, but we use oil, electric, log and shortly we will have pellet.
Triple glazing where glazing is replaced.
Some rooms are designated cold and although insulated, we barley heat them (larder, laundry, unused bedrooms).

Next year we will look again at economics or replacing the boiler. This is an external plant.

Most of us cannot do this kind of thing all at once. So plan it over a few years.

 

[AJB Temple]

Mike posted prior. I am shocked at the info on triple glazed vs walls.

Insulated shutters is a really good idea.

This has triggered me into thinking not of shutters, but removable insulated panels for some windows. Our main concern is the living room as a winter "hot zone" . Most of our "windows" are actually double glazed doors. We can seal the room at night with just three lightweight panels (one south two north).

 

[Mike G]

......I am shocked at the info on triple glazed vs walls......

In really broad terms, a high performance window will have an overall U value around 1 (you can imagine the caveats wrapped around that broad statement), and a decent wall will have a U value around 0.1. Obviously, there is a far greater area of wall to window in most houses, so much of the heat loss is typically through walls rather than through windows, but yep.......10 to 1 is a useful rough guide to their comparative heat loss per unit area.

 

[Rezi]

We did all the upgrades using the best quality materials we could find on our previous house but that was a more modern construction with concrete floors and brick walls. We put in triple glazing with insulated shutters, 100mm external insulation rendered and painted, 200mm rockwool in the loft, electric underfloor heating and solar panels.

This house is a bit older and more robustly built but was recently renovated by the previous owners (also brits). They weren't even in the country when the builders were doing the renovations and they were ripped off. The heating pipework system is stupidly complicated and someone thought it would be a good idea to locate the boiler at one end of the house 35m away from the farthest radiator with 10 others in between including hot water underfloor heating in a 40m2 kitchen. Fixing it would entail ripping up all the recently tiled floors which is not a path I can tread either financially or emotionally. I've already had the unexpected expense of having to get the roof re-tiled which was my new workshop fund :x

There's enough overhang under the eaves for insulation but there is almost no overhang on the sides under the guttering. I'll have a good look around the outside tomorrow and try and identify any problem areas. The windows are also fairly new and are standard upvc double glazing.

 

[AJB Temple]

Ah. We have got the T shirt with a longish house (35 metres approx) and a boiler (outside) at one end. It takes about a hundred years for hot water to get from one end to the other. So we have had to be creative.

I did at one point consider stripping all the cladding off and insulating the outside. However, even with the existing cladding and fixings stripped off, Mike quickly made me realise this was a daft idea as we do not have anything like enough roof overhang. From the calcs it seemed to me that 200mm of insulation was what made the project worthwhile (plus whatever is used as a weather layer).

The only other option in an old building therefore is insulate the inside. At least the core that is used most. Clearly this means some internal volume is lost. But really only on the outside walls, or at least the coldest and most exposed walls. We have decided that is worth it, and is part of our plan. This changes the the character of the property, but we decided to embrace change and have some parts very modern.

Mike's education (of me as usual) is interesting on glazing. Obviously I know a few sheets of glass is less than ideal, but a 10:1 difference is quite a lot As a lifelong curtain hater, and never having had a house in the UK with proper shutters, I shall have to have a rethink. In the kitchen we have sliding glass doors that are 6 metres. Triple glazed solar glass and south facing, but even so.....I can't do more with them. Winter is brief.........Good luck with your project. Let's see some photos of what you are dealing with.

 

[Rezi]

Here is a recent picture after the roof tiles and solar panels were fitted last week. You can see that there is very little depth under the guttering.

 

[Mike G]

It's a pity there isn't a bigger eaves overhang, but it shouldn't be a huge job to extend the roof. It's useful that the verge overhang is so large, because that is usually a bit more of a job to deal with. If you remove the gutter and the first couple of rows of tiles and battens around the bottom edge of the roof, you should be able to plant a short piece on the side of each rafter, extending the roof downward by one tile. This will cover the insulation, void, and render quite comfortably. It's a summer job, obviously, and you'd only need a low scaffold or staging to get safe access. I suggest doing the roof before the wall insulation.

 

[AJB Temple]

Interestingly you have a porch overhang at one end. I am wondering if you could continue that detail around (but tiled). That would permit the addition of significant external insulation and would not be difficult to build and would provide a potential useful but sheltered outside seating and BBQ area perhaps.

 

[AndyP]

I thought you might be interested in this which I have copied and pasted from elsewhere.

Back in 2007 Gary, aka Taffy Turner, did some heat loss calculations for me based on my existing external shutters. Gary is sadly no longer with us but I do remember him telling me that this sort of thing was his day job.

[*]

Frame material........ Hardwood
Glass Spec...... double, I've no idea if they are argon fill. They were put in when the house was built 15 years ago. There are none of those glass bubbles inside.
Inter-pane gap.... How do I measure? I would guess about 15mm
Shutter material.........softwood, 20mm thick
Glass to shutter distance.........300mm


Andy,

I have some results for you now, and they make interesting reading (from my point of view also). Using the information that you gave me, together with a few assumptions regarding frame hight and thickness etc (which as we are interested in the difference, won't cause too much of an inaccuracy) I got the following results: -

With shutters in the open position Uwindow = 2.4 W/m2K

With shutters closed Uwindow = 1.5 W/m2K

If you were able to make the shutters a better fit, so that the gap all around was <= 2mm, then Uwindow = 1.2 W/m2K

The U value is a heat loss in Watts per square meter of window per Kelvin (degree C - it's the same thing).

Assuming your house has a window area of 12 square meters (measure the area of the reveal, not just the glass), and an internal temp of 20 deg C and an outside temp of 0 deg C (reasonable for your part of the world during the winter), we get the following heat loss figures: -

No shutters - Heat Loss = 2.4 x 12 x 20 = 576 W

Loose fitting shutters - Heat Loss = 1.5 x 12 x 20 = 360 W

Tight fitting shutters - Heat Loss = 1.2 x 12 x 20 = 288 W

There is also a significant effect on the sight-line temperature. This is where the glass meets the frame, and is always the coldest spot on a window assembly - hence the point were condensation starts to form.

No shutters - SLT = 8.2 deg C

Loose Shutters - SLT = 12.5 deg C

Airtight shutters - SLT = 13.7 deg C

All of which tells me that it is worth closing the shutters at night during the winter! I suppose this is hardly surprising - as if the shutters didn't make much difference, why do most houses in mainland Europe have them fitted?

As an aside - this is the reason that windows in the UK open outwards, and windows in Continental Europe open inwards - it is to allow teh shutters to be closed from inside the room. As the UK traditionally doesn't have shutters, hence the windows open outwards.

Hope that this helps.

Regards

Gary

 

[Mike G]

That is interesting, Andy.

If I am reading that correctly, uninsulated (but tightly sealed) softwood shutters 20mm thick halve the amount of heat lost from a window at night. Right, so imagine what the saving would be for insulated shutters.

The first attempts at zero-energy houses in the UK all featured insulated shutters, for very good and obvious reasons.

As for windows-opening-outward/ inward thing......Britain does have a tradition of shutters, but they were generally internal. Georgian houses, for instance, featured folding panelled shutters which folded back into the splayed reveals internally. We also have a tradition of windows which open up & down or sideways (sash windows), with casement windows coming along afterwards. Sash windows could work with either internal or external shutters.

 

[AJB Temple]

What I have seen quite a bit in Hungary (worked there for a year) is the metal rolling shutters that are near ubiquitous in Germany. The modern versions of these are insulated. They run in a framed track, so there are no gaps. My inlaws and wife's place there have them. Must be available for retro fit. Also improves security.

 

[Rezi]

... it shouldn't be a huge job to extend the roof...

There are some issues with extending the rafters. Sitting on top of the walls are huge wooden ring beams (prob not correct term) with the supporting timbers jointed into it. Add to that that the tops of the walls step out gradually on the top three courses. It might be doable, I'll have to have closer look under the tiles.

Interestingly you have a porch overhang at one end. I am wondering if you could continue that detail around (but tiled). That would permit the addition of significant external insulation and would not be difficult to build and would provide a potential useful but sheltered outside seating and BBQ area perhaps.

Actually, the next part of the project is to demolish the porch/terrace bit and rebuild it but twice the size.

All of the windows except the two very small ones in the near part of the building have roller window shutters. They aren't insulated but I have been thinking about replacing them anyway as they weren't installed very well and are already looking a bit tatty.

 

[Mike G]

Bear in mind, Steve, that the roof doesn't have to maintain the same pitch. If it kicks up a few degrees at the bottom that not only works perfectly well and looks great, but it is very traditional (in many different traditions). As for the corbelling brickwork at the top of the walls.....I can't really see the detail but might that not be dealt with just by cutting out the back of the insulation?

Are your ceilings vaulted?

 

[Rezi]

I think I like the sound of the pitch kicking up a bit. I'll take a closer pic of the corbelling and put it on here tomorrow.

The ceilings are high (about 2750mm) but not vaulted. They are constructed with Acacia batons (approx 70x50mm with 200mm spacing) with a mix of modern and old plaster ceilings. Above the batons the loft is completely tiled with 30mm thick, 200mm2 stone tiles and a screed of concrete about 15mm on top of that. The two biggest rooms have beams.