We are very happy with our boiler, we haven’t really had any problems with it. We bought it through Oxfordshire Woodheat who service and repair it when necessary – I would happily recommend them.
I do know that pellet boilers have evolved significantly since we got ours 6 years ago and now are much easier to clean out and repair.
We love our heat recovery system – though it is tricky to find anyone who will service it in this part of the country so we tend to do it ourselves.
In order to improve the insulation in our house we built a second timber-framed skin inside the house, which has helped to make it much more airtight.
You can feel it cool at your feet, as the vent is under the settee with the insulated ducting routed under the floors. I don’t think I would call it a draught though. You can choose different speeds, if you felt it draughty. It’s usually pretty cool regardless of the outside temperature.
It would have been too invasive to rip up floor boards and deadening ash between the floors in all the bedrooms to lay ducting to vents in the downstairs ceilings. So the fresh air into the living rooms had to be taken from the MVHR unit in the loft, down a box section which I built, right down and under the floor boards downstairs, where insulated ducting takes it to vents which are screwed to the underside of the floor boards. These have open and shut sliding grills screwed down from the top of the floor boards, to allow us to control the air flow into the rooms.
No, we run it mainly in the during bathroom use and some evenings, if washing is drying etc. When we are out during the day the heating is off so we leave the MVHR off. If we left it on then the net effect of leaving it on, would be to gradually cool the house.
It doesn’t feel stuffy when the MVHR is off. I think the big difference here, is that my house is an old one, with lots of compromises for practical reasons during the refurb. If it was a new build, with maximum air-tightness, I think there would be a big difference in our experience of living in it.
We simply looked for the best insulation values we could get without needing to have too much thickness, which would encroach on the room space, as none of our rooms are particularly large. Just now, PIR is the best option. It is also relatively easy to work with and seal all the gaps between the wooden frame and the insulation.
We essentially built an internal wooden frame/wall, filled with insulation panels, which sits between 25mm and 30mm away from the stone wall, to still allow the wall to breathe. 50mm would have been better, but it starts to eat into the room size again.
Our air source heat pump does use more electricity when temperatures go below freezing to about -5 degrees. It uses power directly from the mains, rather than through the usual heat exchanger. You can image that it is difficult to extract much heat from freezing air. However, I do not feel it has ever been a problem.
We heat our water to a maximum of 60C but use a solar thermal system, which the heat pump will automatically top up in the late evening if needed. You need to get the water temperature to 60C to stop diseases in the tank. Basically, our gas boiler was completely replaced by our heat pump and we still use our original water filled radiators. We have recently had a ‘smart thermostat’ fitted, which will automatically turn down our heating when we both leave the house and takes the outside temperature into account.
Insulation in the loft and cavity walls is very important. Of course, a heat pump will only really provide a background heat, so if you like high temperatures of, say, 25 degrees then you may be disappointed. If you decide on an air source heat pump make sure you get an installer who knows what they are doing. I think there may be some recommended on the Superhomes site. The heat pump controls can also be a little difficult to understand, so make sure you, and your installer, know how to use them.
We have had our heat pump for nearly ten years and it has, so far, been cheaper to service than our old gas boiler. It is difficult to directly compare running costs as we both worked when we had our boiler but are now retired.
Yes. The passive ventilation with heat recovery is working fine. I feel the house is fresher and drier already, with no condensation on the window, despite my drying off clothes indoors. I will never have to open a window again and it should ventilate and cool in summer. Ventive have one various awards.
The house is designed to hold the heat and to keep an even temperature. Solid heavy floors (as well as walls) are an important part of this. They warm up when the sun shines, and store that heat to release it again at night. In the winter if the temperature outside dips, it stays warm inside; and in the sumner it stays cool. The heavy floors prevent excessive temperature swings by holding and releasing heat slowly.
It’s important first to explain that our earth floors have insulation underneath them. The ground floor build up is 250mm of insulation, a damp-proof membrane, 100mm floor slab, and then 75mm of rammed earth.
The earth is red clay sub-soil (not the black sub-soil) which was dug to make the foundations of the new house. We had to import some extra red earth to supplement it. We sieved to 10mm to remove larger stones. The earth is mixed to a workable consistency with a little water – as little as possible to keep the mix fairly dry – and then laid like a cement screed with a trowel finish. As the earth dries out, it shrinks slightly. This leaves the small cracks and fissures which run across the floor and give it character and texture. If the mix is laid too wet, too much shrinkage and too many cracks will result. If it’s too dry, it won’t be possible to work it to a smooth finish with a trowel. It may need a bit of experimentation to achieve this.
During the drying period – several weeks, but probably extending to 6+ months until it’s fully dry – we used a whacker-plate compacter to “ram” the earth to make it as dense as possible. During drying, we protected the floors with hardboard.
After it had dried, we primed the floor with citrus and linseed oil, and finished with a natural beeswax-based floor polish. This ensures it’s reasonably waterproof and sealed. When it’s fully dried, the floor is almost as strong as some sandstones – which after all are just sedimentary rocks firmed by compaction in the same way. We’re quite careful with table legs etc to avoid heavy point loads on the floor, which it wouldn’t appreciate.
The good news is that engrained dirt simply becomes part of the floor! In heavily used areas, the floor polish needs renewing more often, but generally just vacuuming or sweeping is enough. If there’s a real problem – someone put a stiletto heel through a soft spot in our floor before it had fully hardened! – you can simply break out a small area and remake it again.
The eight-year payback or whole life cost analysis that I was quoting is from the book by Professor Lubo Jankovic, Designing Zero Carbon Buildings Using Dynamic Simulation Methods.
The study looks at the “extra” cost of the energy efficiency measures in the old 1840 part of the zero carbon house including insulation, triple-glazed windows, solar panels etc. It then shows a method of accounting which recognises these construction costs and financing, and also that there are no fuel bills in the house, and also that cash is generated from the PV solar panels. This is the general principle of where the quoted 8-year payback comes from.
We used a firm called AMB Glass who were ok. They are in the Malvern direction, but I think any reasonable glazier could do it, not too complex. I have heard First Glass Birmingham are ok although I don’t have personal experience of them.
AMB supplied and installed our frameless triple-glazed units (ie. these normally go into window frames).
We sealed them straight into the building, which was less expensive and makes excellent airtightness. Elsewhere we gave opening windows which are slightly different.
Our builder then sealed the frameless units to the building airtight membrane with special tapes.
The specification of our units is 6-16-4-16-6, ie. two 16mm cavities which are argon filled, also two Low E coatings and warm-edge spacer bars to the cavities. All these measures greatly reduce heat loss.
Period details: Picture rails, window architrave and skirting were removed carefully and put back afterwards, battens having been positioned with this in mind. Period coving has to be replaced; a shop selling imitation antique coving put us in touch with a man who came and made a template of our coving, then came back a week later and EXPERTLY glued up a set of 1m lengths of new made to match coving smoothing all joints until invisible. Not cheap but worth it.
Yes. Where I expected fittings such as radiators, curtain rails and, especially, high level kitchen units, I made the battens wider. This gives you a bit of leeway in the fixing position and you are less likely to split a batten. In order to run services I omitted parts of the 2nd insulation layer, between the battens. Battens can run vertical or horizontal (or a mix).
25mm battens are ample as there are rigid foam boards behind them; 19 mm would be quite strong enough but I put extra insulation between battens and 25mm is usually the thinnest insulation available. I can omit this extra insulation where I need to run services. I use 4 fixings per 2.8m length, or more if hanging kitchen cupboards, radiators etc. there, when I also use a wider (not thicker) batten to allow a margin for error in positioning the cupboards etc.
Yes, with long screws into rawlplugs through the batten, the Celotex and into the external wall. This penetrates the VCL, but the batten covers the hole, and the screw head is snug in the hole. To be extra sure about the VCL you could mastic the screw head into the hole, OR cover it with aluminium tape.
And yes each screw is a small cold bridge; I guess it could be improved a bit by using the plastic hammer-in plugs which are often used in external wall insulation.
I guess if you wanted to really go to town you could put 25mm of Celotex over the battens, secured initially with a few dabs of mastic; then when you put the plasterboard on, its screws would go through the 25mm into the battens but not into the main insulation. That way neither the main screws with rawlplugs nor the plasterboard screws penetrate the full insulation thickness.
I used 25mm battens then thickish insulation behind. My standard spec, using Kingspan or Celotex, is 50mm wall-side layer then battens, with 25mm insulation between them, giving a U value in the region of 0.2. Using polystyrene or eco materials you would need 100mm then 25mm to get the same result.
Where it is necessary to restrict thickness of insulation (e.g. in window reveals) , a little insulation (especially if it is Kingspan etc) is a lot better than none, so you could put battens straight onto wall with 25mm proper insulation only between them, or maybe 19mm battens with 6mm insulation behind (if you can source it) and 25mm insulation between. Insulating behind the battens also protects them from cold and hence from condensation, and from any penetrating damp. The reveals which I have insulated are quite small so I just glued insulated plasterboard, with 20 or 25mm insulation, into them.
I think the insulated stud way will become the standard where people use soft insulation between the battens. John Doggart (another Superhomer) has used it in his SuperHome, and was able to buy studs with the insulation already attached, though probably cheaper to DIY it.
You have identified a drawback of the ready insulated plasterboard, as that plaster will not stick to aluminium tape, so on the one occasion when I used the ready insulated plasterboard, I relied on the skim plaster and crossed my fingers. I foamed between the floor and the bottom edge, which is covered by the skirting and the bottom inch not plastered, and then plastered the joints at the top and sides and relied on the skim plaster to give a hopefully adequate seal including joints between plasterboard sheets. Clearly not such a good seal as “my” warm batten system.
Another SuperHomer used ready insulated plasterboard, but noted that the boards came with the plasterboard slightly overhanging the insulation, giving a cold bridge where it was impossible to butt the insulation tightly together. So he carefully cut the plasterboard back enough to reverse the overhang so he could butt the insulation together properly, and then he filled the gap between plasterboards before skimming. Depending on the filler used this could also give a reasonable vapour barrier.
However having used both systems, I find that the warm batten system takes no more labour, gives a better result, and saves money on materials. At first sight you would expect the insulated plasterboard system to be quicker, but it is difficult to line up the boards accurately, and my builder who has done both systems for me agreed, to his surprise, that the insulated plasterboard system was no quicker.
One advantage of my system is that the whole insulation system is anchored into the brick wall, avoiding possible problems with poor adhesion to the insulated plasterboard and poor adhesion of old plaster to the wall (so I don’t bother to hack off old plaster).
The sheet(s) on the first wall you do go right up to the next wall. Then when you start on the next wall butt the sheet end against the face of the sheet on the first wall, but leave a 15mm gap to get the foam gun nozzle in to seal the joint.
I use just the standard no–nonsense foam, though I use a proper foam gun – £17.99 well spent. It takes foam cartridges with a different head, but otherwise the same and much the same price. But you will halve foam waste and halve the labour to apply it.
Between insulation boards I have used foam into a 15mm gap, filled to full depth, but now I just butt the boards and apply aluminium tape.
Against walls, floor and ceiling I fill the gap to the full depth to maximise both vapour barrier (the foam is not 100% vapour resistant) and insulation. The main vapour barrier is the room side surface of the insulation, which has aluminium foil covering, plus the sealing of gaps.
Where you have a window reveal there is usually only space for a very thin layer of insulation, but fit what you can to avoid condensation on the cold bridge which will otherwise result. I use the dreaded insulated plasterboard, and for such small pieces I just rely on plasterboard adhesive to attach them. To get complete plasterboard cover over the insulation, the plasterboard on one face (the reveal or the wall) needs to project beyond the insulation by the thickness of the insulation on the other face, so you need to cut away the insulation from the projecting part of the insulated plasterboard used on the reveal (or stop the wall insulation 20mm short if using 20mm insulation in the reveal).
In the reveal you could instead use 25 or 20mm of insulation and separate plasterboard, relying on adhesive for each layer (for glue adhesion, first sand both sides of the foil which covers the insulation). You can put rawlplugs into the reveal through the plasterboard and insulation, but if you have dud holes where you hit mortar you can end up with a Swiss cheese effect. When using battens any Swiss cheese effect is in the battens where it can be sealed with aluminium tape and then hidden by the plasterboard.
If there is no insulation on the reveals you will get condensation there, so line with the plastic sold for fascia as mould will not grow on it. It can be glued in place and the lip wraps round onto the main plasterboard for an inch or so, or you could cut off the lip and butt it onto the plasterboard on the wall. You could also use it instead of plasterboard even with insulation.
If you keep the old Victorian outer frames there is no reveal because the frames, behind the architrave, are flush with the plaster on the wall. In this case use wood or MDF to build the inner inch or so of the frame out to the thickness of the wall insulation plus plasterboard, then butt the insulation and plasterboard up to it. Seal the butt joint with foam and it will be hidden when you put the architrave back.
Yes. Two ways to do this:
1. On Victorian windows remove sill and any architrave (it is usually just nailed to the window outer frame, and can be prised off with care), fit a filler piece of wood, then reattach original sill and architrave. Or you could make up a single piece, but perhaps harder to replicate the original detailing.
2. Or, especially for deeper sills, extend the insulation and plasterboard up till flush with the surface of the window sill, then cover the old sill and insulation and plasterboard with fascia plastic.
Unless I were to have space to use my proper system, I use the insulated plasterboard with a mere 25mm of insulation just glued to the reveal; seems to work well for such small areas. If no space to use expanding foam just seal with mastic. 25mm of insulation sounds pathetic, but it is enough to stop condensation, so worth doing.
The plasterboard has negligible insulation value compared to the actual insulation, so there shouldn’t be any condensation on the warm side of the actual insulation, and vapour which gets through it stays as vapour so can come out by the same route as it came in. Official advice for when using more than one layer of insulation is to put the thicker layer against the wall, then the thinner layer, so that any vapour which gets through (gaps in) the vapour barrier meets the join between the two layers at less than half the temperature drop.
Any good vapour barrier, such as DPM plastic sheet, will do fine, as long there are no gaps, which means securing the edges to walls floor and ceiling, usually with 25mm square battens, and overlapping joints between sheets with a fold and tape.
In addition you need to consider possible water damage to the unprotected Kingspan on its cold side from any water coming in through the brickwork, so, at least on the South and West walls, either protect with a breather membrane or create a small air gap. One way of making an air gap is to put non rotting battens, say 20-25mm thick, behind the insulation. These could be plastic or extruded polystyrene (which unlike expanded polystyrene and Kingspan is fully water resistant). Put them directly behind where the wooden battens will go, mark the position on wall/floor/ceiling, and give minimal securings; then the screws for the wooden battens will hold the plastic ones in place, and there will be no risk of bowing the insulation with the wooden battens.
SDS drills are great, easy quick and effective. They go through hard brick including “black hearted” bricks at 5 times the speed of old fashioned masonry drills, and their chucks last MUCH longer. The drill bits are expensive but, because of the superior action of the drill, the bits last MUCH longer, so cheaper in the long run. I have a “pneumatic” one, a German make. I also made the mistake of buying a cheap and powerful Chinese one, not pneumatic, it is so powerful and violent that it cracks the brick instead of making a hole!
I didn’t consider it, as wood is easier to use, and being on the warm side no risk of rot. On the other hand if you need to screw into the studs later, when you have forgotten where they are, it would be much easier to locate metal studding using a magnet. My preference would be to make the wood magnet-responsive to be easy to locate; you MIGHT be able to do this by painting it with a paint containing iron, google iron oxide paint.
An advantage of wood is that it pretty much seals the screw holes in the insulation, which steel studs would not do as they are hollow and full of holes.
On one wall there was a possible damp problem, so I used a different system with a framework on the cold side (also often necessary if a wall is very uneven), and there I used metal studding to avoid risk of rot; It was more difficult than wood cos of my being new to the system, but with experience it would be quite easy. Then I put the insulation against the frame (NOT between the steel studs as that leaves a cold bridge and probably gaps where insulation meets steel stud) , sealed it, and screwed plasterboard through the insulation into the frame [slight damage to vapour barrier] having marked the stud positions on the floor and ceiling.
To combat vapour leakage, nothing except that the wood battens seal the hole fairly well. You could put a bit of Aluminium tape over the screw heads I guess. Re: cold bridge, I lived with it; if someone makes strong enough plastic screws that would help, but they would have to be strong enough to bite into the plastic rawlplugs. With steel studding I guess only steel screws will bite into it.
One thing I have learnt is that with my system the plasterboard stays in position with no cracks appearing, while with the insulated plasterboard and adhesive system you usually get slight movement causing fine cracks at joints between boards (as well as an uncertain vapour barrier).
When we had 3 quotes from plasterers to insulate a room two years ago, two of the plasterers preferred to use insulated plasterboard on battens, at no extra cost, to avoid cracking. They were going to put the battens against the wall (on the cold side) but were happy to use instead my system with separate insulation and plasterboard and warm battens between them, which was what we did. They wanted to leave a gap at the bottom, which all plasterers do it seems, to avoid the risk of the plasterboard getting wet, but agreed that the insulation could be right to the floor as it is less sensitive to wet. So I asked the one who we appointed to leave a 15mm gap at the bottom of the insulation (which he did though it was only about 8mm in places) and then I sealed it with expanding foam. And the same around the other edges.
For ducting we use ordinary 68mm drainpipe, but you would have more heat and might need something wider, maybe 100mm soil pipe. Or you could use metal chimney liner (mix of flexible and rigid perhaps) or proper air handling ducts (often square). When our collector gets very hot it gets a nasty plastic smell, while the proper air ducts are usually metal I think. In your stove heat system the duct would not get so hot, unless it was very close to the stove, so plastic is probably OK, though metal would be better.
We have 2 pipes, return to the solar collector and flow from it to the room. We pump the flow air with a nice big in-line centrifugal fan on a lowish setting; using a big fan on a low setting is quiet and energy efficient, ours uses 18 watts on speed 2, 11 watts on speed 1. The fan is at the end of the flow pipe so it is sucking, more efficient than pushing. The return pipe is passive. The fan is a Nuaire flatmaster anti-condensation unit which I had kicking around, see here; you want item 9, last on page, £246.24. Or you could use something cheaper but this one has a filter and is quiet and energy efficient.
Our original plan was to run the ducts under the wooden suspended floors, hanging into the crawl space from the joists. However so far the air just comes from and to the south facing Living room (and up and down to the solar collector via ducts attached to the outside of the wall and insulated), so no horizontal air movement needed.
My system is controlled by a cooling thermostat, aka a reverse acting thermostat, which is set to its highest setting of 30 degrees C, so when the air in the collector reaches 30 the fan switches on.
I just cut off the surplus with a sharp knife. It still looks messy but will be hidden by skirting board.
Foaming vertical joints is same, mess is hidden behind plasterboard .
Foaming overhead joints is “interesting!” as gravity is against you. One way is to stuff bits of solid foam into the gap, then just fill remaining gaps with plaster or filler or decorators caulk in a gun. Alternatively I had fair success covering joint with wide clear tape, then cutting slits big enough for nozzle every 18inches or so and foaming into the gap – the clear tape lets you see the progress of the foam. Next day remove tape and trim away bulges. Remaining mess is covered by plasterboard and/or plaster. You could use this on vertical joints too, to reduce mess a bit.
Spend £10 or so in Screwfix for a metal foam gun. Reusable any number of times, you buy foam cartridges with a different top. Saves time as much easier to use, and money as you can leave a part-used can on it for weeks. Just scrape dried foam off tip before next use. You have to leave a can on it, OR if it will not be used for a month or more buy the gun cleaner can and clean it out.
Yes I did. This is commonly used where the wall is very uneven or incurably damp. My system is quicker to install and takes up less space and the only wood is the battens which are warm and dry being on the warm side of the insulation, so I used it on most of my walls which are true-ish, being a Victorian house. However I did use the frame system in some rooms, ventilating the space behind to avoid rot in the frame. You only need a small amount of ventilation, and it should resist the entry of rodents and insects.
On a cottage with uneven walls, or if you want to go straight across a wall with an unused fireplace, you would use the frame system, with a DPC (a piece of builders plastic) and some insulation between the sole plate and a solid floor.
The (ventilated) air gap behind the frame is cold, so should be insulated and air sealed from rooms beside or above or below if they are not insulated the same way with the frames aligned.
Screws are a weak point in either system. To limit vapour transmission around the screws I put a bit of self adhesive aluminium tape over the heads of the long screws going through the battens and insulation and into the wall. For heat conduction perhaps I could have used plastic screws? Screwing the plasterboard to the battens is not a problem as the battens are within the heated envelope, whereas with a frame the frame is usually cold. In theory you could put the insulation behind it but it would be very fiddly, since the reason for using a full frame is to have an air gap behind it.
In the solid floored kitchen we were able to cut the floor tiles at the edge and dig a narrow trench down as far as I could reach, about 60 cm, and insulate it, joining the insulation to the main wall insulation with expanding foam (easier than trying to carry a single sheet down into the trench). This was to limit heat loss through the floor, as most of any floor heat loss is at the edges. This avoided ripping up nice Victorian tiles and was much easier as we were lucky in that under the tiles we just had to dig out an ash base, not battle with brick rubble. It would be hard to do this with a frame system as we removed the bit of floor which the frame would stand on.
This is my opinion as we did no testing. As we did improve the energy efficiency of the whole home down to 0.15 or below the heat load for the home was really low therefore it worked well. However, as it is not delivering heat convectively but only conductively its ability to get heat out is compromised as you add furniture into the room. Also if you fit them get a chippie to do and not a plumber as otherwise it will be a dogs breakfast!
I used the Knauf Ecose internal wall insulation system on the inside of the external walls. This comprises:
90mm recycled glass mineral wall ecobatts between extruded polystyrene Ecostud work (to avoid thermal bridging) directly on walls. 600mm gaps between stud centres. Then a 12.5 vapour check plasterboard applied to the surface. No air gap.
I used 27mm foam backed plasterboard on the return wall to avoid thermal bridging at corners.
My house is still being monitored to see how it performs, funded by Knauf insulation.
.Warmer home – increased thermal comfort
·Lower carbon emissions
·Lower gas bills
·Loss of thermal mass
· Loss of breathability if you have a breathing wall unless you use a breathing wall system such as wood fibre and lime plaster
· Smaller room size
·Increased risk of thermal bridging unless the insulation is continuous.
·Loss of internal features unless they are replaced e.g. cornicing.
·Disruption to occupants during works.
I recommend you read the English Heritage guide ‘insulating solid walls’. In preference I would always externally insulate a heritage property if it is possible.
*So increased risk of interstitial condensation – Interstitial condensation can lead to damp walls and fabric decay and increased internal condensation and mould build up which can give rise to health problems for occupants. Insulation materials with low permeability are not entirely incompatible with older construction but careful thought needs to be given to reducing levels of water vapour moving through such construction either by means of ventilated cavities or through vapour control layers.
**I recommended insulation returns into window reveals using a shallower depth of insulation to reduce thermal bridging. You also need to run the insulation down to floor joists. You can also use airtightness tape around edges to reduce thermal bridging at edges.
***Rooms will have to be cleared, cornices and skirting’s and architraves removed and replaced probable with new. Sockets will have to be re fitted to new wall depth, window sills and window reveals extended out to take new wall depth.
We considered draught proofing and replacing just the panes with thin double glazing, but in the end went for full replacement of them with period style windows made by our contractor. They did a very good job.
Of all the things we did, this was the least cost-effective from an energy saving perspective. We estimated a 40 year payback time from fuel bill savings… However, it is the most easily understandable for buyers, so is likely to increase the value of the house, and also reduce noise a bit.
As it was, the wood of the original windows was suffering a bit, so full replacement had other benefits. But if this wasnt the case, then I think really well draught proofing it would have been the best from a cost-benefit perspective.
Unfortunately, our contractor no longer exists as a business, even though they did a very good job for us.
The cavity was filled using a high-performance polystyrene bead (EPS) prior to the application of external wall insulation. We did this for a number of reasons:
1. To help insulation value overall – i.e. original, uninsulated cavity had a U-value of appr. 1.4 (W/sq.m K). Cavity insulation (CWI) reduced this to appr 0.4.
2.To reduce thermal by pass potential for external wall insulation (EWI) layer. This is 100% essential. Without CWI, warm air escaping from the house would effectively use the empty cavity as a chimney (hot air rises) and out to atmosphere. So without CWI, the EWI would be useless. CWI+EWI give an overall U-value of appr 0.12.
We have some areas where EWI was not possible (<10% of available wall area of house). In these areas, we still have CWI, but switched to internal wall insulation (IWI). These walls have a U-value of appr. 0.17, but beware there is a higher risk of interstitial condensation, so either select a system with good vapour control layer (and that this is put in very well and sealed), or is diffuse open, such as wood fibre with lime plaster.
To read more, go to the home page and type in a topic into the search bar – I have tried to tag each entry so that everything is searchable. I also need to post more updates on recent performance when I get time!
We used polystyrene bead (EPS – extruded polystyrene), as opposed to mineral fibre, for two reasons:
a) EPS flows exceptionally well compared to fibre – we needed to ensure no/little air movement in the cavity.
b) Should there be a risk of interstitial condensation during certain times of the year (the moisture models showed this as a very small risk in October) then EPS will not get damaged, or absorb moisture and transfer this into the wall (damp problem). Mineral wool can absorb moisture and ultimately degrade.
Our sun room is not a conservatory in the normal ‘buy a package’ sense of the word. It is orientated north-south. It has a mass concrete heat retaining floor and continuous 3/4 depth windows on south & part east side that are triple glazed. The north and (part) east wall is built to modern building regulations using cavity insulated brick + blocks. The sun room has a deep insulated peaked roof with three double glazed velux windows on the south roof slope.
The cavity wall insulation in our house was carried out in two phases….
The first was commissioned by the previous owner of the 3 bed semi we bought over 14 years ago – I believe the insulation was put in a number of years previous to that…..
This insulation was polystyrene beads which at the time was probably one of the most effective ways of doing cavity wall insulation… It still works fine, although I would guess over the years it has settled quite a bit …… no problems with damp ingress and the original walls have little heat loss.. I still get a few beads roll out when I drill a hole in the wall for shelving etc!!!
We extended our home in 2000 to a 5 bed semi and as the new walls were built the local builder who carried out the work utilised mineral wool batts in the cavity, taking care to keep clear of the damp course …. this still works fine and again, no problems of damp course bridging or of damp ingress…..
I fitted the Nuaire system myself with a mate and used the Polypipe (Domus) radial duct system with it. To my knowledge its the first time a Nuaire system has been installed with the radial system, and it seems to work well. I used the radial system as it makes the retro fit far easier, especially the duct runs between floors. I chose Nuaire because of its summer bypass feature which can be manually activated (a must in my house which overheats in the summer), its low energy EC motor and its excellent heat recovery rate, its also very quiet.
I am really pleased with the heat recovery performance, I have installed wireless temp and humidity sensors in the extract and supply manifolds to see how much heat is being recovered, the results are impressive. I also made my own balancing tool out of an aviation anemometer, it works well.
The 50kW turbine we’ve recently added is not counted towards the project – it is not a ‘house’ improvement, it is a farm diversification.
The only subsidies we get are for 2.5kW PV (0.5 kW PV precedes FiTs), everything else was installed prior to FiTs. Turbine was imported direct from China (less than half price, but no subsidies).
We still use some grid electricity, but we also export electricity back to the grid. Overall we generate some 20% more than we consume – and that clean electricity goes in the grid and thus to our neighbours.
Main costs of the home refurbishment were:
Wind Turbine (5kW) £12,000
Solar thermal £4000
Heat Store £1000
Rayburn (reconditioned) £700
The Bore Hole cost £8000
all inclusive of installation
We were very pleased with the thin insulation that Abbotts provided. It definitely doesn’t stop nearly as much heat loss as the thicker insulation (should be up to 300mm for solid walls) but it does seem to take the edge off the heat loss.
The biggest bonus for us has been that a couple of our rooms don’t get much sun and tended to suffer from mould due to condensation. Even the thin insulation is enough to stop the walls getting to the low temperatures at which condensation forms and helps to stop the mould growth.
We also used a product called Sempatap which works just as well but it’s a real devil of a job to install.
In our house, we couldn’t get planning permission for external solid wall insulation (conservation area) and there’s no room inside for the full thickness. Some people use a combination, with internal insulation on the front, more public facade and external on the rear and side elevations (usually rednered over but can have brick slips).
Abbotts Damproofing are very good – their plastering and finishing are brilliant and they’re lovely people. Abbotts is operated by David Prince. His brother does the plastering and his son also works in the business – they’re based over in Derby.
Conventional insulation was used, just more of it. The walls are insulated with mineral wool cavity fill bats (5x100mm thick) available at any Builders Merchant. The original walls are solid 8″ brick. An extra footing was dug out around the perimeter of the building and an additional masonry leaf erected with the mineral wool between. The roof had to be extended to cover this. (It needed replacement anyway.)
The whole project was DIY so there were no labour costs. The house was specially purchased as being suitable for conversion.
Insulated window shutters and doors were installed.
The work did require Listed Building consent. In my case the walls had been lined out with plasterboard about 40 years ago so we could just strip them back and insert Kingspan into the framing. People I know who have either bare stone walls with architraving or original lath and plaster linings will have a problem. I don’t know what the answer is to that unless there’s a thin but highly effective insulation now that can be applied like wallpaper?
Our external wall insulation cost about £28k in total, with a wall area of about 230m² which works out at about £120 per m² internal wall surface area. I got that figure from our PHPP, which is kind of the wrong surface area since it’s a bit too small and doesn’t include the below-DPC wall area except as a thermal bridge reduction. So the figure per m² should be somewhat lower for external metres of wall covered- I’d guess around £100-£110 per m² external wall covered. The house internal floor area is 173m2, if that helps for comparison!
The price was for two layers of cross bonded graphite EPS to 250mm total thickness above DPC, and 200mm single layer white EPS between DPC and foundation toe, with a cementitious parge coat over the walls, mechanical fixings with thermal bridge reducing rondelles above DPC, bitumen replacement adhesive and protection below DPC, armour mesh and render.
It doesn’t include scaffolding- we had the scaffolding up to re-roof and put up the extension anyway. Obviously doing the roofs, extension, trenching and everything else made the scaffolding fairly complex, but even so it was between £3k-£4k on a house which isn’t that tall, but does have a considerable perimeter.
The price for external wall insulation varies wildly, depending on the installer used (I would not go near Westville again with a bargepole!), the supplier and the material used.
The big suppliers for conventional insulation materials include Sto, Weber and Permarock. Permarock were far cheaper for fundamentally the same insulation compared to Sto – although the Permarock render finishes may possibly be less durable on tower blocks.
With the material used, as a guide, the thinner the material for the same overall U value, the more expensive it’s going to be. So broadly, white polystyrene is the cheapest, aerogel is very expensive and grey polystyrene, phenolic and mineral wool all coming somewhere in between. I’ve recently been sent samples of waste wood fibre external wall insulation batts, and also calcium silicate insulation, both of which are surprisingly light and obviously the waste wood is great environmentally, but I have no idea about cost. Mineral wool is surprisingly heavy in external wall insulation form, but is completely impossible to set fire to. EPS will burn, but is pretty impervious to moisture, so poor storage on site isn’t too much of an issue there.
We don’t have meters on the external wall in the white boxes, but even so sorting this one out was tricky. We moved the gas meter 5m onto part of the garage wall which wasn’t affected by the external insulation, then passed the gas pipe between the meter and the boiler through the insulation and a grommet. The water main rises through the utility floor, again through an airtight grommet and the insulation and up to the meter.
We were able to keep the electricity meter within the insulation and airtight layer like the water meter by making most of the garage into a utility room- moving it was going to be very expensive as various things meant that a total rewire would have been needed. An alternative was to make an airtight, insulated box over the meter, but that would have been very fiddly.
If you have recessed white boxes, if there’s space, it may be possible to change them for surface mounted boxes, mounted to the surface of the insulation. You may need an intermediate stage with the meters braced off the wall to get the insulation installed (we did, for the gas pipe): Then it should be reasonably easy to get the pipe or wire through a grommet into the house with a minimised hole in the insulation.
Alternatively, moving gas meters short distances (as in, through a wall) is permissible by an ordinary plumber – not sure about electricity meters, but if you can get one or both into the building and so the airtight layer that would make things a lot simpler.
The AECB. If you’ve not joined the AECB yet I thoroughly recommend it- it’s about £40 per year for an individual, and their guidance and details are really, really helpful and prevented us from falling into about a zillion very expensive pit traps.
Also, the Grove Cottage report gave us a handy starting point. Andy Simmonds is the current chair of the AECB, and it’s his house.
The airtightness case study here should fill you in on the training and testing, and learning process involved. We followed Paul Jennings’ (ALDAS) advice, got training for the build team early on, and I was horribly obsessive about the airtight layer at every stage of the build. Builders with camera phones made this a lot easier, plus living on site and doing lots of the taping ourselves.
The case study of our Passive House here answers this question in some detail towards the end. I think the AECB have (or are developing) a tool to work this one out- including £ per tonne of carbon saved too. We can’t really tell which bit does what by itself – the whole thing together is needed to eliminate draughts and convection currents, for example.
Tough one. We try to focus on the principles of energy saving, right from the basics- what is heat, how is it transferred, what is the difference between airtightness and ventilation, and then look at various methods of improving performance, right from using newspapers to block gaps in ill-fitting windows (which we did before the renovation!) to sealing floorboard gaps, insulating pipes, appropriate loft insulation fitting etc etc, up to the high-end expensive stuff we’ve done. I also asked a whole lot of insulation companies for samples, so I have a big box of brochures, samples, fixings etc suitable for all sorts of different projects- that seems to go down well often. We do feel that we have been really lucky to have the money to be able to do this work, and it is hard to strike a balance between explaining what we’ve done, and sounding smug.
I’m afraid I don’t know the actual CO2 before and after – and given that we have different occupancy, run the house at least 5 degrees warmer all winter, and have a much bigger volume than before, any theoretical CO2 figures are likely to be way off the mark anyway compared to our actual use.
The house ran very cold, no matter how much the 25-year-old boiler was on before the refurb – essentially it was impossible to maintain a comfortable and healthy temperature in winter. The house stays at about 22 degrees C all year now, with an occupancy of 6 rather than 4, about 40m2 additional total floor area and gas bills down from £128pcm in 2011 to £24pcm now – including heating and hot water but not cooking, which is with an induction hob and electric oven.
Electricity use has decreased by a couple of kWh/day on average (about 8kWh/day to about 6kWh/day) but we do now have solar panels with 3.96kWp capacity- the effective increase in use is, we think, due to changing from gas to electric hobs, increased occupancy (increased computer use, particularly when we had lodgers – now we have two more small children, who are too young to use computers much!) and, significantly, the MVHR.
We could, of course, run the house at about the 15 degree C mark to mimic pre-refurb conditions – I suspect we would use essentially no gas all year for heating in that case as the gain from body heat, cooking and bathing would maintain that kind of room temperature through winter – but it would be uncomfortable again!
With the £170k we spent, the house needed a new pitched roof, new flat roof, new sewers (which meant digging up sections of the floor anyway), new windows and doors, new boiler, etc etc- and we built two large extensions, totalling 40-50m2 total additional floor area.
The works also required total redecoration – and even having lifted and saved some of the carpets, lots of paint, flooring, plaster etc was required. So separating out which costs were strictly for energy related measures and which were incidental to other works is completely impossible!
For comparison, we think we could have saved up to £40k max by retrofitting and extending to building regs standards- which would not have given us anywhere near the comfort levels we now have or the bill reduction (including the solar FIT our utility bills are effectively now zero, down from over £200 pcm). In addition, comparable houses in the area sell for enough that the increase in house price should have more than covered the retrofit cost- we went from 3 bed to 5 bed, which in this area makes a huge difference to house price.
Our parquet is reclaimed beech installed using Lecol adhesive onto a concrete base. I cleaned the blocks and installed it and co-opted family to help with sanding and finishing. It is a messy and very time consuming job (scraping bitumen off every block is not funny!) – but the result was a cheap floor that we like. Getting parquet laid is extremely expensive.
We had limited headroom in our house, and so we dug out our old concrete floors in order to insulate without reducing the headroom to below building regs. This is, of course, an expensive option- but with dodgy sewers under our floors it made sense for us.
While wood is certainly a better insulator than tile, it’s definitely not as good as carpet- with or without underlay, or as good as a floating timber floor installed onto an insulation layer. Our cork floored shower room floor feels warmer than the parquet even though the cork is far thinner than the parquet tiles.
If you are not looking to insulate to Passivhaus/EnerPHit standards then using a layer of polyurethane insulation as thick as you can manage considering ceilings and doorframes, or even aerogel or vacuum panels (depending on your budget) under a floating wood floor could make a big difference to how warm your floor feels- you can buy inexpensive sheets of polyurethane insulation from builders’ merchants (or online) in any 10mm-multiple depth you like.
I don’t know if building inspectors would consider the insulating value of wood flooring, but hardwood is pretty dense so isn’t a great insulator.
The most noticeable thermal bridge in our house is the ridge beam, which is, of course, timber (engineered pine rather than hardwood so it should be a better insulator than parquet blocks). Snow melts off our ridge before it melts from anywhere else in the house- including the windows!
We used an external parge coat for airtightness, but regarded the existing internal wet plaster as a kind of helpful secondary mostly-airtight layer- since there was nothing else we could seal the floor slab to!
The first stage of sorting out the roof was to strip back tiles and the lower part of the felt to see exactly what was there at the roof-wall junction. It turned out that, rather oddly, the ceiling binders and roof timbers were sitting on top of a row of bricks which had been mortared onto the cavity. So the builders scraped back the loose mortar and used a polymer modified cement to seal the bricks a little more convincingly to the top of the cavity. This is effectively all inside our airtight layer, but may well make a significant contribution to reducing air movement.
Our other area where cavity closures were needed was the old flat roof (which is now the floor inside the new extension). Here, there was no cavity closure at all- we could see the insulation inside the cavity. the top was levelled with the polymer modified cement then OSB3 strips stuck on with Orcon F glue and Tescon tape between the joists. This took quite a bit of fiddly taping and was very sticky! Again, this is all inside the airtight layer- the OSB and Intello extension wall airtightness joins to the parged brick ground floor wall outside the closed cavity.
For the old pitched roof, the existing rafters were very small (the old ridge beam is 1x4in, which would explain why the roof had sagged and was leaking), but sufficient to attach OSB3 and Intello membrane to. In fact, this probably strengthened the whole thing! Both these layers were taped and sealed to the external parge, and now lie underneath the new (much larger) ridge beam and the wood I beam thingies which hold the 400mm rockwool insulation, more OSB3, breather membrane and tiles (and solar panels).
If we were to do this again now, we would use one of the more airtight fibre board options as it would work out cheaper and much less fiddly than working with- effectively- two airtight layers over the roof and the new extension, which has a timber frame and the same airtightness method.
Our final airtightness reading was 0.3 air changes per hour, so we may have been a bit obsessive- but as I’m sure you’re finding, it’s very hard to judge how airtight something is going to be until after you’ve tested, and it’s really not worth getting wrong!
If it’s possible, try to avoid having to tape around joists or other irregular (or simply not fully sealable) objects- when the tapes are under any tension at all, they tend to shift and unseal themselves over a couple of days as the acrylic glue slips- so the more complicated taping there is, the higher the odds of getting points of failure.
Our MVHR unit is in the loft mounted on the North gable wall , so the ducts to the outside have as short an internal run as possible.
The internal ducts run through the attic space to the upstairs room, terminating in ceiling mounted (extract) and very high wall mounted (inlet) valves.
To get downstairs the ducts drop through the airing cupboard and run in a false ceiling in the downstairs cloakroom then out through (rather obvious and large) boxing again to ceiling or high wall mounted valves.
We spent a long time researching the best way to insulate our suspended wooden floor and came up with the combination as the best option for our parameters. The floor has only about 15cm of crawl space under the joist with a further 10cm depth of the joist itself so we knew straight away insulating from above was going to be the only option. As this meant all the floor boards had to come up it seemed sensible to go with something with the highest insulating value as possible. With this in mind we went for putting zinc screws into the joists 2cm up from the bottom edge and then fitting 8cm Celotex board wedged tight in between with the screws stopping it dropping any lower than level with the top of the joist.
Round the outside edges of the room where it is too narrow to practically fit the Celotex we originally went with recommendations from others and used expanding foam. After the first can we scrapped that idea as it stinks, is incredibly sticky, very expensive and frankly went against our desire to not use chemicals whenever possible. We had bought Sheep’s Wool to cram into the inevitable tiny gaps between the joists and Celotex where cutting hadn’t gone dead straight from top to bottom of the joist so we started experimenting with using it instead of the foam. We’ve spent the winter living with the subfloor we put back down to be sure the combination has worked well before fitting a final floor this coming spring. Although we haven’t had the coldest of winters as yet we’re very happy with the results and can certainly tell the difference in the two rooms we are yet to tackle.
Our property when we moved in was heated by 4 Storage Heaters and the hot water was supplied by the immersion heater as there was no gas main into our house despite it being available in the village. This meant that any options that required radiators to be plumbed in was going to be a major upheaval not to mention expensive so we started to look elsewhere.
We were already aware of Air to Water Heat Pumps but as we didn’t have radiators this was of limited interest but it did lead us to the Air to Air option which combined with PV Solar Panels has proven to be a very cost-effective installation that suits our needs.
The answer is yes, although the caveat we would place on this is that this winter just gone was not particularly demanding on the system and, being air based, insulation to trap in the warmth/air is of the utmost importance.
The outside unit is where all the work happens in terms of noise so it does emit a hum which isn’t intrusive but likewise is not silent. It isn’t loud enough to annoy us or neighbours and it also isn’t continuous as it merely works when it needs to.
The indoor units simply blow out the air which you can control the speed of so they can be very quiet or a little noisy depending on how enthusiastically you run them. Used sensibly (i.e. leaving on to give a constant trickle of warmth) has them running very peacefully and backed up by the woodburner we’ve been really happy.
We wouldn’t hesitate to recommend the company we used – Delta Refrigeration. We spoke with Michael Cosham there. It was his son that installed our system along with a team and it was all done in one day very quickly with no fuss.