SuperHome Q&As

SuperHomers are often happy to respond to questions about their refurbishment project by email between Open Days. Here are some of these Q&As to date. On each of the homes on the SuperHome database you’ll find a contact tab enabling you to email the homeowner.

SuperHome"

London, Islington, Hargrave Road

House Category:
SuperHome

House Type:
1860 End of terrace
Carbon saving:
62% - SuperHomes Assessed
Installed Measures:
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What thickness of aerogel insulation did you install?+

It was approximately 3cm thick in a single layer but clearly made up of sublayers sitting together. It was not a board.

In terms of quantity used, as very rough estimate it was the larger part of three sides of a three-storey house approx 8m x 9m over two storeys and 8m x 5m on the ground floor (because of the flying freehold) and the height is approx 10m. There are sections where Aerogel was not used, eg on the outside wall of the entance hall where instead we insulated on the outside.

Did you avoid drilling through the aerogel insulation?+

Yes, we were told not to drill into the Aerogel as the fibres would bind around the drill bit.

SuperHome"

London, Kingston-upon-Thames, Willingham Way

House Category:
SuperHome

House Type:
Late '60s ex-council wood-framed end-terrace house
Carbon saving:
62% - SuperHomes Assessed
Installed Measures:
, , , , , , , , , , ,


Which builder did you use for your retrofit?+

David Mansell and Ross Woodland are the builders that I use. Email david[@]mansellandwoodland.co.uk. Some plumbing stuff I organise via other routes because my next-door-but-one neighbour works at a plumbers’ merchants! We upgraded our existing cistern to dual flush.

Which single room heat recovery units did you use in the bathroom and kitchen?+

The units I use are both Vent-Axia and if left to run all year would be about £2 in electricity charges. (The bathroom one is only on half the year though!) The units are: Bathroom: HR-25 (with humidistat) and Kitchen: Lo-Carbon Tempra

How do you go about installing a single room heat recovery unit?+

Builder or DIY with a core drill.

SuperHome"

London, Southwark, Choumert Road

House Category:
SuperHome

House Type:
1870s 3 storey semi detached house but now with side passage covered to make almost terraced, to reduce heat loss
Carbon saving:
78% - SuperHomes Assessed
Installed Measures:
, , , , , , , , , , , , , ,


Any advice on where you went for your sash windows?+

I went to a local carpenter in East Dulwich, Runcent. Internet companies tend to be 2 to 4 times more expensive. Generally speaking there is little point going above Building Regs standard double glazing as the savings do not pay off the increased cost.



Which wood stoves did you fit, how efficient are they and how much did they cost?+

There are two stoves in our showhome.
1. The all signing all dancing 93% efficient Xeoos Twinfire 5kW, equipped with 150kg of thermal mass (hence the larger output), and fully direct air feed compatible, costing around £3600 for the device alone.
2. The 4kW Burley Debdale is much more cost friendly device (£550) boosting 89% efficiency, still direct air feed compatible, no thermal mass unfortunately so recommend installing it in an exposed brick/stone hearth and surround.
For a half way house between these two devices (cost and functionality wise) I also recommend DanSkan stoves (only those with their air box technology however), they have some fancy control and lovely modular thermal mass.

 

 

What did you consider when choosing your wood burning stoves?+

Stoves require air (oxygen) to burn and traditionally take this from within the room. Modern devices require three air streams, Primary, for the bulk of combustion, Secondary, to control the rate of burn and Tertiary, as a screen wash to keep the glass clean. Broadly speaking a wood burning stove is a bad item to have within a property if it takes any of the three air streams from within the room due to that massive cold infiltration it causes both within the room and throughout the rest of the property(especially when alight). This is where direct air feeds  (or outside air supplies) come in… Many devices are compatible, allowing a small pipe to be connected via a spigot on the back or bottom. This pipe either pops through the wall to the external leaf with a grill fitted or lead through the hearth when on a party wall and lead to the nearest air brick. Some devices are partially room sealed, so be careful to select only totally room sealed.

The stove should be 5kW or less. Above this you start to require a primary air feed, meaning a hole in your wall. Additionally over sizing devices is a really bad idea considering the first 20mins and the last 20mins of any burn are the most inefficiency. If your device is oversized then you will simply push these two phases together, adding in a deal of uncomfortable over heating to boot. Most rooms will have radiators sized between 1.5-3kW, designed at -3°C or -5°C exterior temperatures. It doesn’t make sense therefore, to put a secondary heating device in the same room with over twice the capacity.

In rural areas you require a device with smoke control exemption, else you can only burn smokeless fuels which are both expensive and awful for the environment.

Modern devices can achieve amazing performance levels, yet people still seem happy to purchase very inefficient old technologies. The sweet spot is 80%, above this you have a marked reduction in maintenance; less chimney cleaning, ash disposal and glass cleaning. Below 75% I seem to find lighting the stove to be more of an issue as the air flows within the chamber or not optimised. All in all more hassle than it is worth, efficiency matters.

A nice to have element is inclusion of thermal mass. This concept is simple, a proportion of all the heat generated is absorbed into the surrounding thermal mass rather than all kicked out into the room. This will enable you to burn for longer without having to starve the flame of oxygen to reduce its output. It will also mean that after the stove goes out it will still provide heat to the room for hours afterwards.

Who did you use for replacement windows and what was the cost?+

We used units from Estonian manufacturer Viking Windows who predominantly provide high specification units to the Nordic Market.

You can review their range below. To give a really rough idea of the cost differential between the products; the SW11 and DK88’s are similar in price at around 20% more than the Viking-12 and 10% less than the SW14.

Viking-12 (Uw = 1.2 W/m²K) – Outward opening double glazed unit

SW11 (Uw = 0.97 W/m²K) – Outward opening triple glazed unit

DK88 (Uw = 0.72-0.81 W/m²K) – Inward opening triple glazed unit

SW14 (Uw = 0.68 W/m²K) – Outward opening passive house certified unit

SuperHome"

Manchester, Salford, Hersey Street

House Category:
SuperHome

House Type:
Victorian mid-terrace c.1900
Carbon saving:
69% - SuperHomes Assessed
Installed Measures:
, , , , , , , , ,


How airtight did you manage to get your terrace house? Did you do an air test and if so what result did you get?+

I didn’t do a final air test, but had one done once most insulation and airtightness was done, and  the result was 7.85 m3/m2/hour (that is the UK method for measuring leakiness) which translates to about 9.3 air changes/hour (m3 of air compared to volume of house, which is the Passive House method). This was still leaky because there was a large leak from an open chimney flue and a few other places, so if I redid it, I reckon I’d be somewhere around 3-5 air changes – which isn’t enough. I now know you really need to be somewhere around 1.5 air changes an hour for the MVHR unit to operate efficiently. So my air tightness wouldn’t have been good enough, it needs a lot of attention to detail.

Which MVHR unit did you choose?+

Originally I installed the Xpelair Xcell300. I wouldn’t choose it again, for various reasons. For example, the fan speeds cut out once you reduced it to its minimum, which was still too fast for my house volume. You need fully programmable fan speeds ideally as well as one that is efficient and this unit didn’t come with a 3 way switch as standard. Also the ducting didn’t fit together properly!

In 2013 I installed a Brink Sky300 unit (available via phstore.co.uk) which has the following advantages:

  • Slimmer unit so can fit in false ceiling if needed
  • Self-balancing fans in the unit itself (keeps air flow the same in both in case one starts to clog up over time)
  • System of manifolds with air restrictors – as long as it’s designed right, the air restrictors at the manifold ensure fixed air flow to each room and makes people fiddling with the terminals less of a problem
  • Semi-flexible ducting system with airtight joints (smooth inside, corrugated outside) is much easier to install in retrofit, and slimmer so boxing out doesn’t seem so obvious. Manifolds have to also be boxed out though, so that’s a downside.

This is not to say that the Brink is without fault – there were a few installation issues (e.g. there is a simpler 4-way control switch which can be connected in place of the digital one = simpler to use potentially, except that when it comes time to hoover the filters, the red LED light cannot be switched off without connecting the digital controller to the MVHR unit… in other words better to just install digital controller from the outset; there were also one or two issues with duct connection to the manifold). I’d given feedback on all those points before, so I don’t know if they’ve improved their system yet.

You definitely need to correctly specify the unit given the air flow needed, and the exact amount of ducting/bends will affect the flow rate to each room and this needs to be calculated. So best to get this all designed for you.

Does your wood burner have a sealed air inlet (i.e. draws air from outside airtight envelope)?+

No it draws air from inside the house, which works well as air comes in via ventilation system, so there doesn’t seem to be a problem in terms of O2 levels.

I want to fit internal wall insulation to our solid walled 1930s semi, would you have any general advice?+

I’d recommend doing an energy analysis on the house first and then fit the wall insulation work into a retrofit project that might include other measures while you’re at it. This is because wall insulation of external-facing walls will most likely be a major contributor of heat loss and carbon emissions, but it might not be the biggest factor. If space heating demand or carbon emissions are your main driver for wanting to do the work, then you need to be sure you’re targeting the right thing(s). Also depending what your goals are, if comfort is a big driver for you wanting to do this work, then airtightness and ventilation will be a major contribution to feeling comfortable, not insulation alone.

Also if you’re doing internal wall insulation, you really need to get the airtightness right on the internal face – any gaps will mean moisture can get through and cause interstitial condensation on the cold original wall surface leading to mould (e.g. from modeling and field tests, we know that a typical 1mm gap in air membrane that is 1m long can allow 360g of water to condense – this is with conditions of 20 deg C inside and 50% relative humidity, and 0 deg C outside with 80% relative humidity). So it really kind of links in to other parts of a retrofit and I’m not sure it should be done in isolation without airtightness/ventilation.

What was the product name of the gravel that you used in the crawl space?+

The gravel was called ‘MOT’ – don’t know what it stands for but you get it from builder merchants like Travis Perkins. I put down about 5cm depth all over the crawl space, which equated to about 4.5 metric tonnes! I don’t know exactly what type of infill it is, but it tends to soak up moisture a bit, so it helped to make a dry-ish base on which to stand and sort out my joists before putting the DPM down.

How did you feel the gravel combatted some of the humidity levels in the house?+

The humidity was sorted overnight after the plastic sheet went down, even with all the floorboards up and joists exposed. I know this because I’d get condensation on the windows every morning and the morning after there was none. It just showed that a lot of moisture was coming from evaporation from the ground. Also I know this because the underside of the original chipboard floor was covered in white mould except for the place where it went over the base of the hearth – here there was no mould. Again confirming that evaporation from ground was a big issue.

Did you find a solution to damp suspended floor timbers and crawl spaces?+

After some years of monitoring wood moisture content for my joists, that had been made fairly airtight and insulated with Kingspan, I’ve finally figured out a combination to ensure they stay healthy. See here for more details.



Who did your external wall insulation and what material did you use?+

Westville carried out the work on my insulation; externally & inside in certain areas. Phenolic foam is the preferred option unless you go for the super thin Aerogel insulation.

SuperHome"

Oxford, Headington, Stapleton Road

House Category:
SuperHome

House Type:
Edwardian 3 bedroomed semi detached
Carbon saving:
68% - SuperHomes Assessed
Installed Measures:
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Which installer did the internal and external wall insulation?+

We were lucky in finding an installer for the internal wall insulation through a contact. Unfortunately he’s no longer in this business. We did recently try to get a quote for a bit more internal insulation, and did find one suitably experienced builder who might have been prepared to do it – the only one on the ‘approved’ list for Pavatex, the insulation material we chose. We got his contact details from Natural Building Technologies.

However, we didn’t end up getting the work done due to timing problems, and have postponed getting this done. It might be easier to find somebody to use more conventional insulation materials – but certainly there are very few working with Pavatex (a wood fibre insulation).

We used a different contractor for the external wall insulation – Merl Cunliffe. This was also Pavetex. I haven’t been in touch with him since he did the work at our house (approximately 6 years ago) but assume he’s still in the business. There are more details on our renovation here which include Merl’s contact details.



How did you get the insulation for just GBP 50? What was involved in installing it? Is there anything about it that people might not anticipate, for example noise or sagging?+

This was a wooden floor put onto of a concrete base. ‘Battens’ of 4″ x 2″ were laid and the  flooring nailed to those lying across them, which left 2″ of gap for insulation, into which was put 50mm of polystyrene sheet, which is very cheap, hence £50. There’s no issue with sagging of course.



Did you fit both external and cavity wall insulation? What about internal insulation?+

If you look at the photos of the house the cream walls are all external wall insulation which has worked really well. For the brick walls, which make up the bulk of the house, we were lucky that the bulk of the house is a cavity wall. This was unusual in the Victorian times, but after a bit of research I found out it is not unheard of. The challenge was that there was no standardized way of building cavities in that era so there was a fair effort involved in checking out the cavity to make sure there were no nasty surprises later. Here we had graphite treated polystyrene beads injected as they are the most insulating breathable insulation (that we could have injected). The ‘best’ approach to solid walls is very case specific but tends to come down to how much you like the outside of your house versus how much space you can afford to lose inside. In Victorian houses this can feel like catch 22!

In general loft insulation & draft proofing (including open chimneys) are often some of the most cost effective areas to improve. If your floors are suspended then this is also another possible area for attention.

Do you have any tips for insulating between floor joists?+

There is a pretty comprehensive guide to floor insulation on the SuperHomes site that I’d recommend. We only have a small area of suspended floor but this is similar to the drawing marked ‘Detail for insulation beneath suspended wooden floor’ but using rock wool.

In answer to your question, good practice would be to have a vapour barrier (or vapour) control layer between the insulation and the room.

Personally where space is not a key constraint, I like rock/glass wool as it is breathable, won’t rot, can dry out in case of problems, good in case of fire, lasts forever, fairly cheap and doesn’t take much energy to make in the first place. The question of which insulation is ‘best’ is application/case sensitive and rather subjective so you may well get other differing opinions.

I’d recommend thinking holistically about improving the house and come up with a plan for which elements you aspire to improve. This can help you avoid having to redo work and combine any similar jobs to save money. With this in mind you may find this Energy Saving Trust tool useful.

SuperHome"

Shrewsbury, Bayston Hill

House Category:
SuperHome

House Type:
1950's detached concrete bungalow
Carbon saving:
72% - SuperHomes Assessed
Installed Measures:
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Is mechanical ventilation with heat recovery noisy?+

I have installed an Itho MVHR system, which runs very quietly.  It
can only just about be heard, when lying in bed and everything else is
quiet.

Prior to the installation I worried about fitting the MVHR unit in the attic
with possible vibration and noise as a consequence.   These problems
didn’t materialise, but the position enabled me to run all the ducting above
the ceiling in the bungalow with the inlet for fresh air and outlet for the
used air operating through vent tiles in the roof at 2m distance from each
other.

 

 

Does the fresh air from the MVHR unit feel cold or draughty?+

When Hay Tor was photographed with a thermal imaging camera the outdoor temperature was 3C, we checked the freshly distributed air at 18C after going through the heat exchanger.

Since our roof is insulated below the rafters there was no need to insulate the
ducting in the attic, which would be necessary, if the insulation is located at
ceiling level.

SuperHome"

Shrewsbury, Ryton Villa Farm

House Category:
SuperHome

House Type:
5 bed, Georgian Farmhouse
Carbon saving:
86% - SuperHomes Assessed
Installed Measures:
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How happy are you with your 11kW Windhager biomass boiler?+

We are very happy with this boiler. Last year we burnt just 2 tonnes of pellets in our 5 bed house. The boiler is relatively small in terms of output for a large property of this type so we made sure our house was very well insulated.

Do you feel you struck the right balance with MVHR in terms of ventilation?+

We have had MVHR before in a previous house and therefore know the benefits in terms of comfort and fresh air.

We are ware that for MVHR to work best the house needs to be very airtight which is hard in an old property. However we took the view that we were removing the draughts inherent in old properties through draughty windows and we were also going to use a non breathable insulation so we felt MVHR was necessary to compensate for this. We are very happy with it although it is questionable how much actual energy it saves in an old and not particularly airtight house.

How well has the lime render worked with the external wall insulation?+

We used Kingspan K5 EWB external insulation because we had  limited space under the eaves to put insulation so wanted the maximum benefit for the available space. Keim Render was the only lime render who support using their product on that insulation. We chose the lime render because of its appearance, not because of breathability, as the insulation we have used is not breathable. If you have space a breathable insulation, such as Pavatherm would be better with Lime Render but would require double the thickness for the same thermal improvement.

SuperHome"

Steeple Claydon, Meadoway – SUPERHOME 150

House Category:
SuperHome

House Type:
1970s End Terrace, two floors
Carbon saving:
62% - SuperHomes Assessed
Installed Measures:
, , , , , , , ,


Why did you switch to an air source heat pump for space heating?+

After the gas fire was taken out, for a time we heated the house using a 2kW wall-mounted heater. During December and January we used an average of 27kWh per day. In the previous winter when we used the 2kW electric fire we used 34kWh per day. The heat pump is rated for 0.7kW. On the face of it 0.7kW, to heat a house? Could it possibly be big enough? In our experience: yes.

We knew from past experience that the old gas fireplace in the living room could adequately heat the whole house without using the radiators, so I was fairly confident that a new source of hot air in the living room could do the job. And so it has proved.

The floor area of our house is 98 square metres and the volume is 225 cubic metres. The old gas fire our heat pump replaced was rated at 11.7kW. So 0.7kW replaced 11.7kW (although it doesn’t heat water). A huge gain in efficiency I think!

Since we installed it, our electricity consumption has gone down. Last year we got by on just under 7,000kW hours, and no gas at all.

Will a heat pump work in a detached 1935 home with solid walls?+

Thanks for your letter. The first thing I note is that your house is much larger than ours. Our floor area is 98sq metres with an internal volume of about 252 cu metres. The next very important difference is insulation. We have cavity wall insulation, and in the case of the bathroom, and above the stair well, internal wall insulation as well. Our internal wall insulation is plaster board backed with 42mm of foam insulation. I have also done my best to make the house as airtight as possible. We also have about 250 to 300mm of loft insulation, and of course double glazing, and an insulated front door. All of that effort went into minimising our heat losses before we worried about what heating system we needed. During the summer, from say early in April to mid to late September we switch the Heat pump off completely. However, we have used it for the odd day or two as a cooling unit for the occasional heat wave. Try doing that with a gas boiler. I think your best course of action is to insulate the house as much as you can before doing anything else. A book that I found useful was the Green Building Bible.

Does your air source heat pump do the job in winter?+

Our entire house has been nice and warm since we installed our air source heat pump in December 2011. We leave it switched on 24hrs per day and it keeps on blowing out warm air at about 35 degrees-even on below freezing days. After being off for the summer we switched it on again on in the third week of September.

We have never used any additional heating, except for a 300 watt towel rail in the bathroom. Even on below freezing days, it keeps blowing out warm air at about 35 degrees. Our house is open plan and the heat from the living room makes its own way upstairs where it keeps all the bedrooms warm too.

Is the air source heat pump noisy?+

The indoor unit is very quiet, and the only noise that the outdoor unit makes is the sound of the fan blowing air out, but you have to be standing very close to it to be aware of it. Our cat sometimes stares at the indoor unit for long periods, so it’s possible that she can hear something that we can’t.

Was the air source heat pump easy to install?+

Our installation was probably very simple. The outside unit is just about 150mm above the decking and the indoor unit is the other side of the wall about 1,500mm vertically above it. So, no long pipe runs, and no need for ladders or scaffolding. We got three quotes,  one for £8,000,  one for  £2,100, and the one we accepted for £1,200, plus the lower VAT rate for qualifying renewables installations.

Who supplied your air source heat pump?+

Our heat pump was supplied by:
ACS (UK) Ltd
Tel: 0800 085 4737
info@airconsolutions.co.uk
www.airconsolutions.co.uk

The model we have is a Mitsubishi rated at 1kW. Although rated at 1 kW, my best estimate is that it uses about 0.5 kW. Even on a cold December day we rarely use more than 25kWhrs per day , which includes cooking, hot water TVs etc. We don’t use any gas. Our house is open plan which means that the warm air goes up the stairs to heat the bedrooms, we have no control over how much heat goes upstairs but in spite of that it all seems to work very well. We are very pleased with it and our electrical consumption has gone down since it was installed.

How do you size an air source heat pump and is an annual service required?+

I can’t claim any expertise about heat pumps and we accepted the recommendations of ACS (UK) Ltd with regard to the size and make of machine. So far it has performed very well and we are very pleased. They do offer a maintenance package at a cost of about £150 per year. They also suggested that we needed this package to comply with certain regulations, I looked up the regulations and discovered that our machine was too small to be covered by the regulations, frankly I thought they were trying it on so I declined their servicing package and clean the air screen/filters myself.

SuperHome"

Stockport, Bramhall, Manor Road

House Category:
SuperHome

House Type:
1920's detached
Carbon saving:
74% - SuperHomes Assessed
Installed Measures:
, , , , , , , ,


+


What difference does it make if you clean your solar PV panels?+

I noticed a 2kWh difference in a day from cleaning my panels at peak in the summer last year. I deliberately chose 2 consecutive days where the forecast was for virtually unbroken sunshine. Until then, I had not cleaned my panels, so will be keen to see what the annual numbers are this year – I plan to clean them more frequently.

SuperHome"

Tyne and Wear, Whitley Bay, Paignton Avenue

House Category:
SuperHome

House Type:
1926 Mid terrace
Carbon saving:
67% - SuperHomes Assessed
Installed Measures:
, , , , , , , , ,


Why did you go for a Morso wood stove?+

I went for the Morso (Squirrel 1412) after some internet research – based on the reputation of company, their experience over many years in Denmark and at that time not many manufacturers were able to supply Defra approved for use in smokeless zones. The stove was also appealing in that it is traditional cast iron rather than pressed steel. When the fire dies down cast iron keeps its heat for much longer than steel.

Why did you choose the 4kW model wood stove ?+

I choose the 4kw output based on the size of my room (the smallest stove they produce)  In actual use it heats the whole house somewhat with the room door left ajar.

Who installed your wood stove and would you recommend them?+

I bought it in 2011 from ‘Stangate Stoves and Cookers’ who are based in Lemington, Newcastle upon Tyne and it was installed by one of the contractors they recommended ‘Fire & Stove Solutions’ (Dave Anderson Mobile: 07891544740).  Yes I would recommend them.

How much do your pay for wood fuel and where do you store it?+

I get my wood from a mental health charity based in West Sleekburn, Northumberland – ‘The Woodfuel Centre’.  £85 per cubic metre of hardwood.  I use about 3 cubic metres per year.  Not that cheap but its sustainable! Clearly if you can get your own wood for free the running costs will be around zero! And watching the flames through the stove window is a lot more relaxing and entertaining than staring at the TV!

It is a terraced house with a passage way between so wood stores nicely there in a good through draft.

How much do your spend on gas and electricity?+

My current annual bill for gas and electricity should be about £570 on the Cooperative Energy tariff.

How much water do you use?+

I switched to a water meter on purchase of the house so don’t have a reduction cost but current useage about 42 cu metre annually.

SuperHome"

Vale of Glamorgan, Penarth, Clive Place

House Category:
SuperHome

House Type:
Two Storey, detached, built in 1948
Carbon saving:
81% - Remote Assessed
Installed Measures:
, , , , , , , , ,


+


Is there a risk of interstitial condensation with external wall insulation of a U value better than 0.5 on a home with cavity walls?+

Rob’s Building & Environmental Consultant, Ken Neal, answers this question thus.

Interstitial condensation occurs where the dew point falls within the construction thickness.  This will almost always be the case in cold weather.  Where this occurs and in what material is where the problem can lie.  With a badly insulated structure the dew point will form close to or at the inside face of the construction causing damp and this then causes harmful mould growth.  With a well insulated structure the dew point is well into the construction depth and so there is less of a problem with dampness and mould growth at the inner surface.

This can cause a different problem, though.  If the outer surface is a soft porous material such as old brick and the weather is freezing the interstitial condensation occurring in the outer layer of brick can freeze and spall off the face of the brick.  This can happen with cavity insulated structures or with internally insulated structures.

With the external insulation system that I specified for Rob’s improvements the dew point falls well within the outer layer of insulation.  Because of the make up of the insulation material the moisture vapour cannot move through the insulation to the dew point so it stays warm and in the form of vapour.  Where the vapour moves through the joints between the boards there can be condensation but it is harmless and drains away eventually.  Any other excess vapour is removed from the house by the ventilation system accompanied by the low level of heating required by the highly insulated structure.

Internal insulation systems commonly used in older and listed properties have to be very carefully specified and detailed to prevent the occurrence of cold bridging and moisture movement through the insulation.  This is to prevent the build up of moisture in the outer layers of the construction and possible freezing damage.  These insulation systems, while being possible to construct on a DIY basis, need to be properly designed and detailed by an “experienced” professional to avoid the many pitfalls that can occur in a badly designed and detailed  job.  A DIYer has as much experience as many builders in this type of construction and are more likely to follow the plans and get it right than many builders who will do it the way that they have always done it and get it horrendously wrong.  There needs to be a huge educational push in the building industry to show most builders how to work with modern insulation materials.

I have not read the ‘Breaking the Mould’ report and if it cautions against U-values of less than 0.5 I am not going to bother.  U-values of around 0.1 are commonly used on the continent and occasionally used here, as was the case with Rob’s house, without any problems.  Where problems can arise are when systems are not properly designed, detailed and built.  That is not a problem with high levels of insulation but with bad building.  We need to address bad building not the required high levels of insulation.

A house with a best insulation value of 0.5 is more likely to suffer damp problems than one with a better U value because the cost of heating such a structure will mean that it is often colder than it should be, inviting surface condensation and mould growth.  It will often be kept more airtight to avoid cold draughts and hence build up a higher level of water vapour within the structure.  Such a property would commonly have double glazed windows which will prevent condensation on the glass.  This will, however, throw more water vapour onto the cooler walls exacerbating the mould problems.