Our boiler is called a “MCZ S.p.A. Musa Hydro 15”.
It is quite noisy, one of the main disadvantages I would say. There is a fan inside the boiler which does make a noise. We opted to have our boiler fitted in what was a utility room for this reason. For us this has been an advantage, as a formerly unheated room has become a nice new living area. The boiler emits a lot of heat, so it would be a shame to waste that, although I gather some people do have them in garages etc which would solve the noise issue. I don’t think it’s louder than our old oil boiler; I just wouldn’t want the noise in the living room. It looks lovely – you can see the flames, and it is very atmospheric.
We used two bags of wood pellets per day most days during the winter (20kg), which cost around £5.10 per day, for 96 kWh of heat. On the coldest days it was 3 bags. We were quite frugal with our use of heat and kept the house fairly cool. However we do inhabit it 24/7. We have not used any wood pellets over the summer as we have solar water heating, topped up by an immersion heater.
We had to have a big water tank/heat store installed. The boiler heats the water in the tank, which then feeds the radiators, rather than the water going straight from the boiler to the radiators. Something you might need to consider, especially if you’re short of space. For us we basically gained a room by moving the freezer to the garage and the washing machine to the kitchen, so we’ve easily got used to the big water cylinder in the corner. You’ll also need to consider where to store the wood pellets. They are bulkier than the equivalent fuel as oil. We’ve had four deliveries over the last year, each delivery was one pallet with 96 bags each weighing 10kg.
We have had the boiler for a year and have spent £940.75 on 3,840 kg of wood pellets. This compares with £904 and £857 for the last two years we used oil. So it’s been slightly more expensive than oil was, however oil had more than tripled in price over the previous decade. Also the Renewable Heat Incentive is due to be introduced soon, which will pay a large proportion of the cost of wood pellets. I’m not sure exactly how much it will be yet, but last time I looked my best estimate was that we would get over £600 per year for 7 years. This is despite the fact that we have already had a Renewable Heat Premium Payment towards the cost of the boiler. The cost of installation was around £10,000 and the grant was for £950. I have a feeling that new applicants will not get a grant, but will get a higher rate of RHI, but I may be wrong. Anyway, the RHI definitely contributes in a major way to the cost of installing a biomass boiler.
The architect we used is based in Canterbury and is called Conker Conservation. A lot of the materials came from Ecomerchant in Graveney.
The answer is that we did take 10cm of pavement, for which we got planning permission. The key was to talk with the planning dept during the process so the application didn’t come as a surprise.
Our external insulation is the German Sto system, installed by Beaumont Facades.
We are in the sixth winter relying on the air source heat pump and I must say it is a resounding success. We just replaced a gas boiler in an old central heating system with a ground source and an air source heat pump. The ground source works well but unfortunately not enough pipe was put in the ground (double loop to 57 metres). The expense of adding more loops was far higher than experimenting with air source and we made the right decision with air source. The ground source is great for a boost on very cold evenings though.
We back up our heat pump with a wood stove in sub zero conditions. This also heats our water for showers etc.
The easiest way to heat water from multiple sources is to use a tank with multiple heat exchange coils. Tanks with 3 coils are easily obtainable. My Superhome uses the original tank with one coil.
I use solenoids in conjunction with time switches and thermostat to control flow from each device though the woodstove is always free flowing to the tank from the back boiler, so when the hot water is heated from the air or ground source heat pumps it acts as an extra radiator. It all works very well and I can heat water 6 different ways.
I cannot use convection to circulate hot water from the air / ground source pumps or solar water heating. As the pipes go from the garage to the attic, entry is well above the tank. We use 4 pumps in total with 2 valves and one timer / 1 thermostat. Only 1 pump is ever on at a time, consuming 20 watts. I did start to develop a bespoke adaptive controller using a PIC chip but this proved to be unnecessary.
We used an accredited Permarock installer. Recently we have used Joyners who were good. The external wall insulation system we used is Permarock Platinum (250mm neopor type EPS).
We have lived with biomass for six years and the day-to-day experience is identical to living with a gas-based system. It is largely hassle-free. If you can get the Domestic Renewable Heat Incentive (Domestic RHI) to pay for the costs then it is a very economical too as the fuel costs are now lower or comparable to gas. We entered the venture because we knew statistically that biomass would have the biggest impact upon carbon footprint per unit of money spent.
The downsides are several folds: the industry is young in the UK and it is hard work finding a professional to look after your system. So I do the annual service myself. The boiler physically takes up a lot of space. With fuel storage & heat store this is the space of a family car. We refuel from sacks which can be a hassle. If you are physically fit this is OK. If not you can get deliveries blown into a large tank then fed to the boiler automatically. Finally such a beast might put off a buyer to your home if you wish to sell-up and move on.
So, to answer your question: would we do it again? Yes – certainly if the RHI had applied. A no brainer. If we had the space we would have got bigger storage with auto-feed so that the running would be hassle free. If there was a professional out there to care for the boiler that would be weight off our minds. The RHI would cover the costs of such after sales care and service. So if we did it again today it would be a different experience. Six years ago we were at the bleeding edge and suffered some inconvenience and cost subsequently.
Look at it a different way: what would be the alternatives? A ground source heat pump would require ripping up floors and garden. We did a lot of research and inserting a heat pump would require too much disruption to our lives. I was not happy with the fact that it used electricity. Your home would also need to be well insulated for heat pumps to be effective. We could have just stuck with gas but that would not have given us the low-carbon impact we wanted. We wanted to be off fossil fuels completely – in essence to re-localise and get ‘off-grid’ – get more resilient. Our choice reflected a certain philosophy to life. In the end it can come down to ambition which is why we made that choice six years ago before the RHI.
Sometimes it helps to be passionate about something.
The boiler fitted is a Biotech, the fitters were Sterland and Elgar. I chose them because their main man, Bob Smith, seemed to know his subject far better than some of the other ‘salesman’ types who came representing larger companies. They are based in Warwickshire. The work was quite complicated as retrofits generally are. The house is now warm, this was something we never experienced before as the oil was prohibitively expensive.
As far as insulation is concerned, because we did not do a complete renovation when we moved in 18 years ago we have added bits of insulation here and there so there are many different types used, and in fact I am always looking at upgrading a bit somewhere or other. However it seems as though you can’t beat Kingspan.
We did have a ‘grand plan’ at the outset to do a retrofit PassivHaus. Our own Development team had been trying to complete a PassivHaus newbuild scheme for some time but never managed it, so working with them we decided to see how far we could go with an existing home. To our knowledge this hadn’t been attempted in the UK before the Retrofit for the Future competition came along.
We didn’t engage a specialist advisor specifically on PassivHaus, although we did appoint a Merseyside architect (Alan Larrossa) who worked closely with ourselves and Maple Timber Frame in developing the scheme.
They were very keen to do it!
I’m very pleased to report that we haven’t had any incidents of condensation in the home since it was finished. The Mechanical Ventilation Heat Recovery unit in the house is one key part to ensuring this. Good design, tight control of the refurb process, good contractors and good products are all essential to achieving a good outcome. In our case, involving the residents at all times was very important – they attended every site meeting during the project so knew exactly what was in the property and how to use it from day 1.
If you replace the single glass in your sash windows with double glazing you will have to adjust the sash weights as the double glazing is twice the weight of the single. I suggest you look in the sash pockets and see how much depth you have below the existing sash weights. You will need to calculate the additional weight you require and either add to the existing weights – which are most probably cast iron. If you cannot get the additional length of cast iron into the existing pocket you will then have to see if you can fit lead weights in – these are heavier than cast iron – so you need less depth for the weight. Lead weights are however more expensive. In our windows we ended up replacing all the cast iron weights with new lead ones.
If there is damp you should deal with it before covering it up.
We installed the cork insulation ourselves. It wasn’t difficult, but you do need some basic building skills and scaffolding. The cork insulation has been really effective in reducing heat loss and improving internal comfort of our house.
However, I must state that our use of this cork is experimental as it is supposed to be rendered. We didn’t render it because it would have been to stark a contrast with the rest of the house. Our cork is also on a very sheltered wall.
We got our cork from Environomix. The fixings we used were from ejot.
I did have an interstitial condensation calculation done to check the dew point would be on the right side of the wall.
What we did with the cork on the north side of house was experimental as it is supposed to be rendered. It is essential to get an interstitial condensation risk analysis done for any walls that you are intending to insulate to ensure you are not going to get a dew point on the inside of the walls. The company selling the cork should be able to do this for you. We fitted the cork ourselves.
Note that if your current walls are damp you really need to understand why this is happening before you cover them up. And then let them dry out before installing any insulation.
We did not use any vapour barrier – but we did have a condensation risk analysis done of the make up of the proposed insulation.
We fixed the cork using proprietary external wall fixings from Ejoit – which are thermally broken and expanding.
The recommendation from the cork people is that if used externally the cork is rendered. We chose not to because our external wall faces due north (thus very little UV degradation) and is very sheltered by the neighbouring building which is only 1000mm away. Our cork installation is effectively an experiment and so far it is performing very well, but we cannot and do not recommend our approach for any other building. So please, if you choose not to render, be aware that it is at your own risk.
Internally we fitted either 120mm in two layers (70mm and 50mm) with staggered joints and in some places it was 150mm thick in just one layer (this is because we had cork left over from the external wall to use up).
We did not remove the existing plaster from the walls. We fixed the cork directly to the inside plaster.
I can’t really say I would recommend cork over wood fibre or insulated plasterboard as they all have a slightly different properties – eg thermal conductivity, embodied energy, easy of fixing etc. but I can say that we are very happy with our internal and external cork wall insulation and I would use it again.
But please note that the way we installed our cork insulation was rather experimental (I.e. No vapour barrier internally , no render on external cork). It is not what the manufacturers recommend/suggest. So we cannot and do not recommend our approach, if you decide to follow our approach please be aware that it will be at your own risk.
100mm of polystyrene was used for internal wall insulation. The results from monitoring for interstitial condensation show that moisture levels are within acceptable limits.
The monitoring at Bertram St was carried out from Jan 2011 – Dec 2012.
We have not used an architect on these works and had one builder to do the insulation, mouldings, kitchen double glazed window and some plumbing changes. I used a different contractor (previously) to do the new boiler and secondary glazing was done in two stages by Everest. The final work we had done was a new shower room by another company. So a lot of different stages and contractors because of different pressures and our own movements. I feel that to use just one builder/contractor might have been better and cheaper.
I am an energy consultant and have quite a lot of practical knowledge about buildings and energy and so knew what I wanted and did not need another advisor. There was no remodelling of the (small) flat. For the wall and ceiling insulation I did use a contractor who had done this sort of work before and we did work out together exactly how he would do it and the systems to use, and that worked well. This was Ray and Tony of Unwin and Sons, 61 Brook Road, Essex and I have no complaints about them at all. They did a good job with no problems showing after 2 1/2 years, just what I asked for, with excellent subcontracting to a company doing the new ceiling mouldings. Very competent all round.
If you wish to consider balancing between different options (insulation types, thicknesses, positions and glazing systems etc.) I suggest you use a competent consultant like Parity Projects, who I know and they are excellent.
We certainly don’t notice the loss of internal space, and with the repositioned radiators and loss of water storage tanks and removing of one fitted cupboard, I guess this makes up for it. We have also changed some of our furniture for smaller stuff but we moved from a larger flat in Brussels. Some electric sockets were moved to the new walls, no problem.
Some people think breathable insulation is best but I prefer installing a good vapour barrier with internal insulation to stop the moisture tracking across to the original wall in the first place. Condensation is a much discussed and not necessarily understood subject. But we know of no interstitial condensation problems if internal insulation work is properly carried out and in some instances measurement of damp in timber beam ends with internal insulation installed, show reduced moisture content over time. Research and monitoring is ongoing. I think wall dampness is often associated with rising damp and penetration from outside, and often this is kept in balance by subsequent drying off to the outside.
We don’t live a very consistent life and the flat was rented out before we moved back, so there is no direct comparison. Our average annual gas consumption over the past 2 years is under 3000kWh, i.e. not much (includes cooking). As the flat always feels so warm, cools down slowly and heats up quickly I am sure the energy improvements are working very well. The new comfort level is wonderful! The double and secondary glazing also makes the flat much quieter and we are close to busy roads.
Rather than “passive” are you thinking of “zero energy”? We have passive ventilation and some solar gain in our flat, and there is a lot of thermal mass internally with the brick internal walls (all normally seen as passive features). As to zero carbon dwellings (like PassivHaus standards plus) using very high insulation levels, mechanical ventilation with heat recovery, and solar thermal and PV, they can be expensive, although a very satisfying concept. I believe that it is more important to treat all you can to a very good level (e.g. high insulation, double glazing with low e and argon fill, condensing boiler with top controls, draught proofing, low energy lights and appliances) and not necessarily go for broke! New housing may be a bit different as it is generally cheaper than refurbishment to go all the way.
My roof over hung the wall by about 300mm so losing 100mm was not an a issue.
I have gone below ground level at the walls with the insulation to insulate as much as possible. As I have a concrete floor this will prevent any cold bridging.
No I did not move any windows. I have extended the windows sills and made them slope so water runs off off them. There are no shading issues at all with 100mm insulation on the outside.
My existing windows remain in the same position, as they are upvc they had a substantial frame. I have insulated the reveals with thinner insulation of 40mm depth.
Not at all. I still love it and it works perfectly.
No, we didn’t strip the pebble. We removed the loose stuff and repaired any gaps where render was cracking/falling off.
Because the pebble wasn’t thick and had been painted it presented a flat enough contact surface for attaching the polystyrene.
Had it been just original pebble, particularly of the thicker variety, we’d have either first rendered it or stripped it back to the brick if the condition was poor. If you do render pebble dash you must be sure it’s 100% dried before you insulate using polystyrene.
Actually I used Enviroglass paving only for the garden patio. I used regular floor tiles in the kitchen. However there are lots of recycled glass floor tiles available, just google that and you’ll find several manufacturers. I don’t know anyone who has used them with underfloor heating. Perhaps worth chatting to some of the manufacturers and maybe getting them to send you a sample which you can test out on a radiator?
Aerogel works but it’s expensive, so you’d only use it if you really have to. And if you have timber suspended floors, you probably don’t have to.
The only reason I couldn’t use a more conventional approach someone had unhelpfully filled in my void with concrete. So I had to insulate on top of the floor boards, and then I was forced to pick a thin insulation material as I didn’t want to lose head height. If you’re in the same boat, then definitely consider aerogel. I bought Spacetherm from the Proctor Group; they even sell this on eBay. The one I got was bonded on to chipboard so that it’s easier to handle and fix things to. You can phone them up and ask for a quote for that.
However even better than aerogel (but at the time not easy to buy), are Vacuum Insulated Panels. They’re a better insulator than aerogel but you mustn’t puncture the panels otherwise you lose the vacuum. So usually you place them underneath the floorboards. They come in standard sizes and you can fill in the gaps with aerogel.
We installed our Slimlite double glazing in 2009, after much research and debate. They are on the front façade only, six over six Georgian style, and had to satisfy Conservation Area scrutiny from the planners – ie. no change in appearance from the front street. We tried to use the existing sash frames but our builder found they were not reusable – they were poor quality replacements of the originals anyway. Replacing the whole sash enabled us to get a much better overall result in terms of insulating the sash box and aligning it with the internal wall insulation to avoid cold bridging. Equally critical, we achieved air tightness with double seals on each sash (ie. inside and outside).
At the time we were making the decision, doubts were raised as to the long term argon gas retention capabilities of the Slimlite glazing units. Slimlite did not yet have the appropriate certification in relation to this aspect of their product although they believed that a loss of 1% per annum is likely. Their units had a guarantee for 5 years at that time, although some time before that their guarantee was 1 year only.
We went ahead realising the risk would be that at some point in the future we may need to replace all or some of the glazed units. That might be with Slimlite again, a future higher performing version of the Slimlite or another type of glass such the evacuated type. So far, no failures, but we’re only at about the 4 year mark. I wonder if their guarantee remains at 5 years? And I have a gut feeling that smaller Georgian style panes might be less prone to failure, but that might just be optimism.
We refurbished in 2010. It took 10 months from January to October.
We had a highly trained engineer. To do it properly, some real expertise and attention to detail is required.
The standard was excellent, but the builder and I fell out over various non-technical matters, primarily because we had hoped to go into business together and as sometimes happens this led to differences of opinion.
You can read the FAQ here I wrote on How to take a green retrofit to Passivhaus standard. There is lots of other information – including a very in-depth video log here and a detailed case study here.
I insulated the solid walls internally using Sempatap which is only 10mm thick but quite effective.
I have fitted Sempatap in 2 houses and not had any issues. I admit I have not peeled it off to look at what may or may not be happening behind the Sempatap in areas where the seal may be less than 100%. But there is no visible damp or mould.
In terms of performance, my experience is that the rooms after the Sempatap was fitted were significantly warmer than before on a like for like basis.
3. Sempatap is thinner and hence less obtrusive. I aim to fit more insulation on top off the Sempatap in areas where it is practical and inobtrusive.
Overall I am very happy with the Sempatap. It would be interesting to see the origin of many of the anti-Sempatap stories. My feeling is it it is a bit like 80% of objections to wind farms can be traced back to fossil fuel /nucleur lobbyists.
I put the insulation between the joists in the original suspended wooden floor and kept it in place with chicken wire stappled to the underside of the joists. All this work was done from below the floor without lifting the floor boards as there is sufficient crawl space. Best to work with someone else for this as avoids climbing in and out all the time. Wool (being flexible, is good for this as the joist are not parellel (variable spacing).
I made a trap door through the existing floorboards to give me access. As the area under the floor is reasonably deep I did the underfloor insulation with sheeps wool by crawling underneath the floor without taking up the floor boards. Less disruption but you need to be slim and not mind confined spaces! You might also encounter some builder’s rubble en route. The underfloor can also provide good storage once cleared.
Where I have used Thermafleece for wall insulation I have also used a thick polythene vapour barrier. This needs to go on the internal face of the insulation and be 100% (be careful at edges and around sockets etc).
Wool is a hydroscopic product and so absorbs moisture without affecting its thermal properties which is not the case for other materials such as Rockwool. The wool can also be handled without a mask and gloves and is a good use of a waste product. Use dress maker scissors to cut it to size.
There are now other similar wool insulation products such as Black Mountain which you may find to be cheaper.
I did not use a vapour barrier for the underfloor insulation with Thernafleece. This has not been a problem for me.
I have fixed Magneglaze secondary glazing over the sashes. I draft proofed the sashes where possible. We also refurbished the sash windows (new cords etc) and returned them to the natural wood on the internal faces. Cheaper than new windows and nicer looking.
I insulated the solid walls internally using Sempatap. As this is only 10mm thick I avoided having to adjust the window frames, dado rail etc. And it doesn’t matter whether you do windows or walls first.