Warm at last!

Mission accomplished: The Mur Crusto passive solar gain project is largely complete and we’re reaping the benefits immediately. We should have done it years ago. There’s more to do, of course, but now if you want, you can see all the best pictures of the construction from beginning to end. Click here to take you to my photo album where you can choose either to see all the captioned pictures as a slideshow in sequence, or move around the album of thumbnails to click any you're interested to see full-size.

Wonderful to be warm! The most obvious immediate benefit is that the core of the house, previously like a cold store even in summer, is now permanently warm. The temperature outside last night dropped to 3 degrees Celsius but we were perfectly warm in our living room, needing no additional heating. Remarkably, even late in the evening, the conservatory still felt quite warm. So we really are reaping our passive solar gains.

Battle against the weather: This summer has been lousy. A lot of it was dry but cold, but there have been long periods of 'unsettled' weather; Met Office parlance for rain and wind. Whilst there was no glazing, the concreted floor (see photos) repeatedly flooded and had to be pumped out. I developed a sort of 'cut and run' strategy for working, keeping all my tools in a wheelbarrow and coming out when the rain stopped. I'd work until the next rain and then trundle everything away into shelter. This is no way to work but I had no choice. Latterly, we did have a few weeks of dry weather which was perfectly timed for me to get on with glazing the roof and then the windows. Glazing the roof was what one might term 'a non-trivial operation'. (It said in the assembly instructions something like, "Now glaze the roof"!) Doing the lead flashings before that was also quite difficult, lead being heavy and difficult to fit in the continuous slot I'd cut in the wall of the house. But the roof glazing took the biscuit for difficulty: the glass units are heavy and locating them tricky. The seals for waterproofing are fiddly and messy (silicone all over the place). But I managed in about 2 weeks of struggling.

Last minute: The last pieces of glazing went in the east gable end a matter of 2 hours before the rain started again, just in time to stop the loss of warm air from inside the structure. From that time on, it's been a different world inside. Lots of light, warm space and the wonderful feeling of warmth flowing into the old, formerly cold, stone building -- all for free and without burning any fuel. There are a few small leaks which I have to sort out when the rain stops but otherwise, it's really great. Everyone should do this if they can. It really makes a difference!

The next stage: To gain the full advantage of this structure, I have to complete various things. One is the floor which I shall insulate. Another is the internal wall plastering and painting with a tinted paint ('sandstone' is the name of the tint). White houses are a serious mistake; very pretty but cold. It's just like the (vanishing) Arctic sea ice. Being white, both reflect almost all heat away. A dark wall or ice-free sea surface absorb most of the solar radiation and so heat up: good for warm housing; bad for warming oceans and accelerating ice melt. It's the albedo effect and it applies to houses just as it does to the Arctic Ocean. Ideally, I'd paint the internal wall black to absorb as much heat as possible and act as a massive heat store. But one has to compromise. A black house is not acceptable! So it's going to be that sandstone tint. Even so mild a colour makes a difference too. On a sunny day, place your hand on the white paint and it's cold. Place it on the sandstone paint and it's nice and warm.

Controlling the warmth: I also need to investigate simple control systems to duct heat actively into the house, using a fan, but only whilst there is heat to duct. In other words, I need to devise a simple system which switches on whilst it's hot in the conservatory and off when it's not. It would ideally recirculate the cooler air from the house into the conservatory for re-heating. What I don't want to do is dump heat into the atmosphere if it's needed in the house. If you, reader, have any ideas about how best to do this, please leave a comment below this post. I'm sure there are systems available so I don't have to re-invent the wheel.

Details of the building: For those interested, the U-value of the low-e double glazed units is 1.3 (Planitherm). The conservatory was manufactured by Portland Direct, the DIY branch of Amdega, all made from treated and painted softwood from (they claim) sustainably managed Scandinavian forests. This large structure cost around £10,000 delivered, with telephone back-up support available and very good. It's guaranteed for 15 years. The other bits and pieces (like blocks, cement, lead and so on) have probably cost another £1500 or so.

Then there's the small matter of my labour. I started excavations in January and completed the glazing in mid-September. I have probably spent one third of my available time working on this during that period, saving 4 weeks away in Scotland. Val has helped when needed, particularly with laying concrete and holding things in position and I have employed Simon, a carpenter friend and one of our organic veg customers, for 4 days in total. That's about it. Hard work, definitely a 'non-trivial operation' but rewarding. Most reasonably fit (I'm aged 60) and reasonably competent people could do similar. Building is, in part, a question of thinking things through slowly and carefully before doing them and using ingenuity where possible to save time and trouble. So... go for it!

Going down; going up!

Passive solar project continues...

Going down: At last, the digging out and barrowing on tons of boulders, stones and earth are over. The deepest part of all was the foundation for the 'dwarf' wall which will support the conservatory structure. Here (right), Val is checking the base level of the foundation trench with the water level (see previous post). Fortunately, because the ground is so hard and stony - thanks to glaciers 14,000 years ago - foundations can be minimal.


Going up: From this point on, it's up! First the foundations, then the base part of the dwarf wall which I've arranged so that the top of the blocks is exactly the same height as the finished floor level inside the structure. At least I hope I have. Val and I have treble checked levels, measurements and angles, all of which are made more complex by the front wall of the old farmhouse (to which the conservatory will attach) along which nothing is true; neither vertical nor plane.



Attention to insulation: The picture (above left) shows me, on a hot day wearing my sombrero, setting out the first double line of blocks. I'm using a sheet of Ecotherm insulation to ensure that the wall cavity is wide enough to hold these sheets when I build the rest of it. I intend to have 50mm of this high-quality insulation within the wall cavity and another 50mm attached to the inside and covered finally with plasterboard. I've found from my experience of building our holiday eco-cottage that insulation pays massive dividends. I shall also be insulating the floor. On the right (above), I'm pouring what seemed to be the thousandth barrowload of concrete - it's hard work! - to form the floor slab, 100mm thick. Underneath it is the black polythene damp proof membrane which we've lapped up the wall of the old house (which has neither foundations nor damp proof course) and over the first block of the dwarf wall. The damp course must always be above final outside ground level, of course.


Sub-floor complete! I finished pouring the final load of concrete just the day before it started to rain, the first rain for about 5 weeks. I'd worked 5 days previously, about 3-4 hours each day, making concrete, barrowing it and pouring it into 'cells' formed by pieces of timber. The top of each timber Val and I had carefully levelled (water level again) to ensure that the top of the levelled and tamped concrete would be about 100mm below the finished floor level. This leaves room for the underfloor insulation. As I write now, the concrete slab is flooded with water from all the lovely rain.


The next step: The conservatory frame arrives on a lorry in 3 days, complete with all the double glazed low-e glass ready to be installed when the frame is up. When the rain stops, I'll get on with building the rest of the dwarf wall at which point the excitement starts: will the frame fit? are my measurements correct? how long will it take? Already, the pressure's on... we've got our table and chairs on the new concrete floor (photo 3 behind) and look forward to having the finished structure which, we hope, will solve many of our old house's heating and insulation problems. We are, in short, fed up of living in a permanently frigid house. (It's frigid because there's no proper insulation and we refuse to run oil-fired heating except for an hour or so in the early morning.) The conservatory will help immensely because I intend to arrange for surplus heat to be ducted into the old house, effectively using the walls as a heat store. How effective this will be we can't be sure but it certainly will be better than the way things are now!

The Grand Conservatory Project: space heating from the sun

Completed clawdd (Welsh word meaning earth-cored) wall end in the garden and the start of the excavation

Construction - mostly destruction at this stage - is underway. I've been nipping out for a few hours most days when the gales and heavy rain stop to remove a rockery and completely rebuild a clawdd wall. This is to make space for The Conservatory which, we hope, will result in a much warmer house, partly because of its insulating properties on the solid stone wall of the exposed front of the house and partly because I intend to duct heat captured inside the conservatory into the usually-cold inside of this traditional farmhouse. I hope the walls will act as a heat store. That's the idea anyway. Any ideas for simple control devices and fans welcome! (Please add a Comment.)

Now that the rockery and wall are 'rearranged', there's a lot of heavy work ahead shifting barrowloads of soil and rocks. I've tried to arrange things so that I don't have to move stuff twice. So the biggest boulders - some of which I could only just manage to slide or roll - will form the basis of a new rockery in the middle of the garden, burying the existing ugly concrete path which with dozens of barrowloads of soil. So most of the excavated materials aren't 'waste'; they're useful in a new and more attractive context: a rockery in the middle of a single lawn no longer bisected by the ugly path to the gate which was never used anyway.

The indespensible water level, one end attached to the building, the other being free to check excavation depth

Now that I have the detailed drawings of this conservatory from its manufacturer, Val and I set up a datum level which is based on the distance between the base of the upstairs windowsill and the top of the conservatory 'wall plate': the highest timber of the frame which is bolted to the building. I have to leave space below the sill for flashing to go in or it will leak. That done, we checked with a water level that both sills were the same height (they weren't) and measured down to a point which is 1 metre above the finished floor level, marking this with a line. I then attached one end of water level to the wall. This means I can attach the other end of the level to a measuring post whose length below the level is at precisely the depth below the finished floor level that I need to excavate. That is 1.2 metres for the path which I will make along the front of the new structure, allowing for a dampproof course to be made at floor level in the dwarf wall which I will build to support the conservatory frame and glass. The glazing, by the way, will be low-e glass, double glazed, with a U value of about 1.3. Pretty good.

Excavating is the way it's going to be for a few more days if the long-awaited colder, drier weather persists. Then the fun starts! I have to break up the existing concrete 'patio' where the conservatory structure is to be built. This is a hodge-podge of patches of different concrete and different levels and so, unfortunately, has to go. Will I do the breaking by hand (sledge hammer) or hire a hydraulic breaker? I think the latter! But do watch this space...