Stones

Small job to do, repairing a hole in plasterboard, the size of a 50p piece. @Crofter mentioned in one of his posts how easy he had found it repairing a skimmed plaster wall to a seamless finish, something he had never been able to achieve when repairing painted plasterboard because of the paper finish. And that's the issue I have, in a taped and filled rather than skimmed house (how I wish there were plasterers up here!) achieving a repair to plasterboard that doesn't stand out like a sore thumb is a challenge. Any suggestions from type make of filler, grit of sandpaper or any other trick or tip to get a finish that has the plasterboard paper like texture, which I would then paint?

@bikerchris I would second the suggestion of a Willis heater paired with a UFH circuit. Ideally you would run that to provide the basic background level of heating required (which, if well insulated, shouldn't be much given you are planning something smaller than a standard double garage). Incidental gains from human activity, lighting, PC's etc would do the rest. You could of course just opt for plug in heaters but I think the UFH would give you a much better level of 'comfort'. Are you planning a WC and need hot water?

We had Amtico in our last house (a large kitchen/dining/family room, flowing up a couple of steps into a utility) and were very impressed with it. Very hard wearing and the 'tile' we chose was very forgiving in terms of visual appearance - you didn't need to clean it constantly to keep it looking good. +1 to the comments about fitting.

Re the wall ties, our last house had a similar cavity due to the addition of an additional layer of insulation on the outer face of the timber frame. Helical screw wall ties were provided and used. Similar to these: https://www.helifix.co.uk/products/new-build-ties-fixings/timtie/

I'll third the use of wall boards vs tiles. 2 years on they look as good as new. Ours are fitted with a shower tray, the boards sealed as @ProDave describes. A doodle to keep clean, wouldn't ever consider tiles in a shower area again.

Yes, a certainty (or certainly what I have seen) within heated envelope. Using an individual Sunamp unit for each room starts to become a pretty expensive way of doing it. I know because I looked at having two separate Sunamp locations servicing different areas.

I made enquiries with Danwood, who although willing to build in my location, were somewhat inflexible on supplying a design that varied too far from their standard offerings.

I initially modelled our build using the heat/loss spreadsheet created by @JSHarris then added additional data - solar gain, incidental gains (basically household electricity use as most of it ends up as heat energy) and the impact of wind speed. To model solar gain I used data from the PVGIS website which has a handy calculator that lets you work out the project performance of PV systems. It also tells you the irradiation per square metre received by panels, so by setting the slope in the calculator to 90 degrees (i.e. vertical window) you can determine a per sq m figure for solar gain. You can also enter different orientations for the different elevations of your house. Once you have the per sq m figure, you can multiple against the sq m of glass (excluding frame) you have for a raw figure. In turn that has to be multiplied against the g value of the glass. I also factored in cleanliness of the glass. From that you can determine average daily, monthly and annual levels of solar gain. That's helpful in determining heating requirements but you need to know what the peak amount of daily solar gain is to ascertain cooling requirements. I found a site that provided that info and multiplied the average figure by the peak factor to get peak solar gain figures (roughly speaking the multiplication factor was around double in winter reducing to x 1.5 in summer). The end result was I could quantify in kWh how much solar gain there would be and how much I would have to mitigate to maintain my desired indoor temperature. Agree that designing in is the best solution, but as pointed out earlier, it really depends on the extent of the overheating issue. The longer the overheating season for your particular site / build, the larger the overhangs have to be.

Building relationships, it's what it's all about! ?

I've not had any issues at all in respect of our ASHP (either heating or DHW). We opted for a pre-plumbed package which meant on site, the plumber and electrician had simple connections to make (flow/return to ASHP, flow/return to UFH manifold, mains cold in, hot out, and electrically, power to ASHP, control cable between ASHP and control module on cylinder). The cost of getting a pre-plumb system was of course more than buying an ASHP, cylinder and all the various component parts, but there was a labour saving which I think pretty much balanced things out. Given that some of the problems we see described on the forum seem to be down to complicated installation issues, this may be something worth bearing in mind for future readers. It's probably also worth noting that not all of us are going to be able to achieve the type of heating performance detailed by some members, due to differences in design, orientations, microclimate and so forth. @Jude1234 Hopefully others more knowledgeable will be able to assist if you post some pics of your set up. Electricity consumption wise, it does seem a little high. Your ASHP will probably have some form of on board metering - any way you can check to see?

I looked very carefully at overheating but after working out the depth and angle of overhang required to eliminate overheating, realised it wasn't something I could easily achieve. On modelling the house by calculating what the average and maximum daily solar gain would be, I worked out that it was unlikely we would ever exceed 25C inside the house, and so it has proved. Overheating is of course a relative term, in passive house design, I believe 25C is the generally accepted level beyond which there would be a problem, although I would argue anything over 22 or 23C in summer starts getting uncomfortable. 25C is certainly too hot for me. As we fitted an ASHP and UFH I have the option of cooling the slab, but as yet have not used it for cooling, primarily because the hot spells don't last long where I live, and I'm prepared (or at least so far) to live with it for a few days. I looked into fitting a duct heater / cooler but concluded that it wouldn't be able to add anything meaningful in terms of heating or cooling due to flow rates (and limitations on the size/capacity of the heating / cooling duct units). I've also been in a house that had a Genvex unit fitted, and whilst pleasant standing underneath a supply air vent pumping out cooled air, the flow rates simply were not able to keep pace with the level of solar gain. As you've gleaned from reading the forum, others have a positive experience of using an ASHP to cool the slab, but this would probably be better described as a means of regulating the internal temperature of the house down to a more comfortable level. A cheap A2A unit, given you are going with gas, may well be the cheapest option of provided a reasonable air cooling capability.

We stick built one of our houses. Basically worked out roughly the same price as buying the kit once you factored in the cost of joiners making the frame up on site. If you are making the frame yourself (perfectly doable) then savings are to be had.

@DonGillies Welcome to the forum. Nice part of the world (I used to live a couple of miles from @pulhamdown ). Externally, your design bears a lot of similarity with the small development in Meikleour which was one I've always like the look of. Have you identified contractors for the work you won't be doing yourself?

Worth mentioning that savings are greater (effective cost of PV less) for more expensive roof coverings (slate etc) vs concrete tiles.

When I was looking at stairs, cut stringers added near enough £1K to the price. Are they a must have?

Yes, seen this condition numerous times. Generally speaking, fitting an ASHP was the easy answer / accepted and approved by the planning authority.

Isn't the main problem peak demand? We have plenty of generation capacity for large parts of the day, but work on fairly slim margins at peak times. Smoothing out those peaks would go a long way to helping I think. Reducing demand (which is what they want to do with 'smart' pricing) is one way, but I can't see massive reductions being achievable. Home storage capacity may well be (part of) the answer - instead of spending billions building a plant to meet peak demand, use the money to fit local storage that can be charged up from excess generation capacity outwith peak. I would also suggest the world needs to consider whether crypto currency mining, and powering the server centres that allow on demand streaming really are sensible uses of energy.

Likewise, I'm another former Scotframe customer. AFAIK, they only supply kits, albeit they will for a fee, take your project through planning and building warrant. It'll be up to you to find a contractor(s) to do the work, although the Dundee office may well be able to give you some recommendations. Can give you details of the builders we used (albeit several years ago) in Perthshire.

Not within the unit itself. It was the box on top of the lid / next to it I didn't want.

@Barryscotland Welcome to the UK's premier self build and renovation forum! What part of Scotland are you building in?

We have a Biopure fitted. Much of a muchness in terms of performance to the others listed. I was somewhat restricted in what I could get delivered to my location. Having seen @ProDave installation, it has the added benefit of a separate emptying point, i.e. you do not have to take off the main lid / remove the air blower to empty it, which you do with the Biopure (if you choose to house the air blower in the unit rather than remotely). I didn't want to have to remotely house the air blower which ruled out the Vortex, although on the plus size it does have a built in sample point and a system for adjusting the amount of air going into the unit.

This is something I've been mulling over as I have land available. Assuming you have a reasonable market, and the return on investment is acceptable, I think they key question you have to ask yourself is whether you wish (now or in retirement) to be tied to having to manage and service such a business. Of the various locals I've spoken to who run their own holiday businesses, maintaining high standards is probably the most important thing, which for the most part means rolling your sleeves up and getting the scrubbing brush out. You could of course opt to get someone in to clean and do changeovers, but would they really do as good a job as you / to the standard you want. I'm not convinced (and judging from various places we've stayed in) that paying someone (unless you pay them an awful lot) to do the changeovers and cleaning will result in the high standards you aspire to. The other thing to consider is, again, in retirement, do you want to be tied to doing say two changeovers and scrub outs per week, not being able to holiday etc. A small part time job may well produce sufficient income, perhaps have more flexibility (depending on the job) and not tie up your capital.

Can you quantify in kWh what you use / export from PV ?

@Nelliekins finding your blog very interesting (as another ICF builder). You've referenced on site training from the supplying ICF company. Can you quantify time wise how much training they provided, and can you give an indication of after support - could you pick up a phone and get help / advice etc?

When I've looked at E7 previously (and lived with it) I found you had to use 45% of your energy at E7 to make it worthwhile. A lot may well depend on the tariffs rate in your regional area. For us it remains marginal at best. Variable pricing (as and when it eventually comes in) may well be a better option as I would be able to time a lot of our energy use over cheaper rate periods, which I suspect would cover 10pm - 6am, and 10am to 4pm.