Energy consumption

Over the past couple of weeks I’ve been trying to measure the heat input to the house from the heating system, and gain a better understanding of the way the house responds to changes in temperature.  I already knew that the air source heat pump (ASHP) only seemed to come on for a couple of hours or so each morning, and also knew (from power measurements on the supply to the ASHP) that it rarely seemed to use more than around 800 W to 900 W, settling down after about 10 minutes or so of running to around 400 W to 500 W.   What I wanted to find out was how much heat was actually being supplied to the house from the underfloor heating (UFH). Continue reading “Energy consumption”

Domestic electrical installation earthing and circuit protection – part 2

In part 1, I left the tale at the point where the DNO had provided a supply to the premises, most probably with a TN-C-S earthing scheme for a new build.  For the purposes of this article, I’ll assume you have been provided with a supply capable of running a TN-C-S earthing scheme, and that the incoming supply looks something like the diagram below, once the house is completed: Continue reading “Domestic electrical installation earthing and circuit protection – part 2”

Downloads from the top menu

Some have asked me for copies of stuff, or links to downloads, and rather than email them out individually I’ve added them to the “downloads” menu at the top of the home page here.

The link to the Stroma FSAP download page is just that, a link.  Stroma offer their SAP software on a free basis, so anyone can use it to do their SAP calculations.  However, only an accredited assessor is allowed to officially submit the reports, so although useful from an educational perspective you have to be aware that the reports that are produced from this free software will be watermarked “DRAFT”*** and will not have an assessors name or registration number on.

The spreadsheets were all written by me to help me get my head around some of the things when I was first designing our house, to allow some “quick and dirty” comparisons of different build methods and also to assist when it came to doing the VAT return at the end (HMRC will accept these printed form replicas without any problem at all, BTW). Continue reading “Downloads from the top menu”

Domestic electrical installation earthing and circuit protection – part 1

This is a, rather lengthy (even though it was intended to be brief), bit on the history and background of domestic electricity supply earthing and circuit protection systems, and why they are important, to help understand why we have earthing and circuit protection schemes in the first place, what they are for, how they’ve evolved, and why, together with the expertise of the electricians we employed, I made the choices I did.

Like any history, it’s written from my personal perspective and reflects my view on why certain things were done at certain times.  Much of the reasoning for some of the decision making has been lost, so inevitably some of the historical aspects are a reasonable guess. using information from multiple sources.  The later history is more accurate, as I was indirectly involved with rule making from around the time of harmonisation onwards, specifically with the formulation and application of the LV Directive and the EMC Directive.

This may sound an odd thing to write, but there is NO such thing as a safe electrical installation, and there never can be.  Safety is not a finite entity; no matter how hard we try we cannot remove all of the risk, and some risk ALWAYS remains.  All we can ever do is try to mitigate the remaining risks by a carefully thought-through design, balancing what we personally find acceptable in terms of risk, cost and convenience, with what is within the requirements of the regulations that apply at the time your installation is installed. Continue reading “Domestic electrical installation earthing and circuit protection – part 1”


It seems this blog has caught the attention of the spam bots and now gets hit with around 20 to 50 comments a day, 90% of them from the same scammers trying to con people out of money for writing articles (and as some will know, I’ve written a few articles, had them published and know a bit about how the “writing for (very little) money” game works).

The worst scammer of all is an outfit called “writing job income” (and, no, I’m not going to be  daft enough to post their URL; it ends in .com and isn’t hard to guess, and I suggest no one looks it up and visits it, unless they really want to be scammed).

So, I’ve installed some stuff to try and reduce the amount of spam here, but it will only really work well against the spam bots.  Right now I’m reluctant to add the “prove you’re a human” stuff before people can comment, as I don’t like it and I suspect others don’t either.  However, if you get a pop-up when you’re trying to comment, then it means the system here suspects you’ve not read the post before writing a comment.

Hopefully this may reduce the amount of garbage I get in my inbox every morning, although I doubt it’ll stop those who are STILL being a bit childish and sending me junk out of personal spite – I do know who you are, you know, as some of you aren’t bright enough to cover up the trail you leave behind…………………..


Part Forty Six – Over-thinking things – Part Two

When going through the list of things that we hadn’t used consultants, specialists, etc for, I realised I’d forgotten about a few.  Well, it’s fair to say that I hadn’t really forgotten about them, but had forced common sense (an increasingly rare commodity) to dominate.

I’ll give just one example, but I’m sure others will have many more (especially when it comes to ecology, archaeology and wildlife!).   I had a rough idea of the ground we would be building on, as we HAD to have a hydrogeological survey for the borehole (no easy way out of that one, if you want a quote from driller).  The survey wasn’t expensive, and I could have obtained almost all I needed from the BGS website, plus a look at a lot of the local borehole drilling records, that shown the type of sub-strata and depth.

So, I knew that we were on the exposed top surface of blue gault clay, and that it was at least 3m, perhaps closer to 4m, above the water table.  I also knew that the gault was highly compressed here, so was almost a semi-hard mudstone.  The first thing I was asked by the foundation design structural engineer was the bearing strength of the sub-soil and whether or not the clay was subject to movement with varying water content (heave). Continue reading “Part Forty Six – Over-thinking things – Part Two”

Part Forty Five – Architects and consultants, what are they likely to cost, and can you save money by doing some of this yourself?

First a bit of clarification.  Some have expressed a view elsewhere that this blog is in some way a revenue-generating device for me.  I can absolutely assure anyone reading it that it is the opposite.   It costs me money to pay for the web space, and I don’t gain any revenue from it at all.  I won’t  allow advertising here, and spend a fair bit of time deleting literally hundreds of spam comments, to keep it free of commercial influence, as far as is practicable.  As a consequence, whatever you read here is my personal view, and not coloured by any commercial influence.   My only intention here is to hopefully try and help others, who may learn from our experience.  If it saves them money, or eases their task, that that is all the reward I want.

I’ve been prompted by a discussion, following a couple of free podcast interviews I gave for House Planning Help:


and here:

to have a think about what “self-build” really means and how much money you are likely to pay out to others, even if you were to do all of the building work yourself. Continue reading “Part Forty Five – Architects and consultants, what are they likely to cost, and can you save money by doing some of this yourself?”

Part Forty Four – Over-thinking things – Part One

From the very start of this project I have now realised that I have wasted hundreds of hours thinking far too much about things that really don’t need worrying about.  In this episode, I’m going to try and focus on a few of them, I’ve no doubt more will come up in later posts.


I mentioned in a reply to Mike in the previous part that I had wasted a lot of time doing things that I thought would be needed for the building control completion inspection, but that it turns out weren’t.  The same is true about so much of this build, that I think it’s well worth trying to summarise some of them in a single post.

Firstly, I should point out that as a retired scientist I find it far, far too easy to get sucked in to investigating details and finding out why things behave as they do.  Sometimes this is a good thing, but 90% of the time it leads to a great deal of wasted effort.  The classic is the initial house design.  I was obsessed with how to heat it and making sure it had enough passive solar gain in winter.  It didn’t even cross my mind that it might  need cooling, neither did it cross my mind during the design stage that having a house deep into a cut out into a south-facing hillside, near the bottom of a fairly sheltered valley, would mean that the micro-climate around the house was significantly warmer than the average for our area, which is on the edge of Salisbury Plain – a notoriously cool place! Continue reading “Part Forty Four – Over-thinking things – Part One”

Part Forty Three – Completion! (and getting the VAT back……………..)

After much faffing around with details and paperwork, we finally have a Completion Certificate!


Getting things ready for the final Building Control inspection turned out to be an exercise in doing loads of work that wasn’t actually needed.  Very frustrating, but a consequence of me not having been through the process before, and assuming that Building Control would want more evidence of compliance with the regs than they actually did.

I had prepared copies of things like the water usage calculations with evidence of measured flow rates from all outlets, and none of that was needed, for example.  I’d also prepared reasons justifying the three pressurised systems we have, and why they did not need sign off against Part G by a competent person, and again none of that was needed. Continue reading “Part Forty Three – Completion! (and getting the VAT back……………..)”

Part Forty Two – Water Treatment

This blog entry is just looking in detail at the ozone treatment part of our borehole water system.

Our borehole water has a high concentration of ferrous iron, this is what’s often called “clear iron” as it doesn’t colour the water.  It’s fairly common in water drawn from deeper aquifers, particularly in areas where there are natural iron deposits or soft (often slightly acidic) water that dissolves iron (and other metals, like manganese) from the surrounding rock.  In our case our water comes from the Lower Greensand formation, an aquifer that is known to have water with high concentrations of ferrous iron as well as dissolved hydrogen sulphide gas (the “rotten eggs” smelly stuff).

The traditional way to remove ferrous iron, manganese and hydrogen sulphide from water is to just add oxygen to it, usually in the form of air, but it can be by using an oxidising catalyst.  The most common oxidising catalyst is manganese dioxide, used in a filtration bed.  This works OK, but it does eventually need replacing, or regenerating in some way, as it will lose its ability to oxidise after a time. Continue reading “Part Forty Two – Water Treatment”