Mike

Because if you run MVHR flat out the noise can be intrusive. Ideally run it at no more than 2/3 capacity, but maximum ¾ capacity. Preferably choose units from the Passivhaus database, which lists units have been independently tested to into account both the heat recovery rate (for which the standard way of measuring it is inadequate) and the electrical consumption of the fans (which will be running 24/7 for many years). Efficiency Ratio = overall performance (heat recovery & electrical consumption).

Something may have changed in the meantime, but Ofgem concluded the opposite back in 1999: "Another result from the modelling was the observation by participants that gaming - seeking to exercise market power - was perceived to be easier under SMP pricing rules than pay-as-bid" "Under a pay-as-bid system, buyers have to go out and find the best deal available, which will increase the competitive pressures on generators" "These points are supported by the business simulation modelling that has been conducted by the RETA Programme, where prices under SMP came out higher than pay as bid" The New Electricity Trading Arrangements, Ofgem/DTI Conclusions Document, October 1999, page 91 (SMP = System Marginal Price) Not sure what subsequently happened that flipped the position in favour of marginal pricing. It would be interesting to know.

Was pretty much ruled out. All mandatory options have now been ruled out, not just pay-as-bid. Decisive Government in action / Decisive Government inaction. What you think the market will bear (for each half hour slot), knowing that if you bid too high, you'll get nothing.

Not Roger, but pay-as-bid is one leading proposal. In other words, if providers A, B and C offer their electricity at £60, £80, and £200 per MWh then, if they are chosen, pay them £60, £80, and £200, rather than paying all of them £200.

Having once worked in a hotel that experienced at least one connector failing every month - but sometimes every week or more than once on the same day - I can confirm that this is a problem. Twisting them during installation is a known issue, but they do have a limited life even when correctly installed. I tolerate them in a cistern, but have returned to using regular copper pipe elsewhere. Replacement every 10 years is advised if they've been installed. Only buy ones that are made to the relevant European / British Standard (sorry - I can't spot the number right now). The standard isn't very good, but it's better than pot luck.

It's not yet painful enough. The 70's Oil Crisis was painful and did, briefly, prompt Government action in the UK, even if it didn't turn out well - another expansion of nuclear followed by dependence on gas...

Yes, very useful. It's one thing that I wish we had here in France - instead we use regular sockets on a lighting circuit (2 maximum, unless a contactor or the like is used) & rely on intuition to distinguish them :(

Evidently not an original idea, but build to the Passivhaus standard (or close to it as feasible) and minimise the need for high-tech solutions. Though I'd now evaluate summer overheating against forecast climate data for the 2070s, now that it's available in granular detail for the UK. As for long term maintenance costs & durability, the 25-year evaluation of the original Darmstadt passive houses (occupied since October 1991), available here, is interesting. TLDR: Heating requirement: average for the 4 homes remains stable at 8.4 kWh/m²/year (compared to the 2016 German average of 138 kWh/m²/year) Glazing: gas losses from the triple low-e glazing units so low that these can be used for at least two additional decades Airtightness: after replacing the seals of the opening lights, airtightness returned to the as-built value (0.21, from 0.26 pre-replacement) MVHR: no significant contamination despite never having been cleaned, expected to last >50 years apart from filter changes and fan replacement (1 of the 4 MVHR units had 2 fans replaced in 2002 for about €500; all others were still original)

You can probably add cooling to your heating system for much less than £7K, or to add it later, if you design it in now. In the meantime, MVHR is essential. Then change the design and avoid the problem. Upgrade your roof insulation using a product with greater decrement delay, add a brise soleil to the window, etc.

In terms of insulation they're certainly viable - there are 42 Passive House buildings using Porotherm in the PassiveHaus database, 13 of them certified. The PH database includes 1,784 new-build masonry buildings in total and - since cavity walls are unknown in most of Europe and there are only 83 UK buildings in the database - the vast majority will be solid wall construction + insulation of various types; you can view a summary of what was used.

Yes, for concrete blocks.

I'd guess that they've run round plastic conduit with 90° bends, either in the cavity, or chased into the cavity face of the brick. They may have used singles (single wires, rather than twin-and-earth cable) to make it easier to pull the wires through. If you look at the photos, they've only done this in a few places, not throughout, which would make it less of a pain.

Kaiweets KT360B. Get a spare battery with it - they do last a long time, but it's inconvenient if your forget to recharge it. If you'll need a plasterboard lifter, use that instead of buying a pole (except in small spaces). Fix a Huepar fine-tuning mounting bracket to it with the magnet.

+1

A lot depends on how you plan to get the work done. If you want a single contractor to do everything (or everything up to a defined point - e.g. leaving you decorating), then having a good local QS on board to run a tender (and to oversee the ongoing contract financially) is often a good move. If you plan to split the work into different elements that you (or your site manager) will be coordinating, then you may well be dealing with smaller contractors who may not be used to pricing work that way. See my comments here (and the thread in general) for more.