JohnMo

Is a step an option? With that little insulation in the floor, you should really reconsider if UFH is the right thing to do for that room. The downwards heat loss will be big. Your downwards heat loss, will be the delta of the water flow temperature (could be around 35 to 40 degrees and the ground temperature, around 7 degrees, multiplied by the u value and area. Superfoil requires an air space either side of it to get advertised performance. So don't go there. Your need to use PIR or better still PUR.

Practical experience of two systems. Commissioning easy as a single system, as long as each unit is balance, same going in as going out and the system as a whole as a whole has the same coming in as going out. The air doesn't care which unit it is extracted by. No fighting experience at time with the two systems. Reliability, we had an issue with one unit that required a new fan motor. The other ran and provided enough ventilation for the house. Two sets of filters required, an additional ongoing to expense. Electric costs same or lower, as you can position the units to reduce duct lengths and have a lower system pressure, the fans run lower on their performance curve so use less electric. Boost, generally only our small unit is on boost from showers etc. The large unit is rarely in boost. Reducing ventilation heat loss. A single unit would boost the whole house ventilation.

The issue with spray foam, is when it's applied to roof in the incorrect manner. Ie normal cold roof space, then spraying in the back of the roof tiles, closing all the required ventilation. Mine was applied by a recognised builder. But what ever system you go for, you need to an interstitial condensation analysis.

You are correct Scottish building regs actually say 8000mm2, so a 760mm door would require 10.5mm, an 838mm door would need 9.5mm and English regs would require 10 or 9mm.

Mine is as follows Pitched roof Slate Breather membrane 22mm Sarking boards 256mm posi rafters - under drawn with 100mm battening, full filled with spray foam. VCL airtighness layer, double side tape and stapled to battens, fully taped and glued to wall 50mm service battens Plasterboard 12 degree roof Same except, mechanically fixed EPMD membrane with fleece below, breather membrane and 18mm plywood - everything else as above.

UK rule G98/99 etc, expressly forbid a grid connected inverter from operating in Island mode. Type approval testing ensures manufactures comply. I tested mine (Growatt) with a generator and house disconnected from grid and even with generator running (correct volts/hertz) the PV supplied no power to the house.

Building standards require a 10mm undercut above floor coverings, to allow all doors to be closed and get the required air movement around the house. Generally you only extract from wet rooms and kitchens. Supply goes to all dry rooms. In a dry room air enters the room away from a door or opening window, flow across the room out/under the door either to an adjacent wet room or down the corridor to a wet room. This way all the air in the property is replaced. Having a supply and extract in the same room, means the air flow path misses most the house just goes direct from A to B. Below is a guide to air flow rates by different countries in the UK and passivhaus

Our direct air connection was a pain to get to, to correctly tighten the hose clips, so the installer did his best efforts without strip down if the stove. He tried to bodge and hope no one was watching or checking. That is sometimes the issue, the installer takes shortcuts. I didn't accept the short cut and the fitter had to take some of the stove apart to fit the hose clips correctly, took about 20mins to do the job right. Our building air test had no leaks at the stove or the outside air connection.

Not sure you need to double any flow rates. Ours is set at normal flow 45m3/h and a 25% uplift in flow rate when asked to boost.

I would go into the link Nick gave you. You need to know your floor area and perimeter and floor buildup. Then just play with the calculation

I would just install a manual MVHR boost switch near the hob. We don't use the cooker hood that much, unless doing smelly stuff. Then as above recirculation, carbon and grease filter.

The other thing to add is the building airtightness. An airtight building needs an external air feed, as the stove has to pull air from somewhere. If you have a tight house ie using MVHR you need this external air to get the correct flue draw, otherwise you will have difficulty lighting the fire and lots of smoke entering the room when you open the door. Things that concern me about the direct air: 1. A draught from the stove when not in use - no as ProDave explained 2. Drilling a hole in the external wall for not much of an additional benefit - see answer to 1. 3. The “room - sealed” stove being leaky so when the stove is off it makes the room colder. If it's leaky you have more to worry about, the carbon monoxide leaking out when lit will kill you Things that concern me not getting the direct air: 1. Enough draw to fuel the stove (this should be fine i would imagine), see what I said about airtight house 2. A cold draught pulling across the room from other sources to fuel the fire find and download manufacturer install manual and read it.

That reminded me to submit a meter reading, when I tried the app said my smart meter was working and I couldn't submit. Over two years after it was first installed! British Gas (electric supplier) had not completely finished the commissioning in the house, so rang this afternoon to get an appointment - the engineer will be with me tomorrow at 8am. Make wonder what the meter team are doing, to get an appointment that quickly.

No. Just divide the thickness (in metres) by thermal resistance. Then you will have the R value, to get the U you need the inverse, so 1/R equals U. 0.022 is PIR thermal resistance 125mm thick. 0.125 / 0.022 = 5.68 1/5.68=0.17=U value.

Even electric vehicles have a bog standard battery to drive the 12v stuff. Leisure board, caravans etc are ok with big lead based batteries, no real justification to have a light energy dense battery, that isn't normally managed well and is cheap enough to replace every few years. So normal batteries will be around for decades.

I saw it also on the STV news, a few weeks ago. We are in NE Scotland and our two neighbors are are doing a new build and will be asking for meters this week, will be interesting to see how they get on.

Just order a year's supply of muck muchers. My soil stack is about 50m away from the treatment plant at the end of the house (single storey) and only about 3m in the air. If the wind is blowing in the wrong direction it can be a bit smelly. Worth a go for £39 delivered.

Just a single storey

Thought the window over hangs would be enough, but unfortunately the sun gets in late afternoon to early evening.

We have a larger and smaller one. 193m2 and tall ceilings. One unit does the two guest bedrooms, and bedroom two en-suite and our bedroom en-suite. We shower in our en-suite, so only the small unit goes into boost, instead of the whole house. The other unit serves the rest of the house. Small reduction in electric, but less air changes in the winter, which should mean slightly less ventilation heat loss. Running cost for electricity should be pretty much the same for one big one or two smaller ones as the total flow rate is the same. They could be slightly lower with 2, as your duct runs should be shorter, so less resistance to flow and fan runs lower on its curve requiring less less power to the fans. Filters X2 costs.

Good suggestion, but there's a 45 degree slope down (down 8m) about 4m in front of the house, then a road then a loch. So not much option for trees unfortunately.

We have big overhangs over the windows which is great until mid afternoon and the the lower sun going down to west get in. The internal blinds work quite well, but not good enough. Will have a look at external blinds also, thanks

Or a dMEV fan, designed to run 24/7 at very low watt draw, so running costs should be low. Shop around and they can be picked up cheaply enough, greenwood, vent axia etc.

Think I would have shrunk some of the south/west facing windows, trouble is we have great views, seemed a shame to miss out on them.

Been told we need cooling in the lounge and possibly in the bedroom (about 10m away from lounge) for next year. So looking for advise So two options, as I see it. May be others? 1. Get a heat pump with cooling, run through the UFH, most expensive option. Not sure how good it is compared to aircon 2. A2A, least expensive option, but depending on how many units I need could be more expensive. Could run in heating mode also if required. Not sure how to size? Not keen on pulling house apart to fit something and wife not keen on external units (but may have to live with one) Have seen through wall aircon, but input vs output doesn't appear that good. Water cooled aircon, main water in and then to drain, seems a waste of water.