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We learnt how to keep our house cool this summer and thought we'd share what we've learnt in case its of use to others. We're in a timber frame building built to the Passivhaus standard but not certified. We don't have an ASHP, so no slab cooling for us but without a doubt our (not so secret) weapon are the external blinds. All our east and south facing windows (with the exception of 3 east facing windows - more on them later) have external blinds and as predicted by the PHPP these are the game changer. Our secret weapon is the little personal weather station (PWS) in the garden and with it's help this is how we've kept the house cool: In the evening when the outside temperature according to the PWS is below our target internal temperature of 21 degrees all doors and windows are opened and the MVHR ramped up. Overnight all the inward tilting windows are left open with the MVHR staying at a higher level and it stays like this until the PWS shows that the external temperature is rising towards our target 21 degrees - that happened at 07:50 this morning. As soon as the exterior temperature reaches our target then all doors and windows are closed and the MVHR is reduced to its lowest setting, we monitor the air quality with a couple of CO2 monitors as recommended by @Adrian Walker and increase the MVHR speed as required to keep good air quality. All sun facing windows have the blinds down, we have the mesh style blinds that don't block off the light but stop lots of UV. With this technique our hallway temperature has peaked in the early evening at around 21-22 degrees and the kitchen/dining room which has lots of east and south facing glazing has stayed below 24 degrees. As soon as we open up we get rid of most of that unwanted heat. The hallway starts in the mornings around 19-20 degrees. The reason I think the PWS is a secret weapon is as far as I'm concerned you need to accurately know the exterior temperature and when to let it in and when to keep it out. On a windy day, 26 degrees can feel cooler than 21 degrees but if you let that stuff in the house you're gonna regret it. If you don't have a PWS you'll probably be able to find one situated close to you on the Weather Underground website. Oh, and the 3 problem east facing windows without external blinds: 1 is the utility room. That has an internal blind and as it's the utility room the internal door to the rest of the house is kept closed. That room gets warm 25-27 degrees but the heat stays in that room which of course has an MVHR extract so the heat is slowly being pumped out of the house until it's door/window opening time then we throw the heat away with vigour. 2 is the ensuite which we deal with in exactly the same way as the utility. 3 is the main bedroom which has a great big window and curtains. The curtains remain closed while the sun is coming in that window but the doors are open so as that room warms up its heat is not being contained in that room. As the sun moves round and that window is no longer in direct sun the curtains are opened and a big old chunk of hot air falls out to be slowly extracted until window opening time. To me, its like the house taking a long overnight gulp of cold air and then holds its breath throughout the day until the temperature is 'just right' again.

One year on and the cats have adjusted fine thanks. A bit more info below in case anyone facing similar dilemma when a house move combined with immediate building start. They stayed in the run in the daytime (less stressful than being around all the demolition and early building work). After 6 weeks we took them round the plot on leads and by eight weeks they were settled to run free and now indifferent to any new tradesperson or power tool noise. No cat pictures but I thought it might be worth showing the cat run in case anyone else facing this - I built it in 900 x 1800 modules so when they were settled we moved it and clad in featheredge (leaving the chicken wire on) and added a pitched roof as an extra tool / material store and whilst garage demolished so we recycled the cat run too.

our house isn't finished yet and we have no ventilation apart from where I've yet to membrane and tape! but we're already seeing the benefits of our external blinds. earlier this week with all the blinds open it got to 31° while working on the FF. I went around and closed the blinds and angled them to allow light in but not sun left windows open over night and the next day we closed the windows and, even though some openings in the house were open as we were working and going in and out, that same room only got to 27°. once we can completely airtight the house and get the MVHR working I've no doubt that the external blinds will do a 'blinding' job of keeping temperatures down.

Agreed. However, I was thinking of using it to heat some water for a workshop sink using gravity. Just a small amount at a time for hand washing after working on the car.

Our secret weapon is a row of trees on the south of the plot. Conveniently they grow leaves in summer and shade most of the garden and a lot of the windows. In winter they fall off and let the sun into the house.

Thanks for posting this up. Interesting to see a company making a product that's not far removed from the DIY versions we've discussed on here. I've been thinking about what you could do with black PVC conduit, 90o elbows and solvent weld to make a serpentine flat panel absorber.

I pilot driled all the ways through. Then stitch drilled from both sides and chiseled out to finish. didn't have a 200mm core and love suffering. It was a PITA. all done pre plastering. Made the hole good with some sand and cement and airtightness paint.

If it is just for storage, 2.5mm 3 core steel wire armoured that can be buried direct, but in duct would allow you to change it for a different cable if needs change.

@Ferdinand it’s very manual (so not very passive) and relies completely on my unhealthy obsession with the outside air temperature. The blinds and MVHR could be automated I suspect but not the door/window opening.

It certainly is. Just back from my local after 3 pints of Thistly Cross and a bag of steak ridge cut McCoys. Just me, the pub cat and a paperback in the sun trap garden.

We clearly have similar tastes 👍

Yeah don't quote me on that, sparky is coming in soon, that's just from what I've seen. Cool, we'll do that, thanks for your help

I really like the way our house looks with the blinds down. but I am a bit biased!

Thanks for at least calling me a plumber !

We should never make holes in webs or flanges without a check. In reality there is usually some spare load capacity, and spread out fixings will be ok....but a phone call to the SE is likely to result in a straight forward 'no problem'. Also consider out of balance loading..If the timber is all on one side, then the load will twist the beam....which is bad thing. I prefer to fix using purpose made 'timber to steel' screws. This allows for careful tightening , and some adjustment. Concealing the head without risking pull-out may require consideration.

It's Warmcel

I've just been up on the roof scrubbing my solar panels. They were filthy after the farmer's harvesting around us coated them in dust but I still don't get much improvement in performance. They're on a tin roof and my 5kWp of panels is maxing out at about 4kWp during this hot weather. It's really irritating that there's a 20% loss in performance when they get warm. They are on a tin roof and it's cooking* hot up there though. * This being a standard unit of temperature somewhere after 'really' and before 'nuclear'...

But the roof is in shade so as long as there's an air gap under the modules, it's pretty much irrelevant what they mounted on. I saw some pwople were experimenting with water cooling PV to increase output. Not a realistic proposition I would think although it did seem to gain a little.

You can get a post level: https://www.screwfix.com/p/post-level-5-125mm-/6872V?

Probably not. You have to look at the raised temperature in conjunction with the extra radition that they are getting. We tend not to get exessive temperatures without excessive radiation in the UK (thare are odd exceptions where a wind blows over a mountain and, as it falls to Earth, compresses the air and heats it up). So if a module is tested a 20% converstion efficency, at 25°C anC d at 800 W/m2, and for every 1°C above that it looses 0.5%, at 35,you get 138 W/m2 of electricity. If you tested it at 35°C, but at 1000 W/m2, you get 171 W/m2 out. (not exact figures, but highlights how the 'efficiency' is measured) The other thing is that during those fairly rare high temperature events, you don't need much electricity.

Sadly not an option for me, as I've uneven joist distances in the old part of the house, and they're not recommended for heat pumps, which may be an issue in the future. I'd much prefer the quick and simple approach though, this is looking like a proper headache.

Thanks for the responses. I will be taking out the light fitting etc before plastering. I was wondering whether or not this will require the fibre tape on it or will they just plaster onto the metal part without the tape.

You would assume so . I’m sure I read in a few places once temperature starting exceeding 25degs you lose 1% efficiency per degree . Tbh the efficiency downgrade must be minimal. By 11am in the current weather I’m almost maxing out my PV generation anyway .

Be interesting to know what the temperate differene is between PVed and unPVed roofs. Maybe a project for when you get it fitted as I am ausre there will be a bit that is not covered.

It uses little bandwidth when he’s actually playing games on it and you can control when it downloads updates. If he’s downloading a new game then he does that at a convenient time for everyone else in the house. I don’t quite get the problem to be honest as there options to manage it. That said if you had a much faster service and didn’t change any of the settings on the Xbox so everything was as it is now then I doubt you’d notice a degradation of service for the rest of the house. It’s only noticeable just now because you are very bandwidth limited. I wouldn’t mess about with multiple bonded setups. Talk to your neighbours that use the WISP service. If they have have had a positive experience then talk to the supplier. They will have several offerings including a guaranteed minimum speed offering I expect although that’s probably a business plan.

No problem : router: https://www.amazon.co.uk/gp/product/B07ZFSX8LB/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 Antenna: https://www.amazon.co.uk/gp/product/B00C1DGFPS/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 Very much a diy install. What I did was I got a selection of free payg SIM cards and tried them all alongside holding antenna outside every window to establish best combo of antenna location / provider. In my case the antenna & router went at one end of house so a simple plug in WiFi booster takes the signal around the house. Certain there will be more geeky ways to establish signal etc but I’m a simple person. if you do go for this kit via Amazon & try with various existing SIM cards / free pay ones obviously if it just doesn’t work for you can return everything easily at no cost/risk. That how I looked at it.

Or keep it if you have the room? That is what we did this time around. It is now in effect a massive garden building for far less money than you could ever buy any form of shed or other building that size for.

Yup, local advert and chap offered to buy it and collect 👍

I advertised mine on gumtree, and the buyer organised a proper transport firm to come and collect it. All I had to do was get it off the stands and disconnect the services so it was ready to collect. Make sure to state buyer arranges transport.

Facebook marketplace and Gumtree are probably your two best options. Obviously self-build sites are good places too. You just need a bit of due diligence when folk contact you about how they are going to remove it. Have you tried any of the static caravan places? If it’s in reasonable condition they might be interested.

Let us say that you can get PV installed at £750/kWp. A kWp will generate between 850 and 1050 kWh/year, depending on where in the country you are, and how well orientated your system is (any fool can make a PV system fail). Assuming that 50% of the PV is self use (the other 50% helps to keep others bills down), then that is, in effect, £1500/kWp. Taking a ten year life (which is very low) that is £150/kWp. Taking a median generation of 950 kWh/year, £150/ 950 kWh/year is £0.16/kWh. Or 12p cheaper than imported power.

They come out fine. Make sure the ‘guts’ are stripped out and tell the plasterer slowly and clearly they need to be spotless. Then remind him before he starts 😉

Just two wires here to each photocell. I've had them connected to the board on the bench and checked their function: As it stands I've just got photocells 3 & 4 fitted. The aforementioned red/black is if I fit a pair of photocells as "8" on the diagram. I'll likely get some wireless contact strips instead:

Maybe a plume kit to manage the plume from the boiler

Anything but (in our case at least). Right now nearly every window is tilted open and will stay that way until morning whilst the house takes a big long breath of cool air. In the morning when the outside temperature gets to that of the inside temperature then everything will be closed up and the house will keep its cool until tomorrow night when we will rinse and repeat. We also turn the MVHR down to its lowest setting when it’s properly hot so that it’s not breathing in more hot air than absolutely necessary. It’s worked a treat - no overheating at all.

Light pressure and speed as @Nickfromwalessays...plus a cowl with a large flange to hide any mess... Are you drilling a table end in the loft space? If so I'd say there's no need to seal that particularly.

Looks to be grey (is it really or is that just what the picture shows) so most likely armoured telephone cable. Dig a bit either side and push it over a bit for your post. Wrap the bit of outer sheath you have damaged with self amalgamating tape.

The house next to us, the owner / builder realised on the morning BC was coming for final inspection, that he had not fitted an extractor in the utility room. So he quickly cut a hole in the plasterboard and fitted a fan. It is not wired and not connected to outside. BC did not notice and it has been like that for 19 years through 2 changes of owner and still doing nothing.

Ah, OK. When screwing the plasterboards to the studwork, you should make sure there is timber, and that you screw into it, at the position that the tray will be bonded back to the plasterboard. That make sense?

Aluminium spreader plates for me, just so quick and simple. Great results every time.

What the …. is the point of the MCS if they aren’t able to provide sensible guidance when needed? And then the fact that none of the MCS installers know what is going on. Madness.

That'll take some explaining lol 😆

To highlight that point, our neighbours have just returned from a weekend away, probably to a hot house, and they have now opened all the windows. It’s lovely and breezy out there, but it’s also 30 degrees out there so they will be filling they’re house with 30 degree air which probably isn’t for the best. I could go and tell them but as they don’t speak to us since the slab was power floated, I won’t bother. 😁

Was a podcast on the Beeb about it the other day. Hopefully @Onoff will print us one up.