I'd've thought something like this would do

https://www.amazon.co.uk/dp/B07W96HH2S?ref=emc_s_m_5_i_atc

I hasten to add, that link is for illustrative purposes only, not as a recommendation. However, it does show the basic idea that you can programme a temperature and have it activate an electrical socket above that temperature where a fan or other cooling system is plugged into that socket.

The more important point, though, is that the fan won't do any cooling; it'll only move air. In your situation, I suspect I'd install some ducting going down to the soffits so that a fan or fans can blow warm air out of the loft void entirely and so achieve some practical level of actual cooling.

Posted by: @majordennisbloodnok

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I'd've thought something like this would do

https://www.amazon.co.uk/dp/B07W96HH2S?ref=emc_s_m_5_i_atc

I hasten to add, that link is for illustrative purposes only, not as a recommendation. However, it does show the basic idea that you can programme a temperature and have it activate an electrical socket above that temperature where a fan or other cooling system is plugged into that socket.

The more important point, though, is that the fan won't do any cooling; it'll only move air. In your situation, I suspect I'd install some ducting going down to the soffits so that a fan or fans can blow warm air out of the loft void entirely and so achieve some practical level of actual cooling.

Sounds good, @david999, although I suspect you'll need several vents and plenty of forced-air movement to achieve the level of cooling you're after.

I think it's going to depend on the size of your loft. The amount of air you can actually move with a fan isn't huge and it'll also often fail to move the air you care about unless you want to stick it right by the inverter and potentially duct it around the inverter. It's also going to be air (not a great carrier of heat) versus sun on roof (which is) so the fan may lose the battle and most of your temperature end up defined by the balance between the sun on the roof and the existing losses at the high temperatures.

The pokier the space you are working with and the more it looks like a chimney the better it will draw and cool if you can get the venting in the right places.

At least it's cheap to try.

@etchedpixels the more replies and more thought I give this the more I think it’s not practical. Must be a lot in lofts though before they changed the rules, but at side of house and in an unheated garage would bring me here discussing condensation and the cold wet weather issues.

Posted by: @david999

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@etchedpixels the more replies and more thought I give this the more I think it’s not practical. Must be a lot in lofts though before they changed the rules, but at side of house and in an unheated garage would bring me here discussing condensation and the cold wet weather issues.

Not necessarily, @david999. My Growatt inverter and battery are both outside (IP-rated units) and the cold and wet weather have been no issue at all. As always, the kit used is less of an issue than the design of the system.

@majordennisbloodnok not a truer word spoken, as with ASHP the technology arrives before the skills.

I wish I’d known then what I know now, though. Our system is well designed for environmental factors but somewhat inadequate in other ways. When we upgrade (not soon) we’ll definitely be making some fundamental changes.

@majordennisbloodnok I had a huge battle with both my solar and ASHP installation. All sorted but I wish I knew more as well.  I’m watching houses being externally clad, retrofitted, and wonder if this is the next mistake. Thankfully not me. In terms of upgrading, perhaps technology will move onto something else, solar goes in a skip and we will all be discussing our issues here with that.  We certainly are in a transition period and our new power source may be around the corner.

Posted by: @david999

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@majordennisbloodnok I had a huge battle with both my solar and ASHP installation. All sorted but I wish I knew more as well.  I’m watching houses being externally clad, retrofitted, and wonder if this is the next mistake. Thankfully not me. In terms of upgrading, perhaps technology will move onto something else, solar goes in a skip and we will all be discussing our issues here with that.  We certainly are in a transition period and our new power source may be around the corner.

"Next ?". We already know EWI is in most cases going to be a spray foam grade disaster. It's like all of these things though. The UK work is done as cheaply as possible with the cheapest inappropriate materials by people who mostly suck because they could earn more in Aldi than on site. The ECO4 mess is going to cost more to get all the houses back to the state they were in before EWI was added than the grants paid out in the first places.

Retrofits can be done well, but it involves having people who can explain phrases like "dew point", understand building fabric and historic building design and aren't handed a contract by a large commercial landlord or social housing provider to do "as many houses as humanly possible for £x". Unfortunately it's an industry that makes heat pump and solar installers look reputable.

Good EWI exists. It's breathable, it works with the building, when you get water into it (as you *always* will) then it can escape. It just costs somewhat more than covering a house in impermeable foam blocks and cement and then waiting for the invisible leaks that will eventually get you even on a good install.

The fact EWI is also often fitted in conjunction with masses of other insulation and people skip MHVVR and other essential parts also doesn't help. Not all the black mould catastrophes are leaks - simply not providing enough needed ventilation as a result of other improvements can get you.

IWI has its own set of problems too because older houses rely on things like the joists being warmed by escaping internal heat, so IWI done wrong means your joists fail a decade later and your floor collapses.

We had various types of insulation fit including ewi some iwi and some breeze block with ewi and iwi and following building standards.

But no eco4.. so much volume of insulation has been done on that and at so much cheaper cost than non eco4 work that inevitably there would be quality issues..