Hi all, and thanks @transparent for pointing me here.
I'm new to RHH but have really enjoyed reading posts over the past few weeks. I'm about to start renovating our home and and keen to future proof it as much as possible, to minimise our carbon footprint but also domestic running costs. I live in a detached 1930s house in NW10 in London with a south facing roof. It's poorly insulated, in fact we found out today that our current air permeability is 17.5. I don't know what that number means but I understand a Passivhouse is 0.6 and I was advised today that we should get to 5.
As part of the renovations we'll be getting the house fully insulated, externally, and installing new windows and doors all with U values no more than 1.4
Additionally, I'm looking at Solar PV with a battery, as well as switching to a tariff where I can fill the battery overnight at lower rates on days when our solar generation is insufficient for our needs.
We will also install MVHR and an ASHP. I'm assuming we will need a new hot water cylinder to optimise the heat generated by the ASHP and to also use the power produced by our Solar PV.
I'm not technical, certainly not in this sector, but want to do my bit for the environment as well as doing what I can to reduce our running costs once we've installed everything.
I have a few initial questions:
1. Has anyone come across a single supplier who could manage the supply and installation of all these services? Or am I better off using specialists?
2. Is it worth appointing a specialist MEP consultant to help define our needs and then design a system for which we'd ask suppliers to quote against?
3. What do Heat Geek offer that gets such good praise and reviews? From what I can see I think they're a network of good ASHP installers with an entertaining youtube channel, but I'm just checking if there's more that I might be missing?
4. I've read a bit about operating systems (eg Homely, Havenwise etc) which seem like a great idea for ease of management and information, but i've also read some people think they can have a negative impact on the efficiency of a system. Does anyone have a view on that?
5. Does it really matter what battery you get for solar PV as long as you put in enough capacity for what you can generate or need? As long as I pair it with something like an Eddi solar diverter?
5. More generally, apart from having Evohome (Honeywell) thermostats at my last house which felt very innovative to me at the time, this is my first foray into this world of ASHP, MVHR and solar etc, so any general advice would be greatly appreciated.
How much of this renovation would you like to undertake yourself? Or are you simply wanting to throw money at contractors to achieve results as fast as possible?
You might suppose that it's beyond you because you're "not technical".
But if we handled the technical stuff on this forum, would you like to be hands on?
Bear in mind that much of this forum contains assistance for members who have had sub-standard work done by contractors.
Genuine self-builders don't have that sort of problem. They're unlikely to do shoddy work on their own house!
I'm now away for the evening... attending a community-energy seminar. 😎
Hello Nick, I hope you will document your progress as it will make very interesting reading for many readers. I have done a few of the things you plan to and you will find a few minutes reading here:
I have Homely smart control and find it to be very good at looking after my comfort needs via our Daikin ASHP. If you are fortunate enough to have well orientated spaces for solar PV - I suggest you go for as much as you can accommodate! Panels are cheaper now than ever before and whilst fitters are using scaffolding (at a cost of course) you might care to avail yourself of all the area you can. You will find lots of discussion about such matters as Time of Use Tariffs and suppliers and people are beginning to chronicle their journeys to an installed system in this very organ. Regards, Toodles.
@transparent I won't be doing much of the work myself unfortunately, more due to my time commitments than a willingness to have a go, but I understand that means things come at a premium.
@toodles Great article. Thanks for sharing - very insightful and helpful. Which brand of thermal storage did you go for? Our renovations will convert our house into a 5 bedroom house with 3 bathrooms. Would such units be capable of providing hot water for that scale?
@nickmorgan We have a Sunamp Thermino eP210; this may be charged via the Myenergi Eddi with solar or grid energy. The recommendation for sizes is matched by a range of capacities (our being an equivalent of 210 litres, but at approx 25% of the volume of conventional DHW tanks. We had nowhere to fit a tank and didn’t fancy modifying loft acess for a tank - at the time we started our research into siting a DHW tank in the loft, Octopus Energy were not fitting them there anyway
I won't be doing much of the work myself unfortunately, more due to my time commitments than a willingness to have a go, but I understand that means things come at a premium.
Using contractors also provides opportunity for them to get things wrong.
So it's still important to understand the basics of what you're asking them to install. Ideally, you should be specifying the hardware you want, rather than giving them free-reign to select items.
As part of the renovations we'll be getting the house fully insulated,
What about the roof/attic space?
I opted to replace the insulation which was above the ceilings with solid PIR boards in the roof itself. That's called "warm roof construction" and means the attic space is within the thermal envelope of the house.
The rafters were nominal 4-inch.
I put 50mm Celotex boards on top (beneath the slate battens) and 75-80mm between the rafters.
All the PIR boards were B-grade from the likes of Seconds and Co in Wales.
Does it really matter what battery you get for solar PV as long as you put in enough capacity for what you can generate or need?
Yes. It matters a lot.
The most respected Battery and Inverter manufacturer in UK is probably GivEnergy.
But have a look at this topic where we discuss their new range for 2025.
They are changing to a system which uses 'high voltage' batteries in series, rather than the more common parallel-arrangements (such as Pylontech - photo below)
As a consequence of that:
additional battery capacity is only achievable using more GivEnergy battery modules
only certified electricians can be installers because they operate above 75v (the limit for Extra Low Voltage or "ELV")
The main alternative route is to stick with the usual 52v Lithium Ferrous Phosphate (LiFePO4) battery configuration in parallel. You can then use any inverter system you choose...
... but I'll suggest SunSynk is likely to be a strong contender!
Pipe joins, adaptors and air inlet/outlet points are readily available.
Pipe runs covered in bubble-wrap can be fixed to supports using the plastic clips for 110mm waste-water pipes. There are two sizes of these. You need the ones stamped "Socket" rather than the "Pipe" clip.
This post was modified 1 month ago 2 times by Transparent
Pipe joins, adaptors and air inlet/outlet points are readily available.
Pipe runs covered in bubble-wrap can be fixed to supports using the plastic clips for 110mm waste-water pipes. There are two sizes of these. You need the ones stamped "Socket" rather than the "Pipe" clip.
Totally agree.
We had our MVHR pipes put in first (6inch like above) and the guy who installed it was great. He took my plans of the house and pipe layout and worked with that. Most of the pipes went into the loft above the joists which had 6inch of insulation between them, then 200-300mm went over everything.
On every vent into the rooms there is a flexible expansion section so no vibration /noise gets transferred
He did say it was a pleasure to work before everything else (such as heating pipes and water pipes) went in and in a large space between floors.
We’ve had the system extended with modern rectangular pipes and that section is noisy particularly when the system is on boost. But it’s much lower levels than the cooker fan for instance just we’d got used to nearly nothing.
We did consider DIY but that 4 letter word WORK got in the way.
2kW + Growatt & 4kW +Sunnyboy PV on south-facing roof Solar thermal. 9.5kWh Givenergy battery with AC3. MVHR. Vaillant 7kW ASHP (very pleased with it) open system operating on WC
Nick - Fitting large pipes is one of the most enjoyable DIY jobs you can have.
Whether it's foul-water drains, rainwater or ventilation, they are very easy to measure up and join together. It's like having a set of LEGO, where everything just pushes together and stays there.
The main part of the work is lifting the flooring in the first place. But would you really want to be paying a qualified tradesman just to do that anyway?
When I lift a board, I put in whatever the required pipework is, and then 'tack' the board back in place using a couple of screws.
That makes it much easier to install other services at a later date.
If that section of floor happens to be under some particularly heavy furniture, or in an awkward location, then I put in a piece of polypropylene garden twine with a nail tied to each end. In later months, that might allow me to pull through a water-pipe or an electricity cable.
In the following photo you can see where I'm starting to build a new stud wall on the left. The doorway in the background is to be removed.
Instead of the usual 75mm deep timber uprights, I'm using 125mm for the timber-framed wall. That provides the space for two ventilation pipes to rise into the attic, and a hidden air-inlet valve on a waste-water pipe which serves an en-suite bathroom and cloakroom below.
Next to one of the silver-wrapped ventilation pipes you can see two 8mm black cables. Those are wires for TV points, supplied from the distribution amplifier in the loft.
There's few rules which tell you what to do.
Apart from the air-inlet valve being higher than the wash basin in the en-suite, nothing else I've described is defined by Building Regulations. The piece of brown tape on that valve reminds me that I haven't yet glued it in place.
Just use common-sense!
This post was modified 4 weeks ago 3 times by Transparent
Thinking about installing a heat pump but unsure where to start? Already have one but it’s not performing as expected? Or are you locked in a frustrating dispute with an installer or manufacturer? We’re here to help.
