Simon R

It depends on your budget and how much use they'll get. The main advantage for me was the lack of joints. Reco surfaces have an option to print your photo which gives pretty limitless options and it's not expensive. Here is a thread you may find useful:

I think we're both suffering a bit of confirmation bias, I could easily be wrong. The carbon intensity if the grid is not linear. The very times I'm using electricity are the times when the grid carbon intensity is at it's greatest. If having a battery helps smooth this great. I would love to think that if enough people had batteries it would prevent the firing of a gas turbine. Think local , act global. I'm not an expert, but I do care.

Yup, that's precisely what I find is the case. Energy generated and stored during the day is used to run the house to cook supper, watch TV, do the washing and make breakfast all done when the sun is not shining. Of 7MWh generated 4MWh went into the house and 3 got exported. Without a battery far more would have been exported as it is generated at times when we couldn't use it. Any residual left in my battery gets used to charge my EV leaving just 20% in the battery to get me through breakfast and into PV time. It's not perfect by any means but it helps.

I must confess I’m slightly intimidated when replying to your post….. I don’t think that any sane person would argue that the figures on atmospheric CO2 are just horrible. There are quite a few carbon sequestration options around but few are showing anything like the promise to be able to do the job, which is depressing in itself. Getting control of atmospheric CO2 is the biggest challenge facing humanity. Moving on….I’m trying to get my head around the figures. Google informs me our generating capacity is in the order of 101GW (2022 figure). Energy consumption total in the region of 1,729GW, so a factor of 17ish short when it comes to consumption. That’s a lot of additional generation capacity required and the goal of being oil free is a long way off. Housing accounts for something like 14% of the UK power consumption. Some 5% houses in the UK have PV installed, depending on what figures you take 50-65% are suitable for PV installation. If I could use my EV battery to buffer my use, it would be better than having a separate house battery. However the standards aren’t there and even if they were it would not be a universal solution. For me it’s the ‘ant pissing in the ocean’ approach, every little helps, even if it’s apparently inconsequential.

Well, it's true I'm considering PV input to the battery as carbon neutral. If I didn't store any electricity, any residual from local consumption would get exported, which all helps decarbonise the grid. If the grid was carbon neutral then there would indeed be no case for batteries. With a battery in place I use very little electricity from the grid and the times at which it gets used are typically outside the times when solar is being generated. If a battery was not available this would have to come from the grid with the associated carbon cost. In an ideal world it would be great if EV's were grid linked when plugged in and their batteries available as a supply/demand grid buffer. There are moves to make this a future possibility, but like all things it's more complex than it would at first seem.

While it's true that consuming is environmentally negative, investing to use less in the future is not environmentally negative. Without it we would not have solar or wind farms. Building to passive house standards consumes more resource, but pays back in reduced energy cost over the building life. Similarly running an EV is less damaging that running an IC over the life of the vehicle. Backup for the grid was not a consideration in my choice to install a battery.

It's a case of don't post when jet lagged.... My 7MWh figure is total from 28/10/2022 not this years PV generation which rather changes the figures. However it still does not take long for a battery to become carbon neutral which is the important issue.

I've just checked my battery discharge figures and I was including electricity directly from solar. The battery data shows a a discharge of 2.8mWh for the year so it's taken me around 14 months to become carbon neutral, still a very positive reason to have a battery.

Hopefully I can help. I'll start by admitting I'm in favour of home storage, so biased in my thinking. This is back of a fag packet stuff.... 1kWh requires 58kg of co2 1kWk generation 162g So it takes about 358kWh of battery use before they are carbon neutral. Our 4kWh solar installation generated 7mWh last year of which we used 4mWh the remaining 3 got exported. For our 9.2 kWh it took 533kg of co2 to manufacture (lithium phosphate so no cobalt) To be carbon neutral we need to use 3,293kWh (3.29mWh) of grid generated electricity at 162g/kWh Based on our usage of 4mWh we are already carbon neutral in the first year ignoring the 3mWh we export. So if you manage to use all of your PV generation you'll be carbon neutral even earlier! Yes, I've ignored the co2 associated with the inverter as you need one to manage any PV in the first pace. I think it's two years for a solar panel to be carbon neutral. Financially Back in December I posted on a thread on battery sizing. Our battery gives us an annual saving in the region of £1397 given my system outlay was 6.5K that's not such a bad return.Current data on lithium phosphate suggests they are going to last a long time, a 12 year unlimited charge/discharge warranty is not exceptional.

I just estimated based on room air volume requirement. The largest flow with no restrictor, then the others as a percentage of the largest flow ( I didn't use restrictors in any of the returns). Using pi r2 to calculate the rings to remove. This works out at approximately 70,55,36,19,16% which is a reasonable starting point. Having done this measure the flows with the room restrictors fully open. If the flow was too low then remove another ring to get to the right sort of volume +-20%. As changing each restrictor affects the pressure in the system you may need to repeat the process. I would not bother trying to be too exact, it really is a diminishing returns exercise I called quits when within 20%. Once you get to this point you can then adjust the MVHR fan speed to get the required flow in the room with the largest. The other rooms should also be correct at this point. After setting up this way I found that in practice I could run the MVHR at a lower fan speed and still have a comfortable environment (almost silent).

I'd strongly urge you to take an in depth look at airtightness, it's fundamental if you want a draft free low energy house and needs to be designed in from the start. MVHR noise even with a loft installation should not be a problem, just a very low background hiss that you only hear when there is no other noise. Re-allergies, our kids and visitors lover our house during pollen season as they don't suffer with their hay fever.

Mike, you may like to consider using these. Mr Harris put me on to them, the idea is that you keep the air velocity down to a minimum in the tubes by installing these restrictors at the plenum. You pop out the restrictor rings as required. It's a bit of a fiddle as it's an iterative process as you balance out the flows.

The figures we got from the SAP calculations suggested we only needed a couple of kW to maintain a 20c temperature difference. As we had gas available we decided on a 3kW combi boiler to provide hot water and heat two towel rails and a single radiator in our living room. It has worked out well both from a comfort and budget point of view. We did have a problem with too much solar gain which we solved with a a small A2A unit which has ended up being used for heating in preference to the gas boiler. Installing an ASHP and UFH made no sense given the 2kWh input requirement and saved a lot of complexity and budget.

We initially wanted a polished concrete finish, fortunately our builder talked us out of it and we ended up putting down self levelling screed topped with vinyl planking.

Good point, our raft cost 5,248 just for the eps. Quite a bit of money, plus another 20k for the ICF blocks, with a total construction cost around 150K for the completed structure. I can't equate the cost to a conventional build. The result was considerably reduced risk and a very quick construction time. It's so well insulated that we didn't require UFH, the slab is the same temperature as the house even in winter, no need for slippers etc. and an annual heating bill around the 300 mark. I don't doubt the cost is higher than a conventional build but the comfort is worth every penny.

I agree completely. Our build is on clay over gravel (Bracklesham beds). The structural engineers we used were Tanners who used input from our soil samples. Yes, it's move expensive that strip but the results in terms of insulation are worth it. Regarding strength, these raft are recommended for earthquake areas.

I fell foul of this when submitting my VAT claim to HMRC. I did manage to get the correct invoices from the companies involved easily though. Any delay with HMRC is best avoided.

One would have thought so, but it's not universally the case. My MVHR (which I'm very happy with) is the Blauberg SB-550. It does not have PH certification, the SB-350 does. Given the unit efficiencies are the same, I asked Blauberg why the 550 unit was not PH certified. The reason is cost, they sell far more of the 350 units and could not justify the cost of certification on the 550. True you don't need to have all your components certified to get PH certification, but it's probably a whole raft of pain to use units which are not certified. Our house meets PH requirements and comes in at less that 15kWh per metre per annum. I'm in no rush to get certified, but very grateful for all the work that has been put into PH design.

My experience from four years ago was that components like windows, MVHR and even ICF blocks carried a significant premium for PH certification. That may have changed now it's more main stream.

Like Joe90 we built to passive ideals but did not agree with certain aspects of the standard. In particular the need for and ASHP. The whole point of passive is a focus on energy reduction. A house built to them frequently doesn't consume enough energy to make and ASHP install sensible, the alternative of a low cost A2A makes more sense. Understanding the basics of passive build is fundamental to reducing inputs, certification isn't. I can't overstate the benefits of living in a house built on the passive principles, it's an incredibly comfortable living environment.

I found the same with our build. Heating was a problem that wasn't predicted by our SAP calcs. Fitting an MVHR is a expensive but it does provide a very comfortable living environment in both winter and summer. The energy conservation is a factor year round. Typically our input/output air temperatures are within about 1.5C so in winter with the outside air temperature down at 5C and the house running at 22c the incoming air into the house is at 20.5C having been heated by the outgoing air at 22C. In summer with the A2A cooling on the house is still at 22C with the outside air temperature up to 28C the outgoing air is cooing the incoming air to 23.5, not a lot but it all helps. I was initially concerned over the operation of summer bypass, but it's easily disabled. It's all about saving energy. I'm not sure what the payback period is like but purely in terms of a comfortable environment I'd not want to be without an MVHR.

Your SAP calculations have a W/m2 and a W/structure per degree C values. Multiplying these by the HDD (Heating Degree Days) for your location or any other location will give you an idea of the annual energy cost.

I'd put it in as late in the project as you can manage. Our went in after we had painted! Yes, it was a pain having to use ladders internally but it was also good having the open voids to get material in. Installing as late as possible also reduces the risk of damage which you want to avoid as much as possible. Fontanot do a very nice modular stair case with a good rage of different wood treadles which won't break the bank. It's a very minimalist staircase so not to everyone's taste .

We also went this route having decided that an ASHP was an overkill for a property that didn't require much more than 2kW heat input. We're into our second year and it has worked out very well for our place which is open plan as the one A2A unit takes care of the whole house for both winter and summer. Our annual consumption for the house was 538kWh last year which included cooking , lights etc BUT not hot water which is provided by a small combi boiler. Installation cost less than 2K and it's a very comfortable way of heating and cooling. Considerably simpler than an ASHP and underfloor heating.

It may be worth considering an outfit like Beastons https://www.beatson.co.uk/ they do all sorts of fan work.