Improving energy efficiency & air quality/humidity in an 1850s stone house

[GerOR]

Hi everyone,
I recently bought an 1850s two storey detached house. The walls are 2ft thick stone and brick.
We only learned afterwards that old houses should not be treated with modern methods of insulating, gypsum plaster etc(wish we had knew this before we bought).
It's our house now and we have to make do with it and try make the best of it.

The old owner removed old oil central heating and replaced with electric radiators (modern ones)
Electric bills are fairly high to keep the house warm.
We have a wood burning stove and that does help.

We are almost certain we are going to get 18 panel solar system with battery and hot water diverter.

I was wondering if anyone would have other suggestions for improving energy efficiency of house. I know a modern plumbing system might seem like a good idea but I do like the way we can control each electric radiator individually and we can program them to come on and off on a daily schedule.

We wanted to dry line(build a timber frame around the room and use mineral wool insulation) but this has mixed reviews.

We renovated the whole house before we move but did not consider the benefit of floor insulation and we have all new wooden floors and tiles gone down and pulling it all back up so soon after moving in is not an option.

I hear air to air is a good system but I imagine it needs proper insulation. Would air to air be better than electric radiator for an old house?

Attic is insulated.

Also some of the rooms particularly bedroom have higher humidity than I would like around 70% upon waking. We open windows and do use a dehumidifier but it's not a long term solution.

Any suggestions would be much appreciated.

Thanks a mill guys.

Ger

 

[Mart]

Hello,

Things I'd consider.

• Solar and battery is good, I wouldn't bother so much with the hot water diverter. As you'll stay with electric heating (whichever type you decide on) invest in a large battery or multiple. I've time of use tariffs allow me to drastically reduce my bills by charging the batteries in the cheaper times and getting over the expensive bumps (4-7pm) without drawing from the grid.
• As you want flexibility air to air sounds like it would be ideal for you - that would be a huge and immediate improvement in your energy efficiency air to air would provide you ~3x as much heat for the same energy compared to electric heaters. You can get air to air systems which will also heat your water. There are loads of youtube videos comparing pros and cons on air to air vs air to water heat pumps. Getting through your walls might be fun!
• Air to air would also help with humidity, regular use of the stove will also help.
• Top up the loft insulation to at least 30cm, if you're reluctant to insulate the walls due to risk of damp why not go even further in the loft if possible.
• Basic draught proofing
• You haven't mentioned what windows you have, single or double glazed? If single you could consider secondary glazing.
• I've no experience in insulating walls but from what I've read you're probably right to be cautious.

 

[GerOR]

Hi Mart.
Thanks for your response.

I definitely intend to pack the attic with more insulation. It is only a crawl space so it's tricky up there!

I was unsure whether to go for 12 panel solar with battery and air to air system or just go for 18 panel solar with battery.

Trying to be as wise with the funds while we have them.

All double glazed windows. New composite front and back door also.

Solar seems to be the answer for sure. Me and my partner both agree no insulation in walls. I know you can get breathable insulations but again reviews are mixed.

There seem to be limitations on old houses and what can be done so solar and air to air seem to be two options that will benefit us while not affecting the structure(damp, mould condensation etc).

Thanks for your Reply Mart I appreciate it.

 

[Mart]

Most importantly remember period properties are great and worth the effort!

If you have the room I'd imagine an extra 6 panels would be negligible costwise, once they have the scaffolding up etc. I believe panels are about £100 each. If you have the space for 18 I'd do that.

Fully understand the funds situation. I have gas central heating but had solar and batteries installed with a plan to install a heat pump when I have the money to do so! Based on what you've shared I'd suggest...

1. More efficient heating - Air to Air would solve your problems of energy efficiency and humidity - I would think this alone would save you money due to the inherent efficiency of heat pumps vs electric heating.
2. You can then install solar and battery at a later date and save even more money, can take 7-8+ years to break even.

Worth noting that solar generation funnily enough needs sunlight . This will be at the polar opposite time of year when you need heating, although presumably you can sell energy back to your provider in ROI? Right now my panels are generating about 1-2kWh a day, basically nothing. My battery is being an absolute champ and has kept my average cost per kWh to 10p in Dec with a time of use tariff.

What I'm trying to say is it's worth you considering your energy usage and timings (i.e. what % of your energy bill is due to heating). That will help inform you of the best way forward. Reduce your consumption (heat pump) vs generate your own (solar/batteries).

It seems you've only recently moved in and are new to older houses, so I'd take your time to get to know it before making any big decisions - unless you're absolutely haemorrhaging money trying to heat it.

 

[Flyfisher]

We were able to connect to mains gas, which made a heat pump an uneconomic in comparison.

Last year we installed 20 solar panels (on a hidden ground array) and a home battery. The battery really comes into its own during the winter because while the PV panels generate far less power than in the summer, the battery can be charged overnight from the grid at 7p / kWh compared with about 28p, ie about 4x cheaper rate. Size the battery correctly for your usage and it can last the entire day, meaning that you rarely draw any full-cost power from the grid. My average cost per kWh in November was 8.6p, including charging my EV. During the summer months, the monthly electricity bill was negative for a few months, again including charging the EV, and covered the cost of mains gas used for DHW.

Underfloor heating can also help to 'time-shift' your energy demands. We have wet UFH in some rooms run mainly from the gas boiler. The boiler is actually under-sized and struggles to heat all our four zones simultaneously but by running only the two UFH zones overnight and then switching over to the two zones with radiators during the day, it can keep all zones warm (about 17-18c) as the UFH floors remain warm all through the day. We then use wood stoves to top up the room temperatures. Performance is definitely affected by the outside temperature, implying that our insulation could be better, but when it's above about 5c it all works well enough - we're not the shorts-and-tee-shirt types and jumpers are the norm in the colder months

We've evolved all this during the 15 years of renovations, so I very definitely agree with Mart's advice above about taking time to learn how the house 'works' throughout the year.
Maybe don't take 15 years though

 

[GerOR]

Hi flyfisher.

Thanks for your response.
can I ask what size battery you installed?

also what type of insulation did you use and where abouts? I'm assuming it's a stone house?

I'm getting to know our home more and more each day. It's a process but I am enjoying it but there can be a lot of setbacks as the old owners did not maintain the house well nor treat a traditional building as they were intended to be treated.

We plan to give it the love and attention it needs to make it our forever home.

 

[GerOR]

Most importantly remember period properties are great and worth the effort!

If you have the room I'd imagine an extra 6 panels would be negligible costwise, once they have the scaffolding up etc. I believe panels are about £100 each. If you have the space for 18 I'd do that.

Fully understand the funds situation. I have gas central heating but had solar and batteries installed with a plan to install a heat pump when I have the money to do so! Based on what you've shared I'd suggest...

1. More efficient heating - Air to Air would solve your problems of energy efficiency and humidity - I would think this alone would save you money due to the inherent efficiency of heat pumps vs electric heating.
2. You can then install solar and battery at a later date and save even more money, can take 7-8+ years to break even.

Worth noting that solar generation funnily enough needs sunlight . This will be at the polar opposite time of year when you need heating, although presumably you can sell energy back to your provider in ROI? Right now my panels are generating about 1-2kWh a day, basically nothing. My battery is being an absolute champ and has kept my average cost per kWh to 10p in Dec with a time of use tariff.

What I'm trying to say is it's worth you considering your energy usage and timings (i.e. what % of your energy bill is due to heating). That will help inform you of the best way forward. Reduce your consumption (heat pump) vs generate your own (solar/batteries).

It seems you've only recently moved in and are new to older houses, so I'd take your time to get to know it before making any big decisions - unless you're absolutely haemorrhaging money trying to heat it.

Hi Mart,
Yep in ireland we can sell back to the grid any surplus electricity we do not use.

We converted a stone shed at the back of the property for my mother in law so drawing power out there. I don't think we will be selling back to the grid we are high electricity users.

I imagine you have a fairly big battery to keep costs at the level? That's amazing. They really are worth the investment.

We are actually installing a ground mounted system we have 0.75 acre and it's all open so plenty of sun throughout the day. Our roof would only hold 12 panels are there is a dormer style window at the centre of the top of the house.

I appreciate your replies and your knowledge.

Thank you

 

[Flyfisher]

Hi flyfisher.

Thanks for your response.
can I ask what size battery you installed?

also what type of insulation did you use and where abouts? I'm assuming it's a stone house?

I'm getting to know our home more and more each day. It's a process but I am enjoying it but there can be a lot of setbacks as the old owners did not maintain the house well nor treat a traditional building as they were intended to be treated.

We plan to give it the love and attention it needs to make it our forever home.

My home battery is 11.5 kWh, though they don't recommend discharging beyond 10% so it's effectively about 10kWh.

It's not all that easy to size things before you have a good record of how much consumption you use, and then factor in any PV generation (if applicable). The pattern of consumption is also significant because if you can arrange your heavy consumption during the low-rate periods available then you don't need your battery to be working during those hours. Thus, when I got my EV it didn't affect the battery sizing because I only charge the EV during the low-rate periods when the battery is not discharging.

Also, if you have PV as well then the battery won't be used during sunny periods. These are obviously fewer during the winter months but even a few hours of sun means a few more hours of battery operation into the evening hours. From memory, I'm using about 26kWh per day on average, so 10kWh of battery might seem too little, but the 'battery day' is never more than 18 hours (depending on your low-rate tariff) plus I get additional low-rate hours throughout the day due to the 'intelligent' EV tariff, and the battery can be turned off during those times (no point using the battery when the grid is just as low-cost). Add a few hours of sunlight, even in winter, and that means the battery only has to work for around half a day and supply about 13kWh. Obviously, this average is more than my battery's 10kWh capacity, which is why it sometimes runs out by the early evening in the winter months. My battery is expandable in 5.8kWh increments, so it would be easy to increase and would then probably never fully discharge, but I've not yet bothered to work out the cost-benefit and pay-back period for doing this. My two rates are 7p and about 28p per kWh but my average rate is always below 10p each month and the lowest I can recall was about 8p.

Also, somewhat counter-intuitively, when I first got my EV, I envisaged charging it for 'free' using the excess PV generation but that turned out to be the wrong approach because I can charge the EV overnight at 7p/kWh and then sell any excess PV for 15p/kWh, so using my excess PV to charge the EV would actually be more expensive. It's all a learning curve!

As for the house itself, it's a 3-section mix of timber-frame/wattle&daub, rubble wall and chalk block all under a pantile roof and was in a very neglected and poor condition when I took it on. Fifteen years on and I'm finally working on the last room, though it has been a very much stop-go project over the years. It was always intended to be a forever home and I'm sure that's still the case, but 'forever' seems to be getting shorter and shorter . . . .

 

[Cubist]

Also, somewhat counter-intuitively, when I first got my EV, I envisaged charging it for 'free' using the excess PV generation but that turned out to be the wrong approach because I can charge the EV overnight at 7p/kWh and then sell any excess PV for 15p/kWh, so using my excess PV to charge the EV would actually be more expensive. It's all a learning curve!

All of which reminds me - I bloody well hated Algebra at school... and my attitude towards it hasn't changed a jot!

 

[Mart]

Hi Mart,
Yep in ireland we can sell back to the grid any surplus electricity we do not use.

We converted a stone shed at the back of the property for my mother in law so drawing power out there. I don't think we will be selling back to the grid we are high electricity users.

I imagine you have a fairly big battery to keep costs at the level? That's amazing. They really are worth the investment.

We are actually installing a ground mounted system we have 0.75 acre and it's all open so plenty of sun throughout the day. Our roof would only hold 12 panels are there is a dormer style window at the centre of the top of the house.

I appreciate your replies and your knowledge.

Thank you

We're a relatively low usage household, no EV and gas heating. So probably use an average of 12kWh a day. Battery is 9.5kWh but it does the job between frequent top ups.

I'm using home assistant to automate the charging and discharging based on the half hourly price of electricity, now its set up up I pretty much leave it to it's own devices. As Flyfisher says battery is plenty big enough and the automation will draw directly from the grid when it makes sense.

If/when I move to a heat pump I would consider a bigger battery to ensure it could make it through the expensive periods but that would be a 'wait and see'. You then do get into issues with inverter size - limits on how quickly you can charge and discharge the batteries which I've not looked in to.

I would think if you're planning on a ground mounted system going for the 18 would make sense, a few additional panels should be fairly negligible in the overall costs!

 

[Flyfisher]

Well done on using HA to track the half-hourly cost of electricity, you're clearly further up the learning curve than me!

I agree with your 'wait and see' point. Do the obvious basic things first but leave things open for subsequent expansion and/or modification.

Regarding the speed battery charging, I've found this can vary quite considerably with temperature. My system is installed in an unheated outbuilding and when the temperature falls below about 4C the charging time increases quite a bit. My battery is set to charge at 11:30pm and even when fully depleted (to 10% SoC) it will usually be charged to 100% by about 1:30am but in colder weather I've seen it taking until 3am. This is not a problem for my current usage pattern but would be a consideration if I was trying to track 30 minute prices. I've been thinking about building an insulated box around the battery so that temperature doesn't fall so much, though I'd then have to be mindful of things overheating in the summer months.

 

[Mart]

Ah yes temperature is another issue. My battery has had a recent update that throttles charge/discharge when it's below 20C - which is often this time of year as my battery is in an unheated garage.

HA has been great, I use an add-on called Predbat. Very smart tool.

 

[GerOR]

Thanks for all the knowledge guys. I will keep you all posted and what we end up deciding to do!

 

[Flyfisher]

Ah yes temperature is another issue. My battery has had a recent update that throttles charge/discharge when it's below 20C - which is often this time of year as my battery is in an unheated garage.

HA has been great, I use an add-on called Predbat. Very smart tool.

I'm guessing you mean below 2 degrees C

My battery (Solax) definitely throttles its charging when cold, which I can easily see from how long it takes to regain a full charge overnight, so I guess it also throttles discharge as well though I've never really noticed that, probably because the grid would take up the slack in such circumstances anyway. The control systems for these batteries are pretty 'smart' these days and should protect the battery from adverse conditions.

I've not heard of 'Predbat' but will look it up. It's quite amazing how much good stuff is out there these days.