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The MiL is greenifying her house. (largeish 3 bed semi, bit draughty).
She's done the doors and windows, insulated the loft, and recently had a battery installed to go with the solar panels she's had since about 2010.
She's currently on a combi boiler - is there a better / more sustainable way to heat the house, perhaps making use of that battery?
More insulation, more draft proofing.
Repeat above.
The last thing I would do is put (likely quite significant) money into different heating systems in an existing house.
The last thing I would do is put (likely quite significant) money into different heating systems in an existing house.
The ASHP advocates will be on shortly...
Personally, I think draft-proofing, doors, windows, more loft insulation, etc., is eminently sensible. The battery I'm not sure about, however.
Assuming she's done the walls, what's under the floor? And is there a sanitary space big enough to be able to unsulate it from below? When you've done everything else doing under the floor makes a huge difference, far more than you'd expect given that heat rises and all the diagrams about heat loss show the loss through the floor as minimal; IME it isn't.
If it's well sealed what about mechanical heat recovery?
I looked at insulating the floors, used one of the calculators on one of the grant schemes. They estimated I could save about £20 a year by insulating the floors, pay back of 100 years!
Pretty sure an ASHP would be a bad idea in an older property, any retro fit wall insulation will be expensive, and unless you use something sustainable (which is the most expensive option) then a lot of the Cellotex type insulations are really bad environmentally.
One of the best things is to make sure and use the heating controls correctly, turn the temperature down as much as possible, using different temperatures for different times of the day. This can be simply using an analogue stat, you don't need to buy expensive controls.
I looked at insulating the floors, used one of the calculators on one of the grant schemes. They estimated I could save about £20 a year by insulating the floors, pay back of 100 years!
What I'm suggesting is that the calculators are bollocks.
Before I insulated there was air at floor level at around 18°C and roughly whatever the outside tempertature was outside the other side of 29mm of wood with gaps in some places. The first room I insulated under was noticeably warmer and could be walked around barefoot whereas the rest of the house still felt cold under foot.
We've done studies at work and the biggest difference you can make to an older property without spending loads on insulation is draught proofing.
People quickly become accustomed to differing comfort levels but draughts will have people turning up the thermostat.
An inverter from the solar panels into a hot water tank will reduce gas use.
Draught proof without insulating and you'll drown in condensation.
So I suspect the real benefit is not from the thermal effect of the insulation, but the removal of draughts.
In the course of my renovation I have overboarded the old floor boards with osb, then a floating engineered oak floor on 5mm fibre panels. That has made big differences to the temperature at floor level like you say but purely because I have remove the draught problem.
As above air movement makes people feel cold, one of the reasons positioning of radiators should be considered carefully.
That depends on where you are draught proofing and insulating and also at what level you started at.
Sure if your floors as poorly made as that then you'll notice. Difference.
Not sure it applies across the board.
My floor has nothing under it but then it's a 140mm suspended concrete floor with no gaps in.
The payback on retrofitting insulation makes no sense especially as the floors are not cold.
And everything in between.
Also maintenance of what's already there...making sure there is not years worth of dust collection behind the radiators, get the vacuum cleaner behind the fridge to make sure the fins are clear of dust and that is working as efficiently as possible. LED light bulbs through the home. Also saw this funky gadget on YouTube. It is a long thin panel of what looks like computer cooling fans, three or so in a block. It has spring loaded feet that secure it at the bottom of the radiator, either between the panels on a twin panel radiator or between the radiator and the wall. It detects when the radiator is on and the fans turn on and it provides forced convection for your radiators that will significantly improve the efficiency of the radiators and heat the room up more quickly and require less energy to maintain the temp. TRV valves on all the rads so you can not warm up rooms that are not used.
Think it is a series of lots of small things that add up to make a signficant difference before you start looking at chucking around lots of money on the bigger stuff that is unlikely to earn its way in any reasonable timescale. Save all of that for when things need replacement.
that will significantly improve the efficiency of the radiators and heat the room up more quickly and require less energy to maintain the temp
It will extract more heat from. The radiator as the fluid passes but it won't use any less energy. If your heating was set up properly (and many are not by folk fitting trvs DIY and not knowing what they are doing -you could decrease efficiency with these devices.
Bloody thermodynamics and physics getting in the way of snake oil products
It will warm up the room more quickly and distribute the heat more evenly avoiding hot spots around the rads with one side of the room being too hot and the other side freezing cold, and the CH system will shut down sooner once things get upto temperature and possibly mean you can reduce the duration your central heating is on. After that its all about insulation. If you have a leaky home then all you're doing is pumping heat through the leaky insulation but if the insulation is half decent and there are not drafts then it should help. Pointless doing anything until insulation has been maxed out and drafts fixed.
People have those spinney fans on top of their wood burning stoves to distribute heat better, that's not snake oil.
140mm suspended concrete floor with no gaps in
You realise that concrete has bugger all thermal resistance.
Concrete .14m - R= 0.0848 m2K/W
Wood .03m - R= 0.2308 m2K/W
So my 30mm of wood offers about three times the thermal resistance of your concrete floor.
Adding 100mm of insulation between the joists gets the whole floor of 30mm boards over 100mm of recycled polyester between deep floor joints to better than R = 2.8, or over thirty times that of your concrete floor.
Insulation and draught proofing/air tightness in combination with a sound stratergy for ventilation. You can get a door blower test done which will tell you just how bad it is and help locate the draught sources. The current thinking is actually not to go crazy on insulation as that can move the dew point to unwanted places in the structure, but to work on air tightness, maybe with a constant extract. Mvhr in an old house is going to be very tricky and may well be a step too far.
You realise that concrete has bugger all thermal resistance.
Do you realise my concrete floor resists drafts significantly better than your holey 29mm floor never mind how thick it might be in parts. ?
More my point(and bears it seems). Infact your maths suggests had you just fixed the holes you'd have had most of the benifit for minimal cost.
Concrete for internal floors and walls might work well actually as it acts as a very good thermal store so great at evening out heat energy through the house and sustaining it. That is after all how underfloor heating works. Granted you don't want it for external walls with no insulation, but internally might be a beneficial thing.
I did fix the gaps before insulating. 🙂 Have a little faith. 😉 It stopped the draughts but didn't make the floor feel any warmer, insulating did.
I fact I was so succesful in draught proofing I had to fit a roof vent and a vent in the room with the wood burner. The alternative would have been a heat recovery ventilation system but while were using the stove that would be complicated, and the stove does a good job of changing the air.
Concrete for internal floors and walls might work well actually
Concrete internal walls and floors create very efficient thermal bridges. If your concrete wall/floor connects to the outside structure you can refrigerate a whole house with them.
Have a look on the Net for thermal images with houses built on a concrete base, the base glows red.
https://www.schoeck.com/en-gb/structural-thermal-bridges
The unintended consequence of insulating older properties can be condensation - we're in that position in a rented house where the walls get damp and the result is mould growth.
I'd certainly consider looking at the floor construction and options. Our old house had an uninsulated concrete slab and it was cold in winter. There are some modern insulating materials that you can put over concrete / under floor coverings.
With Passivhaus and similar standards, the thinking is super-insulation and energy efficiency to the degree that you can heat the whole house with the equivalent of an electric towel rail.
I wouldn't look at ASHP in an older property without making sure everything else was super-insulated and air tight.
Tell her to look at Sunamp Ltd heat battery systems.
Dovebiker I take it your condensation is behind the insulation?
Any inside can't be caused by insulation, surely?...but by lack of ventilation.
Dovebiker I take it your condensation is behind the insulation?
It’s a converted steadying, stone construction with insulation and plasterboard. Cold walls and condensation with mould around the windows (UPVC double glazed) and anywhere with poor air circulation despite the heating being on near permanently. Doesn’t help we’re 1,000ft up exposed to weather. We’re out of here in 2-3 months anyway.
Feel your pain dovebiker. Solid walls are a PITA, they always seem to have cold spots. We're permanently wiping away at the worst bits to try and fight back the black stuff.
Pedal faster
People have those spinney fans on top of their wood burning stoves to distribute heat better, that’s not snake oil.
That's introducing convection to a source that is otherwise only radiant. Same effect as adding fins to a radiator panel.
Do you realise my concrete floor resists drafts significantly better than your holey 29mm floor never mind how thick it might be in parts. ?
More my point(and bears it seems). Infact your maths suggests had you just fixed the holes you’d have had most of the benifit for minimal cost.
Ed's right enough though, an insulated floor performs better than uninsulated regardless of the material used in construction. It is an utter shit of a job to do though, I only managed it by virtue of the fact my entire ground floor was removed. If I was doing it again I'd be doing it differently.
But yes, draughts produce serious heat losses, you really notice them more when the room has otherwise been sorted, been chasing a few down recently and it's made a noticable difference. Amazing what a can of expanding foam can do along the room edge.
Light her own farts to keep warm?
In years to come, mains gas will use hydrogen so will be a renewable way of heating. I think current boilers have to allow for up to 20% hydrogen so will be starting off as a blend of natural gas & hydrogen, then increasing to fully hydrogen. Detailed plans have been made but I don’t know the technical details.