MVHR is Largely Bogus

[SteamyTea]

In Our Time

Mercantilism

 

Worth a listen.

 

As is Start the Week, which is on right now.

[SimonD]

9 hours ago, Gus Potter said:

can we pinch ideas

 

9 hours ago, Gus Potter said:

Yes there is a bit in the building regs about this but if you think about it.. it's a controlable chimney. They do it in Spain for example just here BC don't help. 

 

Exactly, I'm an outlier in that I designed a house for natural ventilation and have been called a heretic even by a number of people in the green building field because apparently I'm destroying the planet by wasting heat.....

 

For me all it took was to look at the inherent fallabilities of MVHR technology together with reading a lot of research on the technology too. Then I designed the fabric of the house in such a way that it would naturally reduce internal RH by as much as 25% (most ventilation system work load is required to remove moisture) and design a natural ventilation system to work with the local microclimate and house. I have not a fan in the house and we have no problems with condensation, no drafts or anything like that. It's lovely and warm when it's cold outside, so much so it's maintaining its indoor temperature with only 1/3 of the designed number of radiators and for when it gets hot I have a ventilation stack.

 

Unfortunately, Building Regs have recently made this more difficult as they're trying to force MVHR by default, probably because research findings show that the majority of newbuild houses do not comply with the basic natural ventilation requirements. If you now want natural ventilation you've got to demonstrate specialist design.

 

The thing is that proper natural ventilation does require a different approach to the fabric and some thought at the design phase - given how we approach much of house building in the UK, I wonder whether right now it's simply a stretch too far?

[Kelvin]

10 hours ago, Gus Potter said:

 

 

 

Anyway.. kids need fresh air not filtered air.. just think about it if you are a parent.

 

 

 

 

 

 

On this point. MVHR is fresh air filtered from the normal contaminants that is in the fresh air all around so I don’t quite understand this point. 
 

I too worked at Torness during its commissioning as a systems tester for the Ferranti Argus 700 control systems. 

[Iceverge]

@SimonD what specialist technique did you employ to ensure natural venting was adequate? Do you have any monitoring of the air quality as this is too often pitiful in non mechanical ventilation systems. 

 

I drew our house so that every bedroom, living room and kitchen has 2 operable windows (T&T) on walls facing different direction to ensure good cross ventilation. Similarly the upstairs hallway.

 

However we did employ MVHR. I dismantled it at the weekend to clean the exhaust fans and heat exchanger as it was growing some kind of mold on the exhaust side of the unit. I think due to not having the unit perfectly level on the wall bracket which was causing the condensate level to be too high. 

 

Time will tell if that corrects it. 

 

As for the complexity involved, I was surprised by how simple it was really. 2 fans, made in Germany and a digital speed controller essentially. To the point it would be pretty easy with some OSB, foam and off the shelf fans and a heat exchanger to make one yourself. 

 

 

 

[SteamyTea]

46 minutes ago, SimonD said:

Exactly, I'm an outlier in that I designed a house for natural ventilation and have been called a heretic even by a number of people in the green building field because apparently I'm destroying the planet by wasting heat

There are many way to skin a cat.

 

I made my own MVHR as a project, had a thermal recovery of about 80%. The two fans where very inefficient as they where just Manrose bathroom extractor fans. But it worked.

It did get me thinking that, on a new build, making walls and ceilings the heat exchanger would be pretty simple, lots of surface area, which is the main thing that is needed.

Would not be hard to fit in a heating/cooling system as well, that is just pipes.

[Iceverge]

On the design of MVHR units I have a couple of suggestions to the manafactuer's.

 

I think both fans should be kept at the warm side of the heat exchanger. This would prevent them from ever getting cold and developing mould on the blades which kills pumping efficiency. 

 

The unit should be more easily serviceable. Mine required 10 screws and the front of the unit to be taken off in order to access the heat exchanger and fans. 

 

There's no reason this couldn't be done with over center clips or similar to make a 1hr job a 5 minute job. 

 

A quick wipe down with a microfiber cloth and vacuum of dust etc could be done by anyone then, not a trained professional etc etc.

 

If maintenance isn't easy then it doesn't get done. 

 

 

 

 

[jack]

12 minutes ago, Iceverge said:

On the design of MVHR units I have a couple of suggestions to the manafactuer's.

 

I think both fans should be kept at the warm side of the heat exchanger. This would prevent them from ever getting cold and developing mould on the blades which kills pumping efficiency. 

 

The unit should be more easily serviceable. Mine required 10 screws and the front of the unit to be taken off in order to access the heat exchanger and fans. 

 

There's no reason this couldn't be done with over center clips or similar to make a 1hr job a 5 minute job. 

 

A quick wipe down with a microfiber cloth and vacuum of dust etc could be done by anyone then, not a trained professional etc etc.

 

If maintenance isn't easy then it doesn't get done.

 

Couldn't agree more with this. It's difficult to access the surfaces of the fans on our unit. Partly that's due to where/how we've installed it, but easily removable components would make me far more likely to stay on top of keeping the unit clean.

 

I've noticed our making a bit more noise over the last few months (7.5 years after installation) and suspect I might have a bearing on the way out. I'm not looking forward to that job!

[Onoff]

1 hour ago, SteamyTea said:

I made my own MVHR as a project

 

There's always a smart ar5e! 🤣

[SteamyTea]

1 hour ago, Onoff said:

 

There's always a smart ar5e

Yes, and mine smarts more than most after last nights trip to the theatre to see a gender neutral version of The Addams Family.

 

(was not gender neutral at all, some wore skirts and dresses, but they all had makeup on. We have long winters down here, but it keeps us off the dog shit covered streets)

[saveasteading]

13 hours ago, Gus Potter said:

To finish.. I'll appeal to your wallet

I'd say pragmatic rather than downbeat.

Midnight with a glass of wine brings out the inner feelings.

 

The wallet thing is key.

Most people will buy what they want, if it is cheap enough, and it will be from China. 

If wool insulation was the same cost as glass insulation then we woild use it as standard. Farmers lose money each fleece so they are very very cheap. A reborn wool marketing board could turn this around.

If nothing burnable was buried or exported, but used for power then clay bricks could replace concrete and eps. 

And 100% recycling plastic into  whatever.

Subsidised house improvements will quickly repay the investment.

And so on.

Put Gus in charge and i will help, and it could all be sorted....BUT would the government allow big oil and other cosy relationships to suffer?

 

Most of all perhaps, who in govermnent would understand anything slightly technical...a different mindset.

[SteamyTea]

55 minutes ago, saveasteading said:

A reborn wool marketing board could turn this around.

A fleece is around 2.5 kg and there are about 15 million flock sheep in the UK.

So;

2.5 [kg] 15,000,000 [fleeces] = 37,500 tonnes a year.

I have no idea how much is put in a house, but at 0.15kg.m^-1 that would be 250,000 m².

 

Taking a relatively standard detached house, say 10 m by 8m, then the insulated area will be ~200 m².

 

250,000 / 200 = 1250 houses.

 

In England, from the start of October 2021 to the end of September 2022, 173,220 houses were completed.

So;

 

1250 / 173220 * 100 = 0.72% could be insulated with fleece, if all the fleece was used.

 

Now, if you want to farm sheep sustainably, you need to keep the numbers per hectare down.  With some manual input (which is just importing food from somewhere else) you will be lucky to farm at 10 sheep per hectare.

 

So;

15,000,000 [sheep] / 10 [sheep per hectare] = 1,500,000 hectares. Or 15,000 km².

 

England has a land area of 130,279 km².

 

So

 

15000 [land area for sheep] / 130279 [England land area] * 1000 = 11.5% of the England's land.

 

Now it is unfair to just poo poo an idea without offering an alternative.

My alternative would be to replace sheep with PV, which produces about 1 GWh/hectare. year.

 

So

 

15000 [hectares] x 1 [GWh/hectare) = 15000 GWh/year.  That is 15000000000 kWh, or 57,700 kWh for each of the UKs (not just England) houses, a year.

 

I say dress our sheep up and swap them for Chinese PV modules.

 

Edited March 20, 2023 by SteamyTea

[JohnMo]

There about 40 sheep in the field next to me (if that helps), but most are lambs so not much use for shearing yet. 

 

Farmer has to pay to have them sheared and then also has to pay to get rid of the fleeces.

[SteamyTea]

4 minutes ago, JohnMo said:

There about 40 sheep in the field next to me (if that helps),

How big is the field, and how often are they given supplementary nourishment?

5 minutes ago, JohnMo said:

most are lambs

Probably not for flock then.

I had a fair amount of one in last night's Donner Kebab.

 

There was this Scottish guy called Hamish.

He had a bad reputation, so I asked him why.

His reply was as follows.

"You see that house, I built that, do they call me Hamish the builder, no.

See that fishing boat, I made that, do they call me Hamish the fisherman, no.

But one sheep...."

[JohnMo]

2 minutes ago, SteamyTea said:

How big is the field, and how often are they given supplementary nourishment

They seem to have additional nourishment all through the winter and plenty of neeps.  The field is about 200m x 250m could be bigger.  They have another bigger field they get rotations in also.

[Onoff]

3 hours ago, SteamyTea said:

A fleece is around 2.5 kg and there are about 15 million flock sheep in the UK.

So;

2.5 [kg] 15,000,000 [fleeces] = 37,500 tonnes a year.

I have no idea how much is put in a house, but at 0.15kg.m^-1 that would be 250,000 m².

 

Taking a relatively standard detached house, say 10 m by 8m, then the insulated area will be ~200 m².

 

250,000 / 200 = 1250 houses.

 

In England, from the start of October 2021 to the end of September 2022, 173,220 houses were completed.

So;

 

1250 / 173220 * 100 = 0.72% could be insulated with fleece, if all the fleece was used.

 

Now, if you want to farm sheep sustainably, you need to keep the numbers per hectare down.  With some manual input (which is just importing food from somewhere else) you will be lucky to farm at 10 sheep per hectare.

 

So;

15,000,000 [sheep] / 10 [sheep per hectare] = 1,500,000 hectares. Or 15,000 km².

 

England has a land area of 130,279 km².

 

So

 

15000 [land area for sheep] / 130279 [England land area] * 1000 = 11.5% of the England's land.

 

Now it is unfair to just poo poo an idea without offering an alternative.

My alternative would be to replace sheep with PV, which produces about 1 GWh/hectare. year.

 

So

 

15000 [hectares] x 1 [GWh/hectare) = 15000 GWh/year.  That is 15000000000 kWh, or 57,700 kWh for each of the UKs (not just England) houses, a year.

 

I say dress our sheep up and swap them for Chinese PV modules.

 

 

Given the trend for that "clean look"  would you care to do the math on "that" as a source of insulation? 

[SteamyTea]

11 minutes ago, Onoff said:

Given the trend for that "clean look"

Have I missed some new trend, we are just entering the early 2000 down here.

[SteamyTea]

17 minutes ago, JohnMo said:

The field is about 200m x 250m could be bigger

5 hectares then.

8 woolies to the hectare.

Edited March 20, 2023 by SteamyTea

[Roger440]

22 hours ago, Gus Potter said:

Good thread.

 

But for the younger members from an "old crusty".. may save you money.. choice is yours.

 

My thoughts and a bit of back ground. I worked at Torness Nuclear power station, and have designed stuff for the decomissioning of Bradwell Nuclear Station so apreciate the decomissing costs. Mostly now I do domestic stuff.. Part of my Masters was to do with the energy supply in the UK.. I started out as a local builder.. so did not go into Uni right away..

 

I also had a spell at designing farm buldings with 40 kW pv when the grants were good. Yes I was right into it.. how the grants worked and so on.

 

Have to say one at least went on fire as the invertor did not do what was written on the tin. Lucky for me I was not in the firing line.. but it burnt well and no one got hurt.

 

Yes, I'm near sixty but I still practice so have not quite turned into a fossil... and can't see me going woke any time soon.

 

Anyway my thoughts are.. Marcro and from an SE / designer point of view looking to the future.

 

If you are an environmentalist and into PV.. or any other home automation just to be blunt you have a living in a bubble. For the following macro reasons not least:

 

1/ China are becoming dominant to the extent that they are going to influence what happens in fifteen/ twenty say years time, unless they invade Taiwan.. then we will have much more to worry about.

 

2/ The stuff that we rely upon comes from mostly China and the "belt and braces"  and most importantly hegemony that they have fostered. I also grew up in Africa and follow how the Chinese  have weaved their way in that continent.. and some think the British Colonials were bad!

 

3/ All this stuff we are introducing.. electronics.. EV cars requires for example, mining and invites destruction of the environment..

 

4/ Have you thought about getting replacement parts and how much these are going to be in say 10 - 20 years time? Remember washing machines don't last that long.. you MHVR is intrinsic to the house so should be able to preform in the long term. Do you honestly expect that you MHVR is going to last the design life of the house? You'll be lucky if it works for five years and each ear yoy need to change the filters..

 

 

 

Look folks you have to wake up and realise that while we are trying to save every extra penny in the UK other countries are shafting the environent and the global eco system we need to produce the "air we all breathe"

 

You also need to recognise that you are buying filters, the running cost.. and inherant redundancy.

 

Get your head round this. If you think strategically...

 

The best thing we can do is to try and adapt our building systems to use the materials we have in the UK. We have lots of clay.. if we supported our Farmers and brick industry we could have  bricks and wool.. good for insulation in the right combination. Also all locally sourced and provides jobs... I could list more but we have in the uk many of the things we need to protect the environment without haveing to ship in stuff.

 

Look there is word that in the south of the UK they is Lithium for batteries.. in Scotland we have the wind to charge them up.

 

Just maybe we could start to think.. hey... see in the south of the UK our houses are getting a bit to hot in the summer.. can we pinch ideas from Adobe houses that rely upon passive stack ventilation. Yes there is a bit in the building regs about this but if you think about it.. it's a controlable chimney. They do it in Spain for example just here BC don't help. 

 

Anyway.. kids need fresh air not filtered air.. just think about it if you are a parent.

 

Yes you may think I'm off the mark here.. but see in ten years time when you can't find replacement parts for you MHVR and home automation other than from China.  I'll get the last laugh.. if I'm still here. If not well you made you own bed.

 

I have a house with UF and  some nice bells and whistles.. but these come at a cost.. there is not a couple of weks that goes by when something does no break down.. You'll end up saying.. the house was great for the first month.. but there are loads of things not working and it is getting on my tits.

 

When I go to see a Client I point out the good bits and the bad..

 

For example just this weekend two dimmer light units have failed out of about 16.. and that is in the first 18 months of installation .. and they have to come from China. 

 

I can fix this myself but what if you are not OK with diving into electrics.. how much is the spark going to cost you?

 

To finish.. I'll appeal to your wallet. Do you think that having MHVR is a good or bad selling point? Can you demontrate to a buyer that it all works, what value is a Surveyor going to attach to it.. is it like a dodgy gas boiler... at least a gas boiler has a Gas safety certificate .. your MHVR just has.. cowboy written all over it!

 

 

 

 

 

 

Im with you on this.

 

I like simple. The simpler the better.

 

I see people on here talking home automation etc. Why? I just dont get it. More shit to go wrong. And it will.

 

Accepted that some on here just like tinkering. And have the ability.

 

I dont. It will just end up costing a bunch of money.

 

Passive stack ventilation. Definitely. Plus its truly silent as a bonus.

 

 

[Roger440]

9 hours ago, saveasteading said:

I'd say pragmatic rather than downbeat.

Midnight with a glass of wine brings out the inner feelings.

 

The wallet thing is key.

Most people will buy what they want, if it is cheap enough, and it will be from China. 

If wool insulation was the same cost as glass insulation then we woild use it as standard. Farmers lose money each fleece so they are very very cheap. A reborn wool marketing board could turn this around.

If nothing burnable was buried or exported, but used for power then clay bricks could replace concrete and eps. 

And 100% recycling plastic into  whatever.

Subsidised house improvements will quickly repay the investment.

And so on.

Put Gus in charge and i will help, and it could all be sorted....BUT would the government allow big oil and other cosy relationships to suffer?

 

Most of all perhaps, who in govermnent would understand anything slightly technical...a different mindset.

 

Sadly the wool thing i doubt will ever fly.

 

I looked at this for my barn. I could get the fleeces for free. Its still doesnt stack up to get to a usuable product. Even if i did it all myself.

 

Cheaper to buy a roll of rockwool.

 

[Roger440]

13 hours ago, SimonD said:

 

 

Exactly, I'm an outlier in that I designed a house for natural ventilation and have been called a heretic even by a number of people in the green building field because apparently I'm destroying the planet by wasting heat.....

 

For me all it took was to look at the inherent fallabilities of MVHR technology together with reading a lot of research on the technology too. Then I designed the fabric of the house in such a way that it would naturally reduce internal RH by as much as 25% (most ventilation system work load is required to remove moisture) and design a natural ventilation system to work with the local microclimate and house. I have not a fan in the house and we have no problems with condensation, no drafts or anything like that. It's lovely and warm when it's cold outside, so much so it's maintaining its indoor temperature with only 1/3 of the designed number of radiators and for when it gets hot I have a ventilation stack.

 

Unfortunately, Building Regs have recently made this more difficult as they're trying to force MVHR by default, probably because research findings show that the majority of newbuild houses do not comply with the basic natural ventilation requirements. If you now want natural ventilation you've got to demonstrate specialist design.

 

The thing is that proper natural ventilation does require a different approach to the fabric and some thought at the design phase - given how we approach much of house building in the UK, I wonder whether right now it's simply a stretch too far?

 

Please post up how you go. 

 

As for building regs, they can bugger off. Just not interested. Solves the specialist design requirement!

 

As ever, government mandating a solution rather than an outcome. 

[Kelvin]

The wool thing is interesting. We were driving to Lossiemouth about 18 months ago listening to the wireless. The news came on and there was a report about wool and how it’s valueless and often being buried in the ground. My other half asked why aren’t we stuffing the house with that? I said cost. So she went on a crusade and did loads of research but it still boiled down to cost. 

[Roger440]

5 minutes ago, Kelvin said:

The wool thing is interesting. We were driving to Lossiemouth about 18 months ago listening to the wireless. The news came on and there was a report about wool and how it’s valueless and often being buried in the ground. My other half asked why aren’t we stuffing the house with that? I said cost. So she went on a crusade and did loads of research but it still boiled down to cost. 

 

Exactly.

 

That said, if we produced wool insulation in the quantity of rockwool, i suspect there wouldnt be much if anything in it.

 

But who is going to take the punt up against the majors with vested interests?

[Iceverge]

I doubt there is ever an economic case for wool as a house insulant. Theres too many steps involved for something that can be done well with other materials. 

 

It's a shame more people don't realise how bloody excellent it is as clothing however. 

Wool socks and wool jumpers are tremendous. Always warm, never sweaty. I wear them every day.

 

Something like hemp would be far more economic as an insulant I suspect. It would sequester loads of carbon too and can be grown really easily. 

 

Unfortunately processing facilities are tough to find. 

Edited March 20, 2023 by Iceverge

[saveasteading]

9 hours ago, SteamyTea said:

I have no idea how much is put in a house, but at 0.15kg.m^-1 that would be 250,000 m².

Good work. I would have guessed it went much further but that is the point of challenging and checking isn't it.

 

I make it 3 x that by mental arithmetic, so if the rest is about right, 2% of the new houses. Rather than bury, that has to be worth while.

I checked out the possibility of buying local fleeces but the cleaning is the problem. fleeces are messy and tangled and dense. But that is where organised technology should come in. Using green energy and no caustic solutions of course.

[Onoff]

6 hours ago, Iceverge said:

as an insulant

 

Mycelium?