Air Tightness Test - poor result

[Mike]

6 hours ago, mike2016 said:

this evening before the storm hits

When the storm hits is a great opportunity to detect the leaks - if the wind is strong you'll be able to detect if by feel. Just as useful as a second blower-door test!

[saveasteading]

1 hour ago, Benpointer said:

MVHR was number 1 on the list for our forthcoming self-build.

 

 

1 hour ago, Post and beam said:

not everything we buy needs to have a return on investment in cash terms

Interesting.

My payback assessment was for interest as I didn't believe some claims of it being just a few years.  If that was untrue, then what about the comfort claims?

It's mostly, though,  that I've never felt a building of mine was stuffy, or had any adverse client comment, even with a very large population and a good airtightness score.

 

I've spent my career in challenging newer fads.

e.g. I never installed wind turbines even when they were all the rage and scored BREeam points.

But was a user of SUDS.before it was fashionable.

Thus I need convincing. What made you put MVHR at the top? 

 

[Benpointer]

7 hours ago, saveasteading said:

 

 

Interesting.

My payback assessment was for interest as I didn't believe some claims of it being just a few years.  If that was untrue, then what about the comfort claims?

It's mostly, though,  that I've never felt a building of mine was stuffy, or had any adverse client comment, even with a very large population and a good airtightness score.

 

I've spent my career in challenging newer fads.

e.g. I never installed wind turbines even when they were all the rage and scored BREeam points.

But was a user of SUDS.before it was fashionable.

Thus I need convincing. What made you put MVHR at the top? 

 

 

Comfort, the freshness throughout the house all the time.  Go away for two weeks, come back and the house feels great.  We've never had that in any other house.  

 

Our current rented accommodation is by many standards a lovely house - well above average house price value - but it manages to be drafty and stuffy, at the same time, we even have mould in places. 

 

So yes, MVHR remains no. 1 on our list.

 

(I agree with you about fads though - 3D TVs say "Hi", and rain water harvesting for the toilets and washing machines will not be repeated by us again!)

[Mr Punter]

10 hours ago, ProDave said:

A near neighbour planned on DMEV and had pretty well installed that, but when his air test came in at less than 3 he was instructed by BC that full MVHR was required.

 

Surely it would be simpler just to make a few holes or leave the trickle vent open and retest.

[Roger440]

8 hours ago, saveasteading said:

 

 

Interesting.

My payback assessment was for interest as I didn't believe some claims of it being just a few years.  If that was untrue, then what about the comfort claims?

It's mostly, though,  that I've never felt a building of mine was stuffy, or had any adverse client comment, even with a very large population and a good airtightness score.

 

I've spent my career in challenging newer fads.

e.g. I never installed wind turbines even when they were all the rage and scored BREeam points.

But was a user of SUDS.before it was fashionable.

Thus I need convincing. What made you put MVHR at the top? 

 

 

Im all for challenging stuff.

 

Which is why i asked what you did instead. Once my house is sufficently air tight, then i will need to do something. However MVHR is certainly not my preferred option. Its complicated, difficult to retrofit, and needs maintenance. And costs power to run.  And makes noise. Some time ago someone posted "passive stack ventilation" for example. I liked that as it simple. Is it effective? No idea.

[ProDave]

1 hour ago, Mr Punter said:

 

Surely it would be simpler just to make a few holes or leave the trickle vent open and retest.

He didn't get the choice.  BC mandated mvhr must be fitted as the air test was <3.  I have seen it reported some people deliberately aim for just above 3 to avoid it.

 

Because the house was nearly finished he ended up fitting 2 small mvhr units, one for upstairs and one for downstairs to minimise the disruption to the building.

 

If you play with the figures in Jeremy's heat loss spread sheet, you will see once you get to a very good level of insulation, your heat loss through the walls is very low and ventilation heat loss starts to be a major proportion of total heat loss.  So your choice is something like DMEV which has no heat recovery, so all the expelled air is replaced by outside temperature air, or mvhr where perhaps 80% of the otherwise lost heat is recovered.

 

[Kelvin]

My focus was air tightness and to get as low as I could (0.44)  The consequence of that is you need MVHR. Therefore the payback was irrelevant. However the atmosphere in the house is very pleasant and fresh. The system is very quiet and low maintenance.  In Scotland you have to fit CO₂ monitors in the master bedroom. Background levels are around 450ppm although seen it much lower and it peaks at 750ppm over night with two people.

[saveasteading]

10 minutes ago, ProDave said:

your choice is something like DMEV which has no heat  loss

I don't understand. These are trickle fans expelling air, and in come draughts to replace it. Thus heat loss?

 

"Something like dmev " could be natural vents like wc fans and trickle vents.????

It's good to hear that my ' do nothing' principle is actually scientific and has a name.

I've got a degree including 'Building Science" so I just need some hokum explanation and the bco should accept it.

DNAVS. 

Decentralised Naturally aspirated ventilation system.

 

Seriously.  We always have high ceilings if we can contrive it. That helps reduce stuffyness.

[JamesP]

1 hour ago, Benpointer said:

 

Comfort, the freshness throughout the house all the time.  Go away for two weeks, come back and the house feels great.  We've never had that in any other house.  

 

Our current rented accommodation is by many standards a lovely house - well above average house price value - but it manages to be drafty and stuffy, at the same time, we even have mould in places. 

 

So yes, MVHR remains no. 1 on our list.

 

(I agree with you about fads though - 3D TVs say "Hi", and rain water harvesting for the toilets and washing machines will not be repeated by us again!)

Agree about the MVHR and rainwater harvesting. Tank again over filled yesterday due to blocked overflow. 

Edited 13 hours ago by JamesP

[Benpointer]

1 minute ago, saveasteading said:

I don't understand. These are trickle fans expelling air, and in come draughts to replace it. Thus heat loss?

 

"Something like dmev " could be natural vents like wc fans and trickle vents.????

It's good to hear that my ' do nothing' principle is actually scientific and has a name.

I've got a degree including 'Building Science" so I just need some hokum explanation and the bco should accept it.

DNAVS. 

Decentralised Naturally aspirated ventilation system.

 

Seriously.  We always have high ceilings if we can contrive it. That helps reduce stuffyness.

High ceilings reduce stuffiness; MVHR avoids it completely.

[Kelvin]

My wife was keen on rainwater harvesting. I wasn’t. It just seemed to add a degree of complexity and something else to worry about it and maintain. Had we built a house in  a dry part of the UK then maybe but not in Perthshire. I reckoned it would just be better if we reduced our water usage. 

[Benpointer]

5 minutes ago, JamesP said:

Agree about the MVHR and rainwater harvesting. Tank again overflowed yesterday due to blocked overflow. 

We probably will put in RWH as part of our SuDS, but for garden watering, not toilet-filling and clothes washing; grey toilets really suck.

[Kelvin]

There was an Eco Hub community centre in the village we used to live in that had rainwater harvesting. It worked well enough for them (in dry Cambridgeshire) but the grey toilets were a bit off putting. They did also have quite a lot of trouble with their plumbing too. 

[Thorfun]

15 hours ago, mike2016 said:

Have both pipes installed but closed with plastic bags and duct tape

i sealed ours up with airtight membrane and tape!

[ProDave]

33 minutes ago, saveasteading said:

I don't understand. These are trickle fans expelling air, and in come draughts to replace it. Thus heat loss?

Sorry, typo now corrected, I meant DMEV has no heat recovery.

[mike2016]

51 minutes ago, Thorfun said:

i sealed ours up with airtight membrane and tape!

The ducts are sealed where they penetrate the intello but they aren't connected to anything yet! The inside of the ducts were open to the outside so covered these up! Just was easier to chain drill the hole and fit the outside vents when I had scaffolding! 

 

11 hours ago, Mike said:

When the storm hits is a great opportunity to detect the leaks - if the wind is strong you'll be able to detect if by feel. Just as useful as a second blower-door test!

Thankfully in a rented room 20 minutes away while the storm blows through - the build is still standing so far via CCTV! If I find leaves and branches around the inside of the house I'll know where to check! 

 

13 hours ago, Nick Laslett said:

@mike2016 thank you for posting your results. Good luck with making any improvements. 
 

I’m sure there are some good posts here already about DIY air testing. It is a shame to pay twice for an air test if it can be avoided. But please keep us updated if you do get another test done. 
 

It would be good to know what else you could do, if you have already taped a membrane over the window interface?

 

 

 

Will be getting at least one more test done at the end. I'm setting up my own testing kit using a desk fan and smoke pen and ordered some more air tightness products to tackle likely weak points. The windows are nicely taped to the intello but somewhere in the reveal / below the window opening may be the issue. Once I find the source I can take a photo or two and post before and after. Then repeat per window. Just need the tools and I can apply the remedy! 

 

 

 

[JamesP]

29 minutes ago, Benpointer said:

We probably will put in RWH as part of our SuDS, but for garden watering, not toilet-filling and clothes washing; grey toilets really suck.

Same here, used for the garden and garage WC.

I emptied the tank last year and cleaned it thoroughly as even using filters and strainers debris still gets through. Also a few power cuts and pump troubles as well as digging out the overflow pipe to add more crates. Now will move overflow pipe past the crates and directly out.

[Thorfun]

14 minutes ago, mike2016 said:

The ducts are sealed where they penetrate the intello but they aren't connected to anything yet! The inside of the docts were open to the outside so covered these up! Just was easier to chain drill the hole and fit the outside vents when I had scaffolding! 

that's exactly what i mean and we did. so the exhaust and intake external holes were sealed using airtight membrane rather than a plastic bag. i would've through that small amounts of air might penetrate a plastic bag? also potentially prone to ripping? i just didn't want any potential leakage during the test is all.

[saveasteading]

It has become a discussion about rainwater. Can someone split this out?

I am for and against. Circumstances.

I've still lots to learn from advocates about mvhr which I've never used. 

And experience of RwH if anyone  interested.

[Nickfromwales]

16 hours ago, saveasteading said:

You have fans in the wc and kitchen...a 110mm hole direct to outside.  We all do. But they suck the air from draghy windows/ under doors which you have nearly sealed. Relax.

Only in a house without MVHR   

[Kelvin]

Are there any super airtight houses that don’t have MVHR and ventilate via other means? 

[Nickfromwales]

13 hours ago, Benpointer said:

We probably will put in RWH as part of our SuDS, but for garden watering, not toilet-filling and clothes washing; grey toilets really suck.

Yup. Seen it (and have installed it under orders) and I wouldn’t ever entertain bringing such grotty water into my toilets……and never in a million years into my washing machine. WC cisterns go black, even with 3-state filtration, so you’d need to factor in a good UV sterilisation setup to get me to even fill a toilet with it. 
Fine for watering the garden, but when you need to water the garden the tanks bone dry because there’s no chuffing rain….and when rains abundant you don’t need to water the garden.🤷‍♂️🤦‍♂️. Go figure.

Total waste of time and money afaic, and I’d recommend using that for PV / battery or just beer without a second thought. 
Oh, and as soon as the pump snuffs it your payback year goes to triple digits, and then the second pump will eventually need to be replaced, and so on. Judy cheaper to buy the water when you actually do the maths, after buying the system, installing it, and the constant maintenance & repairs.

Oh, and in the summer when the rain buggers off it’s then electro-mechanically filled by the cold mains lol. Then you pay to pump it into the toilets. 
 

“Seriously?”  🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️

[Nickfromwales]

8 minutes ago, Kelvin said:

Are there any super airtight houses that don’t have MVHR and ventilate via other means? 

That’s like asking how can I go for loads of cost and effort for nothing?

Why build airtight then fill it with natural or mechanical ventilation to defeat the efforts and increase the heating requirements….

[Nickfromwales]

23 minutes ago, saveasteading said:

It has become a discussion about rainwater. Can someone split this out?

My bad, sorry 

[Nickfromwales]

I used to use smoke pellets and matches to test gas fires etc, so these may be good for DIY blower testing. Non toxic. 
 

https://www.toolstation.com/arctic-hayes-smoke-pellets/p73709?store=W8&utm_source=googleshopping&utm_medium=feed&utm_campaign=googleshoppingfeed&gad_source=1&gbraid=0AAAAAD-vLcW28_oiBQC-P6TC6ImMppCpz&gclid=CjwKCAiAkc28BhB0EiwAM001TRkm8DqzJjYkdSY0aHk5-WsPiZPc7NWyw9j4RvGd5BcssGMWnV9-rhoCrW0QAvD_BwE