Self build house - is MVHR worth cost?

[Wadrian]

Really interested to hear from anyone who has installed MVHR on a self build in last couple of years. I am building 250sq m house. What costs am looking at for system and also what has been people experience of it - would they install it again? 

[Redbeard]

I haven't - sorry - but what standard of air-tightness are you going for? The answer may answer your Q.

[Bramco]

Yes  it's essential in a house which is nearly airtight - and if you are self building and don't intend to make things nearly airtight, then you've got to be daft because all of your heat will disappear into the environment through the draughts.  But you need either a good builder, or a lot of patience to get the airtightness. And a lot of attention to details - window frames should not have vents etc.

 

Air quality internally should be much better as well as the air entering the house has been filtered.

 

[IanR]

MVHR doesn't bring benefit in itself, but it facilitates air tightness better than 3m³/m².h@50Pa.

Good air tightness brings comfort and energy cost benefits and allows you to then filter the required ventilation to remove duct and pollen.

For air tightness greater than 3m³/m².h@50Pa you must have whole house mechanical ventilation.

[JohnMo]

6 minutes ago, IanR said:

whole house mechanical ventilation

Balanced - supply and extract.

[newbuild upnorth]

ive used BPC to design and supply recently, cheapest by a fair margin and very easy to deal with. ive also gone for the middle of the road system as I dont believe the pay back is worth the cost if im honest.

I wouldn't have it if I could avoid it but thats my personal opinion and not really a popular opinion!

 

I went for 2 units instead of one big unit, huge saving having 2 smaller units rather than the one big unit but this was also influenced by the kit design and running all back to one unit would have been a massive pain.

the companies I engaged were split 50 / 50 on one unit or two so its nothing radical.

[Bonner]

One of the best things I did, self installed in a similar sized house for less than £2k. Very simple unit, no sensors, rigid plastic ducting. Wouldn’t want to live in a house without it.

[JohnMo]

1 hour ago, Wadrian said:

Really interested to hear from anyone who has installed MVHR on a self build in last couple of years. I am building 250sq m house. What costs am looking at for system and also what has been people experience of it - would they install 

it again? 

My first quotes were circa £10k - which is just bonkers. Ended up installing two units (good for my layout) total cost circa £2k for self installation and professional commissioning.

 

Compared to houses with piss poor ventilation, which is most, it's ace. More like being outside than inside.

 

If you don't have an airtight strategy (you really should have one), I would do dMEV or MEV with humidity control and most importantly humidity activated trickle vents. This is the lowest install cost, least ongoing maintenance that gives decent ventilation with undue ventilation heat loss.

Edited Tuesday at 12:18 by JohnMo

[Nick Laslett]

@Wadrian, here are some useful links to previous threads discussing this topic. 
 

This is the best anti-MVHR thread. *Edit: Just had a re-read of this thread and it brings back many memories from the forum. 
 

 

Here is a good discussion from 2017. 
 

 

This thread from 2021 is the classic retrospective question. 
 

 

This is a more recent version of the same question. 
 

 

When I first joined the forum, I was very resistant to the MVHR concept. But I eventually saw the light. MVHR does add a significant cost to the build. You also need to design it into the fabric of the building as early as possible. 
 

You can DIY install an MVHR system and there is a lot info here to help. If you look at a lot of the classic BuildHub threads on MVHR, ASHP, Hot Water Manifold, Fancoils, etc you will realise that an optimum build possibly has a plant room in the centre of the house to hold all this kit. So sometimes I feel that the most pertinent question is, “how would you tackle the services and plant room aspects of your build differently, now that you understand all the trade offs?”

 

Edited Tuesday at 12:44 by Nick Laslett

[Iceverge]

Yes we have it. 

 

Cost about €2500 in 2020 to DIY. 

 

Running costs are about €40/year on electricity and the same again in filters. About 2hrs labour per year I would say on average for cleaning and servicing the unit. I DIY it and my unit is very accessible, not tucked away in the corner of some attic

 

On a new build on £££ alone won't stack up against dMEV or DCV unless you use the energy savings to omit the central heating from the budget on day 1 like we did.

 

I would do it again for the comfort and quietness. I wouldn't recommend it to anyone who was unlikely to spend the time or money on correct maintenance. 

 

For them a few Greenwood dMEV fans and humidity sensitive wall vents would be a far better bet. 

 

 

 

 

[MikeSharp01]

Our self install is running at about £3.5K for bits, 150m² 2 bed home. Not switched it on yet and I am sure I have made it more complicated than it needs to be, will see how it goes in a couple of months when we turn it on.

[Dreadnaught]

As with @MikeSharp01, for my self-build I have a Ubbink Vigor W325 (same as the Brink Flair 325) with Ubbink ducting for a total cost of about £3.5k all in. I installed all the ducting and the unit myself, solo.

 

I'm at first fix but the MVHR has been running since May 2024.

 

Wouldn't be without it. One of the best parts of my build. And MVHR will be top of my wish list for my next self-build.

Edited Tuesday at 17:08 by Dreadnaught

[MikeSharp01]

1 hour ago, Dreadnaught said:

m at first fix but the MVHR has been running since May 2024.

How are you dealing with the dust getting into the system.

[Dreadnaught]

1 hour ago, MikeSharp01 said:

How are you dealing with the dust getting into the system.

 

Fortunately my house isn't very dusty and haven't found it a problem - except perhaps when plastering - and I just turn the system off then (and open the windows). I have been monitoring the filter-from-the-dwelling.

[Nickfromwales]

9 hours ago, IanR said:

MVHR doesn't bring benefit in itself

…erm?

 

Beside managing humidity, providing fresh tempered air to all habitable spaces, and recovering heat that’s normally lost to the clouds.

[Gus Potter]

10 hours ago, Wadrian said:

Really interested to hear from anyone who has installed MVHR on a self build in last couple of years. I am building 250sq m house. What costs am looking at for system and also what has been people experience of it - would they install it again? 

Good question.

 

There is a lot of good technical comment from previous posters. 

 

11 hours ago, Wadrian said:

would they install it again? 

MVHR is well proven technology if you design it right, build in a bit of spare capacity so you can sell the house on without copmpromising the value and live in a certain way.

 

So in that context I'll paint you a diferent picture.

 

Now I am a past self builder, site was in the country, like waaay out in the sticks. But round about me were other young  couples that were also that were doing the same. 

 

Most wanted a house that was large enough to fill with kids.

 

Most of us were in our 30's or a bit younger (but there was also a cohort of retiring folk who really got behind the ethos and they also wanted chickens and plenty fresh air.. like open windows and doors) and wanted to send their kids to the good local school, get chickens! And sure enough it all happend. Good teachers moved to the local school and it thrived. 

 

But it did not stop at chickens! Then there were sheep, goats, more kids, the dads got involved in the local scouts, the local pheasant shoot, (they learnt to shoot as the foxes were eating their chickens) their houses became a hive of activity.. the doors were open and shut from morning to night, the new kids got sick at first when they moved to the country so windows were open / shut .. 

 

Take a step back @Wadrian and review again! What function you want your house to perform. You are starting, it seems, to think about a bit of technical design..you'll get loads of info on BH so always review, it's Ok to change your mind as you go and learn more. 

 

If it just a house for say two of you that are in eh "later years like balding me" or a mental family with a country feel, you get to smell  / topuch what is happening in the outside environment, If mental then MVHR is maybe not the best option in the first place!

 

Personally as a designer, SE, ex building contractor with 40 years experience my personal  horror is to live in a sealed box! It looks great on paper but few years down the road it makes no commercial sense to me in the self build market ( it will break down so if you can avoid installing it in the first place? ) and is probably bad for your kids. 

 

 

 

 

 

 

[Crofter]

On my very small (43m² internal) house I spent about £700 on the smallest MVHR I could find. It's just got one supply, in the open plan kitchen/diner, and one extract, in the bathroom. 

 

It's absolutely been worth it. Even when the house is empty for a few days and the temperature drops, it remains completely free of damp, and feels very comfortable and pleasant. There's never any dust anywhere. Couldn't imagine building a new house and not fitting MVHR.

[Mike]

I spent >€4K on my apartment (+VAT), but that includes following my own advice and installing a PassivHaus certified Zehnder unit (with per-heater due to cold winter temperatures) and hiring some guys to abseil down the side of the building to core-drill through 400mm of stone for the air intake and exhaust. Apart from them screwing the external vents in place, it's self-installed. If you're wondering, I can vacuum the vents from the windows.

 

The new electrical installation is incomplete so It's not yet operational, but it's installed for several reasons. The apartment will be pretty airtight so it provides the necessary ventilation; I'm in an urban setting so using it to filter the air and avoid noise via trickle vents / open windows is a very big plus; it's essential to reduce humidity due to having a tricky unventilated insulated ceiling; adding an evaporative cooler to it (another €1K) is the only way I could provide some summer cooling; it also provides heat recovery during the heating season.

 

[IanR]

14 hours ago, Nickfromwales said:

…erm?

 

Beside managing humidity, providing fresh tempered air to all habitable spaces, and recovering heat that’s normally lost to the clouds.

But, a house that has uncontrolled (natural) ventilation above 3m³/m².h@50Pa is deemed to have sufficient ventilation (when combined with trickle vents and wet room extractors). That leakage is unfiltered and without an option to recover energy from.  Any additional ventilation brought in by an MVHR system is unrequired, so while it may be filtered and have 85% of the energy recovered from it, it is additional, unrequired ventilation and therefore adds to the energy losses and dust/pollen/pollutants (that make it through the filters) within the house.

It's having better air tightness that stops the uncontrolled leakage of warm air and ingress of dust/pollen etc. and then provides the option of heat recovery and filtration.

[jack]

On 12/08/2025 at 12:04, Wadrian said:

Really interested to hear from anyone who has installed MVHR on a self build in last couple of years. I am building 250sq m house. What costs am looking at for system and also what has been people experience of it - would they install it again? 

 

I can't help you with recent costs, but we've lived in a house with MVHR for (unbelievably!) 10 years this Christmas. There's no way I'd ever consider building a house without it.

 

There's something magical about having fresh, warm air throughout the house in winter. I don't really think about it any more until I encounter stuffy air in other peoples' houses in miserable winter weather.

 

If you're even vaguely handy, it's one of the most straightforward things you can self-install, and you'll save a lot of money compared with having professionals do it.

 

We installed everything ourselves except the drain and the power supply wiring. I did most of it myself over perhaps three easy days, with my wife helping me pull ducts through the easi-joists.

 

There are arguments about the costs/benefits of running an MVHR system. You have a permament load of something like 10-40 W, depending on how big the unit is and what flow rate you run, which is a a few tens of quid a year in electricity. You need to regularly clean and occasionally replace filters, which could be another few tens of quid a year depending on brand, how often you replace them, whether you're willing to make your own from cheap filter media, etc. I'd be surprised if the reduced cost of heating due to the heat recovery offered by MVHR didn't save us more than the cost of its power consumption and filter maintenance.

That said, it's a big upfront cost. If it last 10 years, it's something like £300-400 a year if you install it yourself. I doubt MVHR saves us anything like that amount on our heating bills.

That said, I'm coming up to 10 years with the same unit. It's becoming apparent that the motors need new bearings, but otherwise the unit shows no sign of degradation.

 

Hope that helps.

[SteamyTea]

6 hours ago, IanR said:

But, a house that has uncontrolled (natural) ventilation above 3m³/m².h@50Pa is deemed to have sufficient ventilation

To add to this.

As the ventilation is uncontrolled, who knows where the warm, damp, internal air is leaking out to.

If the leaks where dispersed uniformly, and not near any timbers, then maybe condensation would not be a problem.

But I bet even the worst builders can't make every square metre of exposed wall equally as bad.

Forced, or a better term is controlled, ventilation gets around this problem.

 

[Wadrian]

Thank you to the individuals who took the time to respond to my request. As always it is do good to hear of people individual experience. MVHR seems a really good system to install and relatively inexperience if DIY install. 

[joth]

According to the status page ours is reducing our heating demand by about 2000 MWh per year. So something like £50-400 per year savings, depending how much you pay for heating energy.

But hard to place a figure on the air quality, cleanliness and health benefits. That's the primary reason I installed it, rather than for a bottom line cost saving 

[SteamyTea]

1 hour ago, joth said:

According to the status page ours is reducing our heating demand by about 2000 MWh per year

Compared to what though.

 

May sound an odd response  but you would save the running costs by switching your MVHR off and the building airtightness would remain unchanged (may get a bit smelly indoors).

Doing that is not the same as comparing a house with an ACH figure below 1 with MVHR and a non MVHR house with an ACH figure of 7.

Volume of the house makes a difference as well.

[Iceverge]

On 13/08/2025 at 00:50, Gus Potter said:

Personally as a designer, SE, ex building contractor with 40 years experience my personal  horror is to live in a sealed box!

 

The house i grew up in winter had 2 modes. 

 

1. Howling winds blowing through the cracks and freezing cold. 

 

2. Stuffy as hell and damp running down the walls on calm days. 

 

Neither was a choice and neither was  healthy. 

 

My dMEV airtight office and Tupperware tight house with MVHR spend much of the year with windows and doors open, kids creating havoc etc. When we do close them we still have plenty of fresh air and the icy North Atlantic gales stay outside where they belong. 

 

TLDR:

 

1.Airtightness is vital for comfort. 

 

2.Mechanical ventilation is vital for fresh air. Just decide what type suits you best.