Building control drawings

[JohnMo]

14 minutes ago, nwnw said:

Has anyone ever worked out the cost/heat impact of a dMEV running constantly?

Atamate_SDAR+Paper+2019+(1).pdf

[nwnw]

15 hours ago, JohnMo said:

Atamate_SDAR+Paper+2019+(1).pdf 2.47 MB · 46 downloads

Thanks for that.  Had a quick read, but it seemed to me that it wasn't possible to draw any definite conclusions.  Too many variables.

I was thinking more down the lines of a simple calculation...how much volume of 20degC air is removed each year with dMEV vs intermittent vs MHRV and how many kWh does it take to heat that air?

[Mr Punter]

16 hours ago, nwnw said:

Has anyone ever worked out the cost/heat impact of a dMEV running constantly?  I'm not worried about the 0.5W to run.  I'm thinking how many kWh of warm air is being blown out in the winter?  I'm curious to see if single room MHRV would be cheaper in the long run?

 

Maybe base it on extract rate of 10l/s and temperature difference of 10 degrees, year round.

[JohnMo]

some more reading

 

FLY528GB_v2_display.pdf AIVC-2.pdf Construct-Ireland-February-2011-2.pdf

[timhowes]

Very timely thread as we are probably switching our plans away from MVHR and instead towards dMEV.

 

We will most likely want humidity-activated through-wall inlets rather than trickle vents. Does anyone have testimonials regarding the external noise transmission with these, please? Hoping not to be woken up with the birds (acknowledging that there are far worse things by which to be woken!)

[JohnMo]

2 minutes ago, timhowes said:

Very timely thread as we are probably switching our plans away from MVHR and instead towards dMEV.

 

We will most likely want humidity-activated through-wall inlets rather than trickle vents. Does anyone have testimonials regarding the external noise transmission with these, please? Hoping not to be woken up with the birds (acknowledging that there are far worse things by which to be woken!)

You can buy then with acoustic sound deadening as well.

[timhowes]

Thanks. I did search for such but can't find any - can you suggest any examples please?

[JohnMo]

https://www.bpdstore.co.uk/glidevale-fresh-99hdb-humidity-sensitive-acoustic-wall-ventilator/p/232

 

The first one I came across 

[JohnMo]

Some better looking stuff on here

https://www.aereco.co.uk/products/air-inlets-uk/eht2/

[Mr Punter]

4 minutes ago, JohnMo said:

https://www.bpdstore.co.uk/glidevale-fresh-99hdb-humidity-sensitive-acoustic-wall-ventilator/p/232

 

The first one I came across 

 

I think that is the only one available.

[timhowes]

Thanks both, very helpful

[nwnw]

14 hours ago, Mr Punter said:

 

Maybe base it on extract rate of 10l/s and temperature difference of 10 degrees, year round.

Based on this, we would blow 864,000ltr of warm air into the atmosphere every day.  At approx 0.003kWh/1000ltr, that suggests about 2.6kWh/day (946kWh/yr).

Depending on your heating system and tariff, that could be anything from £16 (ASHP & cheap tariff) to £70 (gas boiler) per year.

It would certainly add up and worth taking into account.

[JohnMo]

7 hours ago, nwnw said:

that suggests about 2.6kWh/day (946kWh/yr)

You experience the ventilation heat loss on heating days only. Plus you experience it based on dT between and outside, not a set figure every day. Plus if you do demand based the ventilation heat loss is proportional to actual demand, not a steady state.

 

 

[Crofter]

Interesting thread. I'm a big fan of Sketchup, I've never got to grips with any sort of traditional CAD though. I'm currently running an obsolete (2017) version on a ten year old Mac with a screen the size of a small cinema, it's amazing.

I hadn't really thought of using it for BW drawings though- @nwnware you going to screen grab different views and submit those? Or do you think BCO will actually want to look around the 3D model?

I've never added any labels or info to the models, is that possible/easy?

[nwnw]

On 18/11/2025 at 08:37, JohnMo said:

You experience the ventilation heat loss on heating days only. Plus you experience it based on dT between and outside, not a set figure every day. Plus if you do demand based the ventilation heat loss is proportional to actual demand, not a steady state.

Yes, I was taking the 10deg dT as a rough average for the year.  Probably not far off for me (North East Scotland), but maybe a bit high for others.

[nwnw]

On 18/11/2025 at 09:15, Crofter said:

Interesting thread. I'm a big fan of Sketchup, I've never got to grips with any sort of traditional CAD though. I'm currently running an obsolete (2017) version on a ten year old Mac with a screen the size of a small cinema, it's amazing.

I hadn't really thought of using it for BW drawings though- @nwnware you going to screen grab different views and submit those? Or do you think BCO will actually want to look around the 3D model?

I've never added any labels or info to the models, is that possible/easy?

@Crofter, did you look at some of the drawings I attached earlier?  I use Sketchup and Sketchup Layout.  You basically create a scene in Sketchup then import the scene into a layout view.  The scenes can have any sort of x-section and view style.  Any changes you do in Sketchup get reflected in the Layout view.  You can add dimensions, notes, annotations - you just need to be careful not to change the zoom scale of the scene once created.

Also, as mentioned earlier, you need to get used to using Groups, Components and Tags, so that you don't keep messing up your model.  Using it properly was a game-changer for me.

I've worked with various CAD packages over the last 30 years or so.  Sketchup is not quite as intuitive or as packed with features, but it's free and it's great for visualisation.  Being able to stand in a spot and see the view of the room in the correct perspective is invaluable.

[JohnMo]

1 hour ago, nwnw said:

Yes, I was taking the 10deg dT as a rough average for the year.  Probably not far off for me (North East Scotland), but maybe a bit high for others.

As the difference between outside and inside gets wider (colder outside) the heating system starts to dry the air on a well ventilated house. So if running a humidity activated system the ventilation system will start to close in.

 

I have humidity sensor in our summer house, which is heated all the time, it's currently 22 degs in there, with two people in there and humidity is 31%. That's with dMEV fan running at minimum speed (need to double check that - note to self). 

[nwnw]

On 19/11/2025 at 10:53, JohnMo said:

As the difference between outside and inside gets wider (colder outside) the heating system starts to dry the air on a well ventilated house. So if running a humidity activated system the ventilation system will start to close in.

 

I have humidity sensor in our summer house, which is heated all the time, it's currently 22 degs in there, with two people in there and humidity is 31%. That's with dMEV fan running at minimum speed (need to double check that - note to self). 

So 10ltr/s yearly average is too high. What's your best guess?

[JohnMo]

4 minutes ago, nwnw said:

So 10ltr/s yearly average is too high. What's your best guess?

No idea, no idea if the house size etc and how many people live there.

 

MVHR you really need an airtightness of around 3 or your wasting money. Worse than that I would only do dMEV or MEV based humidity control.

 

After moving away from intermittent fans, that are noisy and perform rubbish, wouldn't go back to them.  A well thought out MEV or dMEV will yield lowest lowest ventilation heat loss and best control of humidity, with almost no running costs. So humidity controlled inlets in dry rooms, humidity driven fan from a MEV or dMEV system, all doors under to allow ventilation cross flow with doors closed.