Advice on MVHR (retrofitting, reducing Carbon Dioxide and Radon levels)

[Kuro507]

We live in a modern timber frame house, built circa 2001, manufactured in a factory and assembled on site. 

Triple glazed windows, concrete block shell and render finish.

 

I've recently become concerned that CO2 levels in my home office are high, causing drowsiness and lack of concentration. This led me to purchasing a couple of Carbon Dioxide monitors, both of which show regular figures over 2,000 ppm in my office. Moving the sensors around shows similar figures in our master bedroom overnight.

One of the sensors (Airthings Wave Plus) also measured Radon and occasionally it goes into the warning level (>200Bq/m3).

 

The sensor will be moved to both the kids bedrooms and a week or two, to see their levels.

 

I am assuming our house is pretty airtight, certainly it is always warm.

 

We need to replace 3 extractor fans in bathrooms and a WC,  I am toying with the idea of installing a MVHR instead, recovering some of the heat that would otherwise be lost and also having the ability to bring in fresh air and extract the stale.

Upstairs would be easy to install, I could use existing 100mm vents to outside and then simply run pipework in the loft to 3 bedrooms, en-suite, main bathroom and 2-storey hallway/landing. Downstairs would be more complex to get pipes through to.

 

I guess an advantage would be better circulation of heat through the house?

 

Have any of you retrofitted MVHR to your home?

 

Have any of you installed MVHR to improve CO2 or reduce Radon in your home?

 

As always, I value your thoughts and ideas on the above, thanks for reading

 

Edited yesterday at 14:51 by Kuro507

[Oz07]

Single room units might be better?

[Gone West]

59 minutes ago, Kuro507 said:

I am assuming our house is pretty airtight, certainly it is always warm.

Would it be a good idea to have an airtightness test done. Then you can also see where the leaks are.

[Mike]

Your measurements are certainly far from ideal. You mention the existing air extraction methods, but I'm wondering how air is currently drawn into the building and, in particular, whether those triple glazed windows include trickle vents that are actively used. If not, that would be cheaper than installing MVHR and may bring down CO2 levels enough, though they do have drawbacks.

 

4 hours ago, Kuro507 said:

Have any of you retrofitted MVHR to your home?

There have been a couple of discussions about retrofitting MVHR here - it's mentioned in some posts with @Garald as a future project, but not sure if anyone has done it. It's possible but disruptive, so easier to do during a renovation, as I have. It would certainly be an effective way of bringing the CO2 levels down.

 

4 hours ago, Kuro507 said:

I guess an advantage would be better circulation of heat through the house?

Air has a low heat capacity so isn't great for moving heat around, so it's not going to help that much at normal MVHR speeds. It can help to bring in cooler summer night air if the MVHR unit has a decent bypass fitted but, if you live somewhere when you can open the windows, that's a cheaper option.

 

4 hours ago, Kuro507 said:

One of the sensors (Airthings Wave Plus) also measured Radon and occasionally it goes into the warning level (>200Bq/m3)

There are remedial measures that can be taken to tackle Radon and I'd recommend looking into those:

https://www.ukhsa-protectionservices.org.uk/radon/information/reducelevels