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Increasing air flow, reducing heat loss in 1980s property


KBuckland
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I'm looking for advice for when it comes to future proofing my home, since I'm about to have some building work done (an interior wall down, kitchen & living room gutted and redecorated). I'm trying to make my home a bit more efficient if possible, but also recognise that I need decent air flow. I have a 1980s detached brick house with cavity wall insulation, good loft insulation, double glazing, concrete floor, gas central heating. Most downstairs windows have trickle vents, upstairs does not.

 

With trickle vents closed and windows closed, the house tends to hold onto heat quite well. During the recent storms I found a few gaps around windows where wind could come through, so I will seal those soon. The trickle vents work well when open, but also seem to seal well when closed.

 

I don't have any issues with condensation downstairs, but the air in the house can become quite stale in winter and smells from cooking, etc tend to linger for a long time. Upstairs I get a little bit of mould at the very top of the outside walls - presumably where the top of the wall meets the roof and cool air is circulating into the loft from outside and cooling this part of the wall and ceiling. Usually I can wipe these areas once or twice a year which keeps any mould away, but this again suggests to me that airflow is probably an issue. This is less of an issue in my upstairs bathrooms as they have extraction fans which run for a decent amount of time after use, but here I feel like I am venting lots of hot air alongside any moisture, which feels wasteful.

 

I also recently got my hands on a co2/humidity/temperature monitor, which confirms to me that humidity in the house is fine, but co2 levels can get a little high (up to 2000ppm at their peak for a few hours in the evening).

 

So, in short I think I need to increase air flow throughout the house, but try to reduce heat loss if possible.

 

I am a little confused by the available options. So far I've been made aware of MVHR, d-MVHR and PIV. Whole house MVHR is probably going to be quite expensive and destructive. I don't see where I could get vents to my ground floor, for example. Presumably only installing on the first floor (from the loft - which would be easy) is a bit pointless. d-MVHR seems like it would be much easier to install bit by bit, although I am worried that some of the units might be noisy. Is there d-MVHR that would work well for a bathroom or kitchen? PIV is clearly the easiest to install, but would it help much?

 

I would appreciate any help or advice offered. Thanks!

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Sorry -  a few more thoughts.

 

With regards to whole-house MVHR - I have just read about semi-rigid 75mm radial ducting, so perhaps I could run those either through existing boxed-off areas (where existing pipes are run) or through my built-in wardrobes - which would cover most downstairs rooms. If I am considering MVHR am I best off getting someone in to do it (I have read there are quite a few bad installations done in the UK) or learning to do it myself? How hard is it to get it right? Similarly, should I get an air-tightness test done first to see if MVHR makes any sense in the first place?

 

With regards to d-MVHR and MVHR, could I combine them and do MVHR on the first floor and d-MVHR in some rooms on the ground floor?

 

Or perhaps PIV would do a 'good enough' job at ventilation and if the house is simply not efficient enough any form of MVHR might be pointless.

 

I think more than anything else I need the benefit of other people's experience to guide me here. Thanks!

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