Ventilation and energy saving for a flat in a badly converted mill

[PeterB]

I stumbled on this site while researching MVHR and saw some great discussions and expertise. I have a 112 m2 top floor flat part of a mill converted in 1995. I am looking at sensible upgrades for the next 10-15 years. Presently I have Electrical heating (1995 storage heaters) 12000 kWh pa , aluminium double glazing from 2010 (3 x 6 panel windows 2.3mx1.6m), have heard mention that frames are not thermally efficient, thick solid stone walls (580mm window returns) insulation status unknown, 3.5m high ceilings lounge hallway and bedrooms, observed 200mm loft insulation.  Lounge and bedrooms are long and narrow and perhaps not well suited to present (lack of ventilation)

Perhaps the biggest immediate concern for next winter is high CO2 levels (measured by Awair sensor) in the flat unless windows are opened. It also gets very stuffy in summer and I suffer from hay fever. There is no vent fan (apart from cooker hood with activated carbon filter) in the kitchen. Its been blocked up probably because the flexible trunking collapsed(a neighbour experienced this). The only connections to the outside are two 95mm?(100 nominal?) holes through the stone work which are connected through boxed in trunking along the floor (wouldn't mind moving it up to reclaim floor space) to kitchen (originally) on one, and 2 bathrooms on the other. The bathroom fans suck but no perceptible flow at outside of building. Maybe disconnected by previous owner and routed into loft space (on the other side of a fire division - not good)

I am thinking that PIV system might be best rather than MVHR due to forum mentions on air leakage, although a lot of it might be beneficial in terms of heat input... The available 95mm openings are in bedrooms and I need to minimise cold piping, Can I use one opening for fresh air and one to take kitchen and 2 bathrooms out. Or is there a way to alternate (breathe in, breathe out, like ....lungs...)

For moisture control, I tend to finish the timed laundry for when I can use the dehumidifier on Economy 7 for a couple of hours in the morning (early riser). I see the dehumidifier as effectively free to run as I have electric heating anyway.

Seeking expert commentary, please, especially on whether I can get good ventilation with the two 95mm openings to the outside. Can I anyone recommend an approach and contacts for HVAC design?

[ProDave]

I would say with your high CO2 levels and feeling of being stuffy that the air tightness is pretty good, so I would be looking at mvhr in  the loft.  First thing to check is does the lease include the loft to allow you to do this?

[PeterB]

1 hour ago, ProDave said:

I would say with your high CO2 levels and feeling of being stuffy that the air tightness is pretty good, so I would be looking at mvhr in  the loft.  First thing to check is does the lease include the loft to allow you to do this?

I do wonder though if the stuffiness is coming from other flats! Only just got the Co2 meter and there's been no wind since so Im not sure if there's much coming in/going out through windows. The roof space is last resort as access is not easy at all. Also I thought I only have 95mm opening i need to keep pipe lengths as short as possible. Not sure how 95 mm compares with others, especially on inlet side. And need to keep cold pipe as short as possible?

 

Edited April 21, 2021 by PeterB