We are going to build an airtight porch to create an airlock so the MVHR doesn’t get overworked when letting the dogs in and out several times per day - we want a porch for other reasons also.

Here’s what I’m thinking:

Fit a door sensor to the internal door
Install an airtight mechanical vent in the porch that can be automatically opened based on humidity levels and when the door sensor is closed.

We’ll install an electric heater to dry damp coats etc, this will be manually controlled and we’ll leave the internal door open when in use to recycle the heat

I got excited when I read about Shelly devices on the ‘electric heating thread’ by @djh, but then saw that they can be fiddly. My hubby has used raspberry pi to do other automation tasks (not house related) that could be an option.

Wanted to get a view on any other methods people have used and if anyone has done something similar.

Also, I’ve looked for a mechanical vent but they all seem to be fans and don’t mention air tightness levels when closed. Would a fan type be recommended, perhaps it could have different settings (open, low fan, high fan) based on humidity level?

Any advice welcomed

It’s a 1960s bungalow that we are making as air tight as possible and then installing ventaxia MVHR. The clothes storage would only be to dry off, hence the heating and ventilation requirement.

Other reasons: mostly dog control, so I can contain them to clean muddy feet etc; we have a cat so thinking of double cat flaps (to reduce air leakage) with sensor to let us know she’s in - she’s always had cat flap into the house and taking that away completely feels mean

And mostly, I don’t like the idea of losing all the heat when we open the doors.

Posted By: GreenApprenticeThe clothes storage would only be to dry off, hence the heating and ventilation requirement.
Other reasons: mostly dog control, so I can contain them to clean muddy feet etc;

Ah OK. Sort of a mud room or boot room. Things dry very well in a house with MVHR - we don't often have clothes so wet we need to do anything other than hang them in the hall by the front door for a while. Or maybe in the conservatory. But then we only have cats - no dogs Occasionally we'll hang something over the bath or in a shower - usually if it's just been washed and can't be put outside for some reason.

we have a cat so thinking of double cat flaps (to reduce air leakage) with sensor to let us know she’s in - she’s always had cat flap into the house and taking that away completely feels mean

We have double cat flaps. One in the airtight wall from https://freedompetpass.ca/ that leads into the 'bin store'* and a chip-reading one in the outer wall of that (Sureflap I think).

* the bin store was supposedly just that - enclosed but not heated, not airtight. In fact it's used more as a larder. About 3 m x 1.25 m.

I don’t like the idea of losing all the heat when we open the doors.

You don't lose much heat - there's no air movement into or out of the house because it's airtight and the specific heat of air is really low in any case. At a guess - put an extra lightbulb near the door if you feel really guilty.