Passivhaus Cat Flap

I’m much more of a cat person than a dog person and some provision needs to be made for cats in the new development. Passivhaus and cat flaps are generally incompatible – more due to the air tightness requirements than the thermal insulation – so initially I was thinking the cats would be accommodated in the outbuildings rather than in the main house. However, since there will be no outbuildings for a while I need to think again.

Fortunately there is a solution in the form of the Pet Walk pet door. It’s very expensive but it has clearly been designed with Passivhaus applications in mind. (It’s from Austria, home of a surprisingly large number of Passivhaus components.) In particular:

  • It passes the standard air tightness tests and performs as well as any other door or window
  • It’s very well insulated as standard with extra insulation (for the frame) available as an option
    • The advice from my Certified Passivhaus Designer is that it’s not necessary to model it separately since it performs as well as whatever wall or door it is installed in
  • It opens automatically (via a motor drive) in response to motion detectors and / or RFID chips
  • It locks securely and can be integrated into an intruder alarm system
Pet Walk pet door,

Pet Walk pet door,

Plan A was to install it in one of the walls, but with the walls being so thick (250mm cavity plus 2 x 100mm concrete blocks) that would require quite a long and wide “tunnel”, so Plan B is to install it in the side door. It would have been ideal if it would have fitted in the fixed side-light by the door but that is too narrow so it needs to go into the door itself. In some ways that will complicate matters, especially with respect to the 24V DC power supply, but a simple “door loop” can take care of that, as well as the integration into the alarm system.

One good feature is the wide range of clip-on covers that can make the inside and outside blend in with a variety of colours and surface finishes. They’re available in the same colours as the Internorm doors.

Update 2016-03-20: I have now purchased this cat flap in advance of it being fitted by the door installers. I’m not going to use the supplied plug-in power supply but instead hard-wire it using a separate 24V DC power supply and door loop. The supplied plug-in unit is rated 24V 1.0A so I am going to use a Mean Well DR-30-24 which mounts on a DIN rail and is rated 24V 1.5A.

The instructions say to cut off the supplied DC line socket when using a hard-wired power supply but I prefer to connect using a DC line plug (especially since I have several available). The correct size is: 5.5mm diameter with a 2.5mm pin and roughly 11mm long. The centre pin is positive.

CC BY-SA 4.0 Passivhaus Cat Flap by Marsh Flatts Farm Self Build Diary is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

10 thoughts on “Passivhaus Cat Flap

  1. Now that you’ve used it for a while, would you recommend it? Does it ever fail in any way (either by not opening, or by staying open)?

  2. Since I have yet to move into the house, the cat flap isn’t in use yet so I’m afraid I don’t have any feedback on how well it works just yet.
    The instructions mention it might not pick up an embedded RFID chip unless the cat is very close so the manufacturer recommends using a collar-mounted tag instead.
    Unlike most urban or suburban installations, my rural site has no other cats in the vicinity so I don’t need the cat flap to only open for specific pets and hence I can always use it in a simple presence-detection mode – at least until the cats get used to it.


    • Hello, now a few months on, have you moved in with the cat, and how is it working? I have a passivhaus 2 years old and am possibly going to put in a cat flap retrospectively. I’d be grateful for your views.

      • I’ve been living in the house for a couple of months now, with two cats. The cat flap is working fine so far. One of the cats took to it straight away but the other one took a couple of weeks to get used to it (but he’s about 18 years old, deaf and quite nervous).

        Obviously it’s an expensive item, but my Passivhaus consultant is happy it performs as well as the door it’s mounted in – both in terms of insulation and air tightness. There’s an option of an extra insulation panel which I didn’t bother with. It’s quite a big unit and so needs a fairly large hole in either a door or a wall. I had the door company cut the opening for me.

        I still have the cat flap set to open with just the motion sensors rather than checking for the cats’ microchips. There are no other cats in the area so I don’t have problems with other cats coming it, but it does mean the cat flap opens whenever I open the door (there’s an option to install a door contact to prevent that) or when working near the door, which is a bit annoying, but I could fix that by setting it to check for their chips.

        In summary, I’m happy with it so far. Over the winter the cats have been staying inside most of the time, but I know they’ll be outside more in the summer, and it’s good that they can come and go as they please.

  3. I am part of a new build scheme and would like to know how much it would cost to install a cat flap installed into an Passive built house/apartment. Thank you Cathy Roberts DT6 5BG UK

    • Cathy you’d need to contact the company directly Search for petwalk uk

      You can then email them

  4. My partner has just built a Passivhaus, now accredited – and then I arrived on the scene with a beloved cat. We are in a quandary and I have just found your Blog. Would you recommend your cat door?
    It’s the only thing that looks hopeful so far!!!

    • Hi Maggie,
      In a word – yes. It’s very expensive but it is well insulated and it is airtight. Mine is working perfectly after several years.
      I’m not aware of anything similar which performs to the required standard.
      If you’ve got somewhere suitable to install it without compromising the air tightness of the house (mine’s in the panel of an Internorm door) then it could be a good way to go.

  5. Hello
    This string is so useful. Just to clarify – we have Internorm triple glazed doors is this the type you installed your catflap in?

    • Hi Graham,

      The cat flap is in an Internorm door, but it’s got a solid panel (wood-effect inside; aluminium outside) and it was always specified to be cut-out for the cat flap. Retrofit into an existing door is likely to be more problematic, depending on the materials the door panel is made from.


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