Convection cleverness? Venting into the skylight?

[puntloos]

So I have a central hallway designed that goes all the way up to a large skylight.

 

Does it make sense to have rooms surrounding this hallway 'breathe into' this hallway by perhaps creating slots in the walls? I imagine having the house's hot air trickle into the skylight and when needed opening that skylight would be a very efficient way to shed heat. Especially the plant room I imagine.

 

- Am I overthinking things with properly designed high efficient house?

- Is this idea great in summer and terrible in winter (should I perhaps make the slits openable/closable?) 

- In general are passivhaus style rooms insulated from each other?

 

 

 

 

 

Edited November 15, 2021 by puntloos

[Nickfromwales]

3 hours ago, puntloos said:

Does it make sense to have rooms surrounding this hallway 'breathe into' this hallway by perhaps creating slots in the walls?

Given that they ( typically ) would be anyway, via the undercuts at the foot of each door, the question would be about the merits of making that happen higher up the wall. I cannot see any merit IMO, due to the low flow rates vs the reasonable concentration of 'rising heat' at that location.

Trade-off would be sound / noise / cross-talk from the rooms may be worse with the wall vents, and I personally would not want to spoil the look of the walls with the grilles. One member here ( IIRC ) created throughput for airflow at the heads of the doors by making a gap that was hidden by the header of the architrave. That seemed a better option, in general, vs the 10mm exaggerated gap at the foot of each door, but again I'd fear sound bouncing off the ceiling being taken in more by the higher level openings.

[MikeSharp01]

A passive stack is probably going to be a good thing as it will allow cooling of the whole house. What does the cross section look like? If the loft area is not subject to the MVHR system then the door undercuts will do little to help cooling as the hot air will all gather at the top of the space. You can get automatic louvres which could work with the window in hot periods to let the air out above the doors and the opening rooflight will help the whole house cool down even more if you are able to open windows low down in the house when needed. 

[Gone West]

5 hours ago, puntloos said:

In general are passivhaus style rooms insulated from each other?

No, the PH concept is that all rooms are the same temperature. In the PHPP there is one temperature input data which by default is 20C but which is a variable.

[puntloos]

8 hours ago, Nickfromwales said:

One member here ( IIRC ) created throughput for airflow at the heads of the doors by making a gap that was hidden by the header of the architrave. That seemed a better option, in general, vs the 10mm exaggerated gap at the foot of each door, but again I'd fear sound bouncing off the ceiling being taken in more by the higher level openings.

 

Do you have any suggestion how I can find this? Or any sketch to give me some idea? Searched for 'architrave header vent' etc on google but no obvious thing came up.

 

 

7 hours ago, MikeSharp01 said:

A passive stack is probably going to be a good thing as it will allow cooling of the whole house. What does the cross section look like?

 

My 3D program is pretty poor at roof/wall layouts  (and I'm also using it in terrible ways) so ignore any weird glitches. Obviously the skylight sits above the central hall. And yes, almost every house room is adjacent to this hall (only kitchen and master bedroom are not)

 

Quote

If the loft area is not subject to the MVHR system

I would imagine it is though, we haven't chosen that design aspect 

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then the door undercuts will do little to help cooling as the hot air will all gather at the top of the space. You

can get automatic louvres

Yes, this was somewhat my idea. I wonder if they block noise sufficiently well. I think @Nickfromwales hesitated at the view of louvres but I think it could work without being too horrid.

 

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which could work with the window in hot periods to let the air out above the doors and the opening rooflight will help the whole house cool down even more if you are able to open windows low down in the house when needed. 

 

Yes, I was just wondering about that realistic balance between a passivhaus having to be 100% airtight all the time to function and just doing the 'human' thing. 

I'm sure venting air up is not a bad idea.

Edited November 15, 2021 by puntloos

[Gone West]

13 hours ago, puntloos said:

Does it make sense to have rooms surrounding this hallway 'breathe into' this hallway by perhaps creating slots in the walls? I imagine having the house's hot air trickle into the skylight and when needed opening that skylight would be a very efficient way to shed heat.

Our stairwell came off the central hall room and the landing served three bedrooms and a bathroom. The bathroom had a roof window and in the summer, when it was hot, we opened the entrance door and the roof window, in the evening, to create a passive stack effect. It was amazing how much air movement there was and how effective it was at dumping the hot air. We tended to live with all the internal doors open all the time so air moved around the house.

[Gone West]

1 hour ago, puntloos said:

Yes, I was just wondering about that realistic balance between a passivhaus having to be 100% airtight all the time to function and just doing the 'human' thing. 

The airtightness is only important when it's colder outside than inside. In the summer the windows can be opened any time you want.

[Adsibob]

2 hours ago, puntloos said:

Do you have any suggestion how I can find this? Or any sketch to give me some idea? Searched for 'architrave header vent' etc on google but no obvious thing came up.

I think it was @jack who did something like this: http://porters-zch.co.uk/door-header/

[jack]

23 minutes ago, Adsibob said:

I think it was @jack who did something like this: http://porters-zch.co.uk/door-header/

 

Yes, we did this. To be honest, we rarely keep doors closed long enough for it to make much difference.

 

We were a bit worried about noise transfer, so we lined the inside of the aperture with some corrugated sound-absorbing foam (peaks and troughs aligned in direction of air travel). There's very little noise transfer, but I can't honestly say what impact the sound absorbing foam makes.

[puntloos]

1 minute ago, jack said:

 

Yes, we did this. To be honest, we rarely keep doors closed long enough for it to make much difference.

 

We were a bit worried about noise transfer, so we lined the inside of the aperture with some corrugated sound-absorbing foam (peaks and troughs aligned in direction of air travel). There's very little noise transfer, but I can't honestly say what impact the sound absorbing foam makes.

 

Interesting stuff thanks @Adsibob and Jack - very interestig stuff. Jack - is your house anywhere near passiv? As people say apparently having air circulate is absolutely fine in passiv too so I doubt it really matters. my only exception is that I have a networking closet that is kinda hot and I can't just have that heat go out into the rest of the house.

 

[jack]

Yes, passivhaus levels of insulation and airtightness.

 

The main reason you need some sort of route for air between rooms is MVHR (in fact, it's a building regs requirement).

 

I don't use stack ventilation, mainly because we have issues with insects getting in.