Draught lobbies – warm or cold

[Alan Clarke]

Any experience on whether draught lobbies are better inside the insulated / airtight envelope or outside it? 

[David Olivier]

They're better projecting out from the building (porches in old houses often do). The heated building may remain a rectangle and is relatively easily-detailed for low heat loss. But this seems uncommon in new buildings.

I've heard reports that no matter what one does in non-domestic buildings, a large number of clients later heat the lobby. If this is going to happen it would be better to locate it inside the building footprint (keeping this rectangular if possible) and treat its outer wall as the boundary of the thermal envelope.

David.

[Nick Grant]

David makes good points.

Our experience of a small utility room acting as a draft lobby/buffer zone outside the heated envelope is that it is cold (fine). However in freezing weather when the inner door is opened and warm air at say 45% RH floods into the lobby, condensation forms on the cold windows.

I guess if it was just a porch it would be fine so conclusion is either a well ventilated porch that might freeze or a heated utility room in the thermal envelope?

Nick

[David Olivier]

Yes it should be draughty enough for water not to condense. Plumbing wouldn't be safe.

Even then surface condensation will occur whenever a spell of mild humid weather (SW wind) follows a spell of cold dry weather (like the weather right now). If it was built without a door, the end near the building would need to be protected well enough to stay free of driven rain or snow. But then it's not an airlock!

D.

[Anonymous]

My wife spends so much time chatting at the back door with all doors OPEN it doesn,t really matter if the lobby is inside or out!

[Anonymous]

My wife spends so much time chatting at the back door with all doors OPEN it doesn,t really matter if the lobby is inside or out!

Know the feeling, first thing I do when I get in is shut the internal porch door and turn off all the lights that she's left on all over the house

[Nick Grant]

Boys, I thing we need another board!

We are turning into our fathers….

🙂

[Anonymous]

🙂

[SimmondsMills]

Draught lobbies – now then. All draught lobbies I have had in various houses were too small to use as such: because I usually had large parcels, bags, pieces of wood, toolboxes etc, and latterly double push chairs and larger parcels and even more bags. Too snmall a lobby (external to heated fabric) meant at least one door was usually open, either as we passed through the space (allowing wind and snow in etc) or because by the time we had negotiated all the stuff of modern living through the space we could not be bothered to shut the door.

IMO lobbies need to be more like 'working' hallways to allow for this..larger, with door closers (?) on inner door, and so being larger will be treated as heated spaces, either initially or with new owners. I also assume that this space may be commonly used for utility, growing space, 'conservatory' – uses that could work against the space being in the heated envelope.

Question is, is there a role for an external covered porch (as well as the working hallway) that simply shields against wind and a degree of rain, but has no external door?

Maybe there is an alternative design approach that caters for these sort of conflicting requirements, whilst not being within the heated fabric?

Is there research looking at whether domestic wind lobbies actually do work / save energy?

[Nick Grant]

I agree Andy. If it's really cold you will not leave the door open long, otherwise you might get 0.25 of an airchange when someone comes in, neither here nor there (I made up the figure of course).

Couple of good functions of an open portch:

1. protection from rain as you fumble with keys/shopping.
2. protection of door from sun and wet – very good reason.

[Author]

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