Super-high performance windows versus trickle vents - what do they do in Scandinavia ?

[clive.r.long]

As I understand, typical UK domestic windows have trickle vents to try to a llow warm, damp air to escape a room (and cold, dry air to enter) to avoid or reduce condensation on the windows.

Now what I have never understood is, and does anyone know if there is hard data on this,

1) Say you have fabulous high-tech glass, triple-glazed, argon-filled units with thermal barrier window frames, all professionally installed, what per centage (typical UK weather conditions) of the "heat saved" is then lost th rough the trickle vent?

2) Can the windows be sealed as tight as a drum to limit air exchange throu gh them to a minimum - but the ventilation requirements be met using a thro ugh-the-wall ventilation unit? the advantage of these being as I understand is they heat the incoming air via a heat exchange to limit heat loss and t he effects of inbound cold air triggering condensation?

3) What do the Scandinavians or Icelanders have installed in their glazing units? Do they have trickle vents in the frames? Is there any research on t heir experience of window pane or frame condensation?

I will declare my prejudice that I suspect trickle vents are a lazy, counte r-effective solution to condensation and there are "better" solutions - but I am very happy to be shown to be wrong in that prejudice.

Ta,

Clive

[Bill Taylor]

Houses that are designed for high performance won't have trickle vents but have Mechanical Ventilation with Heat Recovery (MHVR).

A whole house MVHR system will extract moist air from the kitchen, bathrooms and toilets and introduce fresh air to living rooms. The heat exchanger warms up the fresh air by extracting heat from the stale air.

The result is clean dry air in the house with little heat loss.

Trickle vents are an attempt to reduce condensation when sealed windows are installed in a house that has inadequate ventilation.

[tim...]

modern Scandinavian building requirements are that a house should be 100% "sealed".

Ventilation is provided by a forced air system from a pump in an out building

tim

[Andy Burns]

When open, or closed?

No, the closers on trickle vents are not tight as a drum, IME.

[Huge]

The window fitting company we're presently talking say that most people silicone the trickle vents shut ...

[dennis]

You probably can't measure the air flow on mine when the vents are shut. Even with a gale blowing you can't feel anything. There is far more through a keyhole.

[Andy Burns]

I agree there is more draft through even a eurolock keyhole, but I do occasionally see curtains twitch in high winds from the trickle vents.

[Tim Streater]

We told 'em we didn't want them. Were able to get away with that as they were replacements for some dg units that didn't have TVs.

[The Natural Philosopher]

about 70-90%

If that is where you are at, you need to install oassive heat exchanger ventilators - concentric tubes with warm air going up the middle and caold air coming down the outside.

yes.

No. Trvckle venst are a menas for aftermarket units to comply with building regs. New buods do use them from laziness, but ultinmatley they are bot as good as passive units

No, IMHO you are spot on the button.

Most people paint em shut

Unless you have massive internal seals things like kitchen and bathroom extractors suplly enough circulation to keep codensation down

[John Rumm]

On many windows the trickle vent is implemented simply by a second catch position on the window latch - so they can be locked shut but partially "open".

Once with actual trickle vents normally have some form of closure mechanism to allow the vent to be shut off.

I think they are there to provide the option of some background ventilation. More valued in modern houses that are in many cases otherwise air tight.

It may not be particularly effective from an energy saving perspective (when in use), but can be beneficial from an air quality PoV.

[John Rumm]

When I bought the windows for my loft conversion (c. 2004, so rules may now be different), the manufacturer asked if I actually wanted separate vents or if I would be happy with the double latching capability of the lock alone. I opened for both since I did not know what the LABC would require. It turned out that they would have been happy with the double latch only.

[The Natural Philosopher]

in 2000 I ran foul of that. Because the part latch was deemed to be unsuitable for ground floor use for security reasons. Despite the house being 100% occupiie by dogs or humans at almost all times. or the windows being shut tight when not so occupied.

But vents to fires and provided enough bventialtion but that wasnt allowed either becuse they were sub floor, but overall there were enough fans in the house to act as inlets and exhausts....

[Andy Burns]

I get far more ventilation (I'd call it wind) through by leaving just the top opener on the first latch position, than by opening the trickle vent.

It's not as though there's a straight path through the vent, the air has to go up through the insect screen, across through the body of the frame and then down into the room if the flap is open ...

[dennis]

and you can control the size with a bit of tape.

[Harry Bloomfield]

The Natural Philosopher was thinking very hard :

The double latch is the type we have all round and they were installed in around 2011.

[tim...]

I don't see how this is a bad thing

They do the job that they are intended to do

not the job that leaving the window locked in first open position does

The ideas here that there are synonymous is silly.

I leave my trickle vents open in the winter whilst the heating is on - without thinking that maybe I am paying to heat the outside world

I can't do that with the windows locked in first open position

tim

[Tim Streater]

And what happens with a howling gale aimed straight at those windows?

[dennis]

You shut one or more of them. They don't leak just because its windy. If they do then you need to fit better ones.

[tim...]

as I don't live on the top of a windswept moor, that never happens

tim