Green Building Forum - Ventilation for New Build Tue, 19 Dec 2023 08:25:15 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276320#Comment_276320 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276320#Comment_276320 Tue, 22 Oct 2019 19:57:09 +0100 bardo
The cooker and bathroom share the same party wall.

Our walls are wide : 550mm (straw bales 450mm wide with another 100mm of lime / cladding/battens on the outside wall).

Can anyone recommend a simple effective way of doing this Do we really need MVHR or just a simple extractor fan? Any brand/models?

Thanks]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276328#Comment_276328 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276328#Comment_276328 Tue, 22 Oct 2019 22:55:15 +0100 tony Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276331#Comment_276331 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276331#Comment_276331 Wed, 23 Oct 2019 09:31:06 +0100 GreenPaddy
Try googling..."single room heat recovery"

That will bring up various unit that are a bit like an extract fan, but have heat recovery built in. It should also bring up small MVHR units, which would involve some ducting (makes like Boulder and Quiet-vent 150) - a few hundred quid, rather than £1500 for the large units.

See what you think, and maybe come back for more thoughts?]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276335#Comment_276335 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276335#Comment_276335 Wed, 23 Oct 2019 12:08:50 +0100 jfb
Presumably in a straw bale house the render on the inside is the airtight layer. So long as you pay close attention to details of junctions between different materials, windows/walls, walls/roof, it is very possible to get a good air test result and get well below 3.]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276338#Comment_276338 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276338#Comment_276338 Wed, 23 Oct 2019 13:25:34 +0100 CWatters
If your house isn't air tight you end up with some unknown and uncontrollable amount of ventilation and a matching heat loss.

If you build an air tight house you can/must control the ventilation by designing it in. You could specify adjustable trickle vents but with these you get limited control because ventilation depends on the wind. You also loose heat because air goes in some vents and out of others.

MVHR is much better. Not only because air goes in and out via a heat exchanger recovering the heat but you can control which rooms get incoming fresh air and which rooms have extract vents (at the design stage).

We opted for MVHR and was surprised to find we didn't need a separate extractor fan (or boost option on the MVHR) in the bathroom despite four of us using the shower. Your mileage may vary.

We did fit an extractor fan over the hob but it's not used a lot.]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276341#Comment_276341 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276341#Comment_276341 Wed, 23 Oct 2019 14:24:37 +0100 bardo


Posted By: CWattersIn my opinion it's all about control...

If your house isn't air tight you end up with some unknown and uncontrollable amount of ventilation and a matching heat loss.

If you build an air tight house you can/must control the ventilation by designing it in. You could specify adjustable trickle vents but with these you get limited control because ventilation depends on the wind. You also loose heat because air goes in some vents and out of others.

MVHR is much better. Not only because air goes in and out via a heat exchanger recovering the heat but you can control which rooms get incoming fresh air and which rooms have extract vents (at the design stage).

We opted for MVHR and was surprised to find we didn't need a separate extractor fan (or boost option on the MVHR) in the bathroom despite four of us using the shower. Your mileage may vary.

We did fit an extractor fan over the hob but it's not used a lot.
]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276344#Comment_276344 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276344#Comment_276344 Wed, 23 Oct 2019 18:00:45 +0100 Peter_in_Hungary Posted By: bardoWe have gone for adjustable trickle vents in the windows despite the mentioned reasons. The calculated heat loss is around 3kW.
3kW per what? hour? day? month? or a continuous 3kW loss?]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276346#Comment_276346 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276346#Comment_276346 Wed, 23 Oct 2019 20:11:55 +0100 djh Posted By: Peter_in_Hungary
Posted By: bardoWe have gone for adjustable trickle vents in the windows despite the mentioned reasons. The calculated heat loss is around 3kW.

3kW per what? hour? day? month? or a continuous 3kW loss?
Normally such figures, and the corresponding heat load figure, refer to the maximum rate of heat loss/supply needed to keep the house at a constant temperature at all times. The heat load will be greater if heating the house from cold. Normally, the maximum heat loss will be experienced when the outside temperature is at the minimum design temperature and the wind is blowing at maximum design speed.]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276348#Comment_276348 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276348#Comment_276348 Wed, 23 Oct 2019 22:39:52 +0100 Mike1 Posted By: bardoThanks all. We have gone for adjustable trickle vents in the windows despite the mentioned reasons.
Apart from the mentioned reasons, personally I'd also avoid trickle vents (at least in an urban situation) because of the noise they let through.]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276354#Comment_276354 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=276354#Comment_276354 Thu, 24 Oct 2019 12:30:29 +0100 owlman Does anyone know of a ceiling mounted single room MVHR unit? or, a wall mount for directly under the ceiling where the inlet/outlet has a top entry and can be angled to outside in the loft void?]]> Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277681#Comment_277681 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277681#Comment_277681 Fri, 03 Jan 2020 13:14:16 +0000 riboid007 Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277684#Comment_277684 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277684#Comment_277684 Fri, 03 Jan 2020 15:56:32 +0000 philedge Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277694#Comment_277694 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277694#Comment_277694 Fri, 03 Jan 2020 20:10:59 +0000 tony Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277701#Comment_277701 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277701#Comment_277701 Sat, 04 Jan 2020 11:35:13 +0000 djh Ventilation for New Build http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277708#Comment_277708 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16298&Focus=277708#Comment_277708 Sun, 05 Jan 2020 12:26:33 +0000 Simon Still
Uses centrifugal force rather than just a metal mesh to remove the oil from the extracted air. Extra large, refillable carbon filter if using in recirculation mode or an insulated outlet that only opens when in use if extracting.

Ours is recirculating with the kitchen MVHR extract relatively nearby. Very effective and easy to clean.

After 4 years I've just changed the carbon pellets in the filter - since they're a widely available 4mm pellet used in other filtration systems that cost just £25 (they recommend changing about every 3 years). Most other recirc hoods recommend changing at least annually and a quick look at the Siemens site shows some of their replacement sets are over £100.

When I changed the carbon there was negligible sign of grease that had got past the filters (whereas when I've cleaned the mesh filters of conventional cooker hoods theres a fair amount of grease coating the insides).

Yes, they're super expensive but also very solidly made of heavy grade stainless steel and with very quiet motors.]]>