Are double height rooms in any way acceptable in low energy homes?

Too much heat rises increasing temperatures and heat losses and energy use.

According to the energy consultant we spoke to for our own build, as warmed air rises it loses its energy causing it to cool and fall again. May or may not be overly simplistic idea but I can see where his thought was coming from. This was in relation to underfloor heating being run at relatively low temperatures and I would imagine that heat from radiators might behave differently due to the higher temperatures and more concentrated nature of its delivery.

You could say that double height spaces won't do any favours to your exterior surface area to treated floor area ratio which may make it more difficult to achieve things like passive house standards for space heating requirements.

One concept I've been mulling over (presently for a commercial building) is to incorporate a mono pitch roof, falling to the north, 2 storey at south elevation, single on north, upper floor fairly open so that incoming light/solar gain can penetrate to the spaces on the northern side. Use row of PV panels for shading in summer over both levels of windows on southern elevation.

Posted By: jamesingramIf it's a vault ceiling in a single storey extension , then yes , brings more of the structure into the insulation envelope.

This is true & it helps to avoid the awful "inbetween space" which is the typical UK loft. However, a roof pitch of 45 degrees will increase the ceiling area by 41% and achieving the same total heat loss will require the insulation to be 41% thicker. So in total you'll need 100% more insulation.

If this insulation were creating additional habitable space, as in a loft conversion, then it can easily be justified. But a vaulted ceiling doesn't create any additional habitable space & most people wouldn't use 100% more insulation!

David

It's worth it for the space-and-light feeling.

Don' forget, if it's high in middle or at the high-monopitch edge, it can be really low - bare door height or even less - at the low edge. That way your volume and (much more important) your external surface to floor ratio may not end up that much different.

Also don't overlook stack height - the airtight volume's total ht from lowest to apex - actual air leakage is more or less proportional to that, for given blower-door test rating.

My single-story-plus-loft A-frame design has relatively low ceilings in the bedrooms, bathroom and kitchen with the loft space over them. Adding a bit to the room heights in those room would expand the building disproportionately. To compensate I plan cathedral ceilings in the living room and adjacent (near-open-plan) office/study. The kitchen will also be open plan to the living room but with the step down in ceiling height to mark the difference.

I think this is a reasonable compromise to make what's basically a pretty small house feel a bit bigger. A bit like the scheme in last night's Grand Designs which was one of the half dozen or so houses on that series that I actually liked.

I don't disagree with the any of the points above, a house has to have some architectural features, light & space are valuable in themselves & I wouldn't want to go to all the effort of building my own house just to have it look like a developers house. However, for people who spend a lot of time arguing about a few Watts here & there, we are very easily persuaded that adding significantly to the heat loss area is justified.

David

Posted By: slidersx200This was in relation to underfloor heating being run at relatively low temperatures and I would imagine that heat from radiators might behave differently due to the higher temperatures and more concentrated nature of its delivery.

This is an oft discussed area. UFH tends to heat the layer of air close to the floor. Humans generally like to have warm feet and cooler head so UFH works. The caveat is that UFH works best in well insulated houses as the temperature gradient (floor to ceiling) does not need to be too great to get the warm feeling.

Radiators are the most poorly named items ever. They are in fact convectors and heat a space by getting air to move by convection past the warm surface. This then naturally creates an airflow where warm air rises past the radiator and falls/ is pushed down as it cools - thus creating airflow.

So, If you have high ceilings and radiators it is generally a bad thing (one of the reason old churches are so cold). High ceilings and UFH work better.

Final thought is MHRV in this. Obviously the inlet/extract is at the ceiling. If you are creating airflow by radiators I suspect this is a less optimal solution than creating a warm air layer close to the floor with UFH. There is a possibility that the MHRV will then tend to circulate the air higher up in the room potentially reducing the amount of warm air extracted. It all depends on how the air stratifies within the building especially if there are no other drafts.

Posted By: jamesingramBuild my kitchen cupboard up into the scaled ceiling also on the side wall, my wife needs a ladder to access them though

Yes, my wife likes the tall cupboards because it means she doesn't have to dust the top and we can't collect junk on top. But she has to call me to access the top shelf, or get some steps out.

Posted By: tonyyou should put the stuff in the high ones that never gets used

You spotted it! But at least the junk isn't so obvious.

FT

That page requires a subscription.

David

Most, but not all, subscription websites can be read by searching for the headline in google and clicking on the link. They want to be indexed so have a 'visible' version. Works or this

We have a double height atrium facing south with all glass walls and the great advantage is that there is no heating required on the first floor. It works; 200m2 house heated by a 9kW back boiler feeding thermal store keeps us at about 20 degrees through the year.

Posted By: Simon StillMost, but not all, subscription websites can be read by searching for the headline in google and clicking on the link. They want to be indexed so have a 'visible' version. Works or this

Well it might if we knew what the headline was?

djh, the headline is on the linked page. I searched for "Bell Phillips rises to minister's bungalow challenge" and the free version is available.

Simon
Put a ceiling fan in