electric ufh??

L driver

Hello,
I'm a bit confused with heating/hot water for my new build and wonder if anyone can advise from their experience. Here are my build details;
Roof 0.12 w/m2k
wall 0.139w/m2k
floor 0.12w/m2k? (p/a 0.44, 160mm eps)
windows 0.84 w/m2k
no figure on airtightness yet, but will be low.
I'm wondering about using electric ufh cables throughout the house. wet ufh seems to be expensive for a well insulated house although it is suitable for solar, the best free energy. I have h/core and I wondering whether to put insulation under screed, will the h/core radiate the heat up without the insulation?
Also regarding dhw, would a small cyclinder be efficient heated with oil, or a bigger stratified connected to wet ufh?
As you can see I'm no expert, totally out of my depth. All opinions and experience are welcome

L driver

Anyone out there!!

heinbloed

Since there is a demand for thermal energy you should figure out how much that is. Only after the demand is clear the most suitable method of supply can be chosen.
For under floor heating a good perimeter insulation is a must.

Contact an energy advisor, a heating engineer or the like, they would be able to give you a guaranteed calculation sheet showing the actual or expected demand and a few suggestions on economical supply.

L driver

Thanks HB
energy demand in region of 25kWh/m2/yr. I am wondering if ufh with oil, gas or electricity is suitable, or would a st array be plausible . Looking for peoples experiences/knowledge.

heinbloed

energy demand in region of 25kWh/m2/yr

Now we need the peak load and the number of m2 and the m3 of space to be heated and the DHW demand and so on...

In principle any thermal energy source can feed an UFH.

There are solar houses which use free and renewable energy only. Check the www. for the recent Norman Foster solar awards, go onto their home page.
It was handed out in Switzerland recently, all winners in the various building categories produce more energy than they actually need. From the sun's light only.
These type of structures are not unique anymore, they make them now every day...Only the net-energy harvest is determing who will actually see a return on investment. Or who receives the next award.

As long as the home owner is willing to pay for buildings which do not produce capital (energy for sale) his short minded decision will have a long consequence of bills.

If you go for surface heating then include the walls as well, this allows a much lower surface/flow temperature and increases the response time.


http://www.sonnenhaus-institut.de/downloads/video/solarhaus-video-en.html


Two more links;

http://www.detail.de/artikel_swiss-solar-prize_26465_En.htm

and (in German only) this year's list of the Norman Foster solar award receivers:

http://www.swissolar.ch/de/news-von-der-sonne/news/article/?tx_ttnews[tt_news]=459&cHash=b82f5501a3

The percentage numbers at the end of the category winners list shows the energy generated with and for the structure.

ntpm

L driver wrote: »

Anyone out there!!

Lots of people out here..... but not too many understand your question:rolleyes:.
Too technical....
You need to speak to your architect/ engineer.
Get in a Main contractor/supplier to determine and design a complete package.

If you go with independent suppliers /contractors you will get one blaming the another one if things go wrong.

Generally :
with UFH go with WET. Electric on large scale is expensive to install and run.
UFH is best operated with renewable heat source eg.ground/water heatpump.
If going with Heatpump you might consider night rating/ dual tariff.
you can then supllement hotwater heating with electric elements.


Supplement heating for rads and hotwater with oil or gas. Depending on your location go with oil if not on natural gas(piped) (NG is cheaper that LPG/ bottle or bulk storage.

Definetly Solar Pannels for supplementary hotwater heating.

Solid fuel stove for localised heating is you have large open plan / living area. with back boiler for suplementary water heating.

All these supplementary heaing sources should be connected to a buffer tank. Therfore making the systems work more efficiently as one source may preheat another source.
Reducing overall heating costs.

L driver

ntpm wrote: »

Lots of people out here..... but not too many understand your question:rolleyes:.
Too technical....
You need to speak to your architect/ engineer.
Get in a Main contractor/supplier to determine and design a complete package.

Thanks ntpm
Sorry about the question, I didn't think it would be too technical. If I ask the engineer, the heating system will be oversized, self build and trying to iron every thing out myself. Posters with similar build types might offer their experience.

If you go with independent suppliers /contractors you will get one blaming the another one if things go wrong.

Yes,totally

Generally :
with UFH go with WET. Electric on large scale is expensive to install and run.
UFH is best operated with renewable heat source eg.ground/water heatpump.
If going with Heatpump you might consider night rating/ dual tariff.
you can then supllement hotwater heating with electric elements.

I didn't think electric was expensive to install, thanks for that have you any comparision with wet ufh? As for a heatpump aren't they just too much money in a well insulated/airtight house and don't let HB see you advocate a HP:D


Supplement heating for rads and hotwater with oil or gas. Depending on your location go with oil if not on natural gas(piped) (NG is cheaper that LPG/ bottle or bulk storage.

Definetly Solar Pannels for supplementary hotwater heating.

Solid fuel stove for localised heating is you have large open plan / living area. with back boiler for suplementary water heating.


Again thanks. No rads though, isn't UFH more economical/comfortable? Can LPG be bought cheaper in bulk, is it not cleaner than oil or NG. I would argue that a stove should be a room heater only.


All these supplementary heaing sources should be connected to a buffer tank. Therfore making the systems work more efficiently as one source may preheat another source.
Reducing overall heating costs.

Yes from all researches this buffer tank approach seems to be the way forward, look at the tanks in the links Heinbloed posted! The way forward no doubt. Thanks ntpm, I am open to correction on my replies, I am limited in what I know.

L driver

Sorry
I've replied in a quote, must have caffeine before engaging brain:)

L driver

Heinbloed,
Thanks for links, some great houses and % solar sufficient. But I do wonder about the capital outlay for some of the systems. You have your own solar thermal set up, how is that going, is it linked to a highly insulated buffer tank to be distributed to UFH. Scan homes over in Galway has a solar set up, but I think it's set up cost is very high. Like the idea of wall heating with low temp solar, want to be careful hanging pictures though. What sort of temp are people getting from their ST array in the last few weeks, would it heat a house (allowing for a passive/low energy house) with low temp wall and UFH?

heinbloed

The capital outlay of a solarhouse versus a certified passive house is better - if talking about total costs incl. mortgages, saved energy costs and usage of the structure This is aknowledged by many builders.
The sums shown at the homepage of the 'Solarhausinstitut' comparing identical buildings including the PHPP software(!) are showing a significant better capital performance of the solar house.

This better performance has to be seen under the fact that theses calculations are based on outdated solar data.
New climate observations comissioned by the EU comission has shown a significant increase of solar radiation within the last decade.

The new revised weather statistics show for Europe an average increase of 8% of solar radiation per year. Remarkably the highest increase is observed during winter time, for example Dublin up 30%. This makes all grandads calculation sheets ( "it can't be done in Ireland ....") go to the bin they belonged to from the day of publication...
It's the broad incompetence of the general Irish solar industry which is the reason why foreign ideas are leading in the Irish solar market, they did so from the beginning.
As you mentioned the solar house constructed by Scanhomes we should recognize that Scanhome is an experienced builder, doing certified PH since a long time. If they go Solarhause (as many 'old' PH builders on the continent as well) there seems to be some pudding in it...


Note as well that the avarage wind speed at low heights has decreased as well.

Here the new revised solar radiation data, you can search on the interactive map for your site:

http://re.jrc.ec.europa.eu/pvgis/index.htm

and the explanation why the old data should not be used any more:

http://re.jrc.ec.europa.eu/pvgis/PVGIS_new_features.html

Whilest oil runs out the sun gets cheaper every day. Only the energy you get delivered for free can make you independant. Buying pellets or electricity gets you nowhere into the green. Well, 'into the black' that is, in financial terms.


About my ST installation:

Yes, it works. The envisaged 50% reduction of bought in thermal energy (LPG for DHW and space heating) was met during the last heating season ('09-'10).
First heating season 2008-'09 39 % reduction,
last heating season 2009-'10 52% reduction.

This heating season the boiler is back on since 3 days.

The tank is well insulated by not high insulated.

For best performing seasonal storage tanks check the www. for vacuum insulated tanks. These are around on industrial scale since about 50 years and are aproaching the home market since short.

For the cheapest (price per stored volume) check for "foil tanks".

About nailing into heated surfaces:

There are thermo-luminant (?) foils available from your UFH/wall heating trader. These foils change colour when changing temperature and are fixed to a heated surface with a bit of tape. One sees the pattern of the heating element embedded in the surface like on a x-ray picture.
So no risk when hanging up pictures.


Ask your energy advisor for which software he goes when doing your energy balance, if they still use outdated weather data.
Ask your architect/civil engineer how he/she calculates the heat/cooling load.
Don't pay for unrealistic reports and calculations, they're worth nothing.



link about reduced wind speeds:

http://www.aecb.net/forum/index.php?PHPSESSID=h6orsoj07a6u55i6js4bvm0rd0&topic=2708.0