# Heating system for new build



## Dawn Run (25 Nov 2013)

Apologies if this is the wrong forum

Just looking for some general advice. I'm at the design stage of a new build - a 4 bed dormer bungalow in a rural setting.
 Should I go for underfloor heating or rads ?    Oil, gas or geothermal ? Is solar panels worth the cost re. pay back time etc. ?  What is your experience of these. Is the passive house system worth the extra initial cost outlay ?
Anyone on here built a timber framed house in the last 10 years...would you recommend it ?
Sorry for all the questions but I'm new to all this... when it comes to engineers and architects, they seem to be a 'click' who try to make the most simple of matters very complicated and therefore expensive.....to maxamise their own fee no doubt !


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## Buddyboy (25 Nov 2013)

Don't take this the wrong way, but your first port of call is the search function above.
All these questions have been covered many times before.  Read through the various threads and then you will get a lot more informative responses to specific questions.

And just to throw something else in, don't mix up heat generation method (oil, gas, electric) with heat distribution method, (rads, underfloor etc). They are apples and oranges, for example, you can have oil generated heat source, and use rads or underfloor. Similary you can have geothermal and have (specific large) rads or underfloor.

I forsee a lot of reading in your future.

Regards,
Corkboy


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## lowCO2design (27 Nov 2013)

Dawn Run said:


> Apologies if this is the wrong forum
> 
> Just looking for some general advice. I'm at the design stage of a new build - a 4 bed dormer bungalow in a rural setting.


the decision is in part a personal one, but there is a requirements to provide a % of renewables with any new build. so the decision should be made in conjunction with your provisional BER assessment & architect


> Should I go for underfloor heating or rads ?
> Oil, gas or geothermal ?
> Is solar panels worth the cost re. pay back time etc. ?
> What is your experience of these.
> ...


you've asked six huge vague questions which are quiet complicated and require personnel input, i suppose thats why you would need to go to architect, but no doubt their  only after your money, but you could  easily not bother with them and take advice on building your house from the  internet  have you considered reading around on the forum first before slating the professions who are on here giving free advise? 

your choice - ufh suits certain technologies that provide low temp constant heat
geo-thermal is expensive - oil & gas costs will only go one way
yes , but it need to be considered in conjunction with you homes demands/occupant lifestyles (you are aware its only good for hot water and not heating?) solar is unfortunately often only part of the renewable requirements of a new build - meaning on its own it may not be enough to meet part L of the building regs
each renewable technology has its pros & cons - I'm a fan of log gasification boilers assuming you can source wood and store it. at the moment heat pumps are popular but their not long in Ireland, meaning their lifespan is unproven. with all heating systems people tend to ignore the most important thing*: First Reduce      energy demand (build air-tight, insulate lots, ventilate right) & Increase      energy efficiency. Lastly      introduce low carbon energy solutions. (ie heating systems)*
i think so*,* but im a passive house designer *-* you know current regulations are quiet close to the PH standard, except for the air-tightness  requirement which is 7+ times better and thermal bridge attention to  detail. id suggest whether you care for the PH standard or  not you should go and visit one of them and use the principles - for  example orientating your habitable rooms south (at the sun) etc
i have designed and built timber homes and would recommend them as a more sustainable means of building a home than block. the concrete industry has us brain washed in Ireland so timber construction has a long way to go. on paper timber can be more expensive but its speed of assemble can get you water tight much quicker.


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## dgeers (2 Jan 2014)

Hi 
We have completed a new build with block ( we went through various building systems) , cavity insulation and internal insulated plasterboard +  triple glazing throughout the house. heating upstairs and downstairs is UFH + airsource heatpump that does hot water and heating and we have a heat recovery ventilation system. we have a small woodstove in the house as well
As LowCO2design points out, insulate the house properly. With the mild weather the heat requirements are modest at best with some solar gain.( we never build to be passive). get the proper information , we have spend money to save money we discussed the plans with the architect and the engineers and the external "experts" to get to an informed decision 

A few things that I have learned spend money on the stuff you cannot change easily, we spend a big chunk on the windows and heating system to get that right. ( second chunk was the kitchen). don't forget you are building your house not a technical experiment  ;o} . Include if you can an "plantroom" adjencent to the house all our technical gear is in there . Best thing so far is the Heat recovery the house is pleasant and ventilated  without windows and doors need to be opened.


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## lowCO2design (2 Jan 2014)

dgeers said:


> Hi
> ...new build with block..... cavity insulation and internal insulated plasterboard ......
> As LowCO2design points out, insulate the house properly. .......


please note this is not an insulation approach I would recommend.


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## Jetblue (2 Jan 2014)

Hi dgeers,

Can I ask what type/manufacturer of Heat recovery + ventilation you have used?

JB


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## theReel (2 Jan 2014)

lowCO2design said:


> please note this is not an insulation approach I would recommend.



Can I ask lowCO2design why this is not an approach you would take? 

I plan on filling my 100mm cavity and then using 75mm insulated plasterboard on all external walls and on the ceilings combined with insulation between the rafters. Similar to the approach you say you would not recommend - which is why I am curious.


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## dgeers (3 Jan 2014)

So am I lowCo2design, nevertheless I'm happy on what I have at the moment not going to change it now . We lived in 3 rental properties over  4 years, money sucking / freezing /breezing houses and moved in our house comfortable and happy that is the main thing 

There is a lot of knowledge on the boards.ie but in the end its your own descision. your own budget, your own house..  

HRV is Genvex... ( happy with it, not going to change it either )


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## lowCO2design (3 Jan 2014)

theReel said:


> Can I ask lowCO2design why this is not an approach you would take?
> 
> I plan on filling my 100mm cavity and then using 75mm insulated plasterboard on all external walls and on the ceilings combined with insulation between the rafters. Similar to the approach you say you would not recommend - which is why I am curious.


assuming block is all that one the cards: 200/300 wide cavity with bead fill, or to a lesser extent 150 cavity full fill rigid & lesser again external wall insulation

this has been covered and discuss elsewhere so in brief, if you dry-line:


you create two insulation zones with possibility of interstitial condensation between them often behind the dry-lining
you create further problems for electrical services + fixings with dry-lining in kitchens etc
you loose the thermal buffer (thermal mass) that block provides
but mainly you create a large width linear thermal bridge everywhere the external walls meet an inner wall, floor & ceiling. (ie where the dry-lining is broken by partition walls which if the surface temperature is lower that the internal RH due point will cause surface condensation possibly leading to mould (especially in corners behind furniture/wardrobes etc.
+ where will the air-tightness zone be? ie are you plastering the inner walls before dry-lining? how will you seal AT tapes to windows, floors along ceiling etc


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## lowCO2design (3 Jan 2014)

dgeers said:


> nevertheless I'm happy on what I have at the moment not going to change it now


no probs 

(you were intimating I was advocating a certain wall build-up, that i would never specify for the reasons outlined above)


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## theReel (14 Jan 2014)

Thanks for taking the time to reply lowCO2design, it is much appreciated.  The points you raised are all the issues that are giving me sleepless nights at the minute.

My foundations where put down 6+ years ago and then due to the joys of negative equity I was unable to build until now.
The foundations where built with block in mind and only allowed for a 100mm cavity.  I am currently researching the most effective way to enhance the insulation of the house and make it as airtight as I can - I am not necessarily after passive standards but want to do the best I can. Even considered widening the foundations but this would be expensive.

So far the best I have come up with is:
100mm cavity pumped with poly beads, 
150mm in the floor (I would do 200 but I am restricted height wise), 
60mm Insulated plasterboard dabbed to the inside leaf of all external walls - insulation turned in at all windows/doors and all joints and edges taped, 
Warm roof approach using spray insulation from cavity to ridge and finished with insulated plasterboard again.


On your points – 
1.    I have no solution for the possibility of condensation between zones and I am unsure if this is a serious risk or a slight concern.
2.    I will have to discuss fixing issue with the builders (especially the kitchen) other services I intend to chase into the wall, pull through the insulation and seal as best as possible.
3.    It is unfortunate but there is not much I can do about the concrete thermal mass
4.    I am not an expert on thermal bridges but I was hoping this may not be as serious an issue as when dry lining a solid external wall as there will be a 100mm cavity insulation gap between those walls – so the temp difference may not be too big.  I am also installing HRV which I hope will help prevent any condensation.
5.    I cannot think of an efficient way to implement an Air tight zone on the walls – considered batons and spray but not sure it would be worth the expense and extra inches out of space. I was hoping taping the plasterboard as best as possible will give me a reasonable level of air tightness but I have no idea how effective this approach is.

If anyone has any suggestions on a better way I could improve the insulation/air tightness considering my position I would gladly listen.


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