New build, heat pump vs solar and part L compliance

lainatro

Hi all, new to the site.
Firstly thank you for all contributors as your input has been invaluable. I am about to embark on a journey to build a bungalow of 280 m sq. All is set.

Planning on a 150mm gap, filled with bonded beads and 50 mm dry line kingspan. A MHRV by Beam and then I am stuck.

Solar pannels (maybe thermomax with 300l cylinder with condensor oil system pumping to rads) I have been recommended this approach by many independent people.

But others have suggested heat pumps with underfloor heating.

I just find heat pumps still not convincing enough and would like some further advise as to pros and cons.

Startup value for UFH and heat pumps can be substantial and also the thought of low heat system in potentially ice cold condition doesn't give me confidence.

Plus Part L talks of 10kw/h/m2/year. will I pass this ?? does it matter?

Can someone give me some real stats as to whether heat pumps in 2013 is actually worth it despite being banned in swedan and all the poor UK residents having to fork out >2000 poiunds on electric bills despite being initially reassured that annual bills will be 600 max.

Is this just some wacky conspiracy that governments are holding hands with the energy industry.

Would love to hear your comments...


THX

Tommyboy08

lainatro wrote: »

Hi all, new to the site.
Firstly thank you for all contributors as your input has been invaluable. I am about to embark on a journey to build a bungalow of 280 m sq. All is set.

Planning on a 150mm gap, filled with bonded beads and 50 mm dry line kingspan. A MHRV by Beam and then I am stuck.

Solar pannels (maybe thermomax with 300l cylinder with condensor oil system pumping to rads) I have been recommended this approach by many independent people.

But others have suggested heat pumps with underfloor heating.

I just find heat pumps still not convincing enough and would like some further advise as to pros and cons.

Startup value for UFH and heat pumps can be substantial and also the thought of low heat system in potentially ice cold condition doesn't give me confidence.

Plus Part L talks of 10kw/h/m2/year. will I pass this ?? does it matter?

Can someone give me some real stats as to whether heat pumps in 2013 is actually worth it despite being banned in swedan and all the poor UK residents having to fork out >2000 poiunds on electric bills despite being initially reassured that annual bills will be 600 max.

Is this just some wacky conspiracy that governments are holding hands with the energy industry.

Would love to hear your comments...

Heat pumps were not banned in Sweden and those huge bills in England were not due to proper heat pumps,
What was banned in Sweden and is causing all the trouble in England and I've seen plenty of them here are Nibe's excuse of a heat recovery heat pump, it's basically a huge immersion, absolute joke of a thing,
For your size house and insulation level I would recommend an 8kw ground source heat pump would give you running costs of about €300 per year.

You would not have any problem with minus temps either as this will have no effect on system performance

dathi

hi lainatro there is a lot more to complying to part L than just the renewable,s contribution and yes there is a legal obligation to build your house to comply. have you had your house plans put through the deap software to see do you comply? the days of building of your planning application drawings are over,and you need a holistic approach to your building elements to pass.

fclauson

Couple of comments - read the well know construction magazine which focus on Passive houses here in ireland - I have written a couple of articals about this - also search this forum for notes I have made - Part L is the law - TGD Part L is the guidence to achieve it.

I live in an A1 Passive Certified house

HP - I use about 15Kw of electricity per day to heat h/w and heating - thats probably gone up to 18 or may be 20 with the snow & freezing conditions of on the ground today and will drop to 6 or 8 in the summer when I just have h/w to produce. I have gone for PV over solar thermal - reason to meet Part L - and you can still get good energy in the winter from PV but not from solar thermal - my christmas turkey was cooked for free !! but there would probably not have been enough energy to heat any hot water if it was solar theraml)

Your full fill cavity and internal insulaiton is NOT the way to go - read up on keeping all you insulation in one place and thermal mass - I have a 250mm full fill cavity

I was not convinced on HPs until I did the maths - Solar + Oil was actually MORE EXPENSIVE than a correctly sized HP plus PV to meet part L (I added extra PV because I wanted to move from A3 to A1)

My house sits at about 20 degrees with a slight variation across the rooms - no thermostats , one single open circuit - I am feeding in 28 degrees from the HP into the floor when the out side air temp is 0

I have attached a graph with the data - not the interesting lag in heat demand at the top right - although the weather has been getting cold it took a few days for the heat pump to NEED (due to the thermal mass of the building) to add in more heat

The formula show the trend lines across the whole time period - double the "x" figure to get approx Kwh so the heating is about 10.4Kwh/day and the hot water is about 8.2 Kwh/day

Tommyboy08

fclauson wrote: »

Couple of comments - read the well know construction magazine which focus on Passive houses here in ireland - I have written a couple of articals about this - also search this forum for notes I have made - Part L is the law - TGD Part L is the guidence to achieve it.

I live in an A1 Passive Certified house

HP - I use about 15Kw of electricity per day to heat h/w and heating - thats probably gone up to 18 or may be 20 with the snow & freezing conditions of on the ground today and will drop to 6 or 8 in the summer when I just have h/w to produce. I have gone for PV over solar thermal - reason to meet Part L - and you can still get good energy in the winter from PV but not from solar thermal - my christmas turkey was cooked for free !! but there would probably not have been enough energy to heat any hot water if it was solar theraml)

Your full fill cavity and internal insulaiton is NOT the way to go - read up on keeping all you insulation in one place and thermal mass - I have a 250mm full fill cavity

I was not convinced on HPs until I did the maths - Solar + Oil was actually MORE EXPENSIVE than a correctly sized HP plus PV to meet part L (I added extra PV because I wanted to move from A3 to A1)

My house sits at about 20 degrees with a slight variation across the rooms - no thermostats , one single open circuit - I am feeding in 28 degrees from the HP into the floor when the out side air temp is 0

I have attached a graph with the data - not the interesting lag in heat demand at the top right - although the weather has been getting cold it took a few days for the heat pump to NEED (due to the thermal mass of the building) to add in more heat

The formula show the trend lines across the whole time period - double the "x" figure to get approx Kwh so the heating is about 10.4Kwh/day and the hot water is about 8.2 Kwh/day

What square meter is your house?

BryanF

fclauson wrote: »

Couple of comments - read the well know construction magazine which focus on Passive houses here in ireland - I have written a couple of articals about this - also search this forum for notes I have made - Part L is the law - TGD Part L is the guidence to achieve it.

I live in an A1 Passive Certified house

HP - I use about 15Kw of electricity per day to heat h/w and heating - thats probably gone up to 18 or may be 20 with the snow & freezing conditions of on the ground today and will drop to 6 or 8 in the summer when I just have h/w to produce. I have gone for PV over solar thermal - reason to meet Part L - and you can still get good energy in the winter from PV but not from solar thermal - my christmas turkey was cooked for free !! but there would probably not have been enough energy to heat any hot water if it was solar theraml)

Your full fill cavity and internal insulaiton is NOT the way to go - read up on keeping all you insulation in one place and thermal mass - I have a 250mm full fill cavity

I was not convinced on HPs until I did the maths - Solar + Oil was actually MORE EXPENSIVE than a correctly sized HP plus PV to meet part L (I added extra PV because I wanted to move from A3 to A1)

My house sits at about 20 degrees with a slight variation across the rooms - no thermostats , one single open circuit - I am feeding in 28 degrees from the HP into the floor when the out side air temp is 0

I have attached a graph with the data - not the interesting lag in heat demand at the top right - although the weather has been getting cold it took a few days for the heat pump to NEED (due to the thermal mass of the building) to add in more heat

The formula show the trend lines across the whole time period - double the "x" figure to get approx Kwh so the heating is about 10.4Kwh/day and the hot water is about 8.2 Kwh/day

Francis do you think its relevant that you spent x on the passive house compliance/detailing/ calcs and x on experts to achieve conditions where your heat pump would work at the levels in your attached graph? I see many jump at heat pumps and new technologies but equally fail to see the holistic construction practices, time, expertise's and hence cost involved on design upfront.

brdboard

fclauson wrote: »

I have attached a graph with the data - not the interesting lag in heat demand at the top right - although the weather has been getting cold it took a few days for the heat pump to NEED (due to the thermal mass of the building) to add in more heat

The formula show the trend lines across the whole time period - double the "x" figure to get approx Kwh so the heating is about 10.4Kwh/day and the hot water is about 8.2 Kwh/day

Hi Francis, could you tell me how you are measuring the data on your graphs? I have an air to water heat pump and and am trying to record how much the heat is costing me. At the moment all I'm measuring is the ESB meter once a week, which is total elec for the house, and a reading from the hp which gives me separate readings for the number of hours it has been heating the water and the house, so not very scientific.

Tommyboy08

BryanF wrote: »

Francis do you think its relevant that you spent x on the passive house compliance/detailing/ calcs and x on experts to achieve conditions where your heat pump would work at the levels in your attached graph? I see many jump at heat pumps and new technologies but equally fail to see the holistic construction practices, time, expertise's and hence cost involved on design upfront.

Unless its a 5000sq/ft house or his heat pump is broken I can't see the benefits of his passive construction cost. I have heat pumps in 3000sq/ft houses with 150mm wall insulation, no hrv and running at 10kw hr per day, I'm pretty sure these houses cost about half to build and it looks like about half the running costs also,
With his insulation levels and assuming its about 3000sq/ft it should be costing him about €1 per day to run not €3
If that's passive then I'm superman!!!!!!!!!

fclauson

Tommyboy08 wrote: »

What square meter is your house?

359 sqm

fclauson

BryanF wrote: »

Francis do you think its relevant that you spent x on the passive house compliance/detailing/ calcs and x on experts to achieve conditions where your heat pump would work at the levels in your attached graph? I see many jump at heat pumps and new technologies but equally fail to see the holistic construction practices, time, expertise's and hence cost involved on design upfront.

BryanF - yes basically

this is the BIGGEST investment I will ever make - and I used the best brains in the industry - and gave each of them a hard time to ensure they told me the truth the whole truth and nothing but the truth

HPs work well in buildings which are designed for them

fclauson

brdboard wrote: »

Hi Francis, could you tell me how you are measuring the data on your graphs? I have an air to water heat pump and and am trying to record how much the heat is costing me. At the moment all I'm measuring is the ESB meter once a week, which is total elec for the house, and a reading from the hp which gives me separate readings for the number of hours it has been heating the water and the house, so not very scientific.

software off the HP - check with the manufacture or supplier

fclauson

Tommyboy08 wrote: »

Unless its a 5000sq/ft house or his heat pump is broken I can't see the benefits of his passive construction cost. I have heat pumps in 3000sq/ft houses with 150mm wall insulation, no hrv and running at 10kw hr per day, I'm pretty sure these houses cost about half to build and it looks like about half the running costs also,
With his insulation levels and assuming its about 3000sq/ft it should be costing him about €1 per day to run not €3
If that's passive then I'm superman!!!!!!!!!

Tommyboy08 - Part L 2011 is close to passive - did I spend more than then regs - yes (because they are miss guided and give erroneous data via DEAP)

when you say 3000sqft and 10Kwh - is that
a) for h/w and heating
b) keep the building at a constant 20deg

Tommyboy08

fclauson wrote: »

Tommyboy08 - Part L 2011 is close to passive - did I spend more than then regs - yes (because they are miss guided and give erroneous data via DEAP)

when you say 3000sqft and 10Kwh - is that
a) for h/w and heating
b) keep the building at a constant 20deg

Yes for hot water and heating, no solar or immersion
Constant 20 degrees with 2 degree night setback

Condenser

fclauson wrote: »

BryanF - yes basically

this is the BIGGEST investment I will ever make - and I used the best brains in the industry - and gave each of them a hard time to ensure they told me the truth the whole truth and nothing but the truth

HPs work well in buildings which are designed for them

HP's work well in most situations where a low temp distribution system is installed. In fact the difference in running costs is even more stark in average to poorly insulated houses.

The installer and their interpretation of what is a well designed geothermal install is where they fall down.

fclauson

Tommyboy08 wrote: »

Yes for hot water and heating, no solar or immersion
Constant 20 degrees with 2 degree night setback

Interesting - just looking at heating
the PHPP model for my build for this time of year is showing an average of around 38kwh/day
DEAP shows around the high 20Kw/h per day

with mine coming it at around 10Kwh/day then I am very pleased

it would be good to see the model for the building you are speaking about

Condenser

fclauson wrote: »

Interesting - just looking at heating
the PHPP model for my build for this time of year is showing an average of around 38kwh/day
DEAP shows around the high 20Kw/h per day

with mine coming it at around 10Kwh/day then I am very pleased

it would be good to see the model for the building you are speaking about

That means you're only acheiving an SPF of 3.8. I would regard that as fairly poor but inline with what I'd expect from an Air to water.

fclauson

Condenser - thanks - what would be the quick rule of thumb to get a COP from my numbers

and just to clairfy - all the numbers I mention are for the electricity in - and not a measure of output

Condenser

fclauson wrote: »

Condenser - thanks - what would be the quick rule of thumb to get a COP from my numbers

and just to clairfy - all the numbers I mention are for the electricity in - and not a measure of output

Find your manfacturers COP at a given rating. On the cooling side i.e A2 or A7 every degree above the rated temp would raise your COP by 2%, everything below would drop it by 2%. Same rule applies to condensing but in reverse. Every degree above drops 2% and every degree below increases COP 2%.

So if your system was rated a A2/W35 (European Standard) and the air temp was 4 and the water outlet 30 (A4/W30) then your COP would be up by about 14%. That doesn't allow for defrosts and immersions topping up hot water or killing legionella.

Thats why properly designed ufh systems are so important. Every bit as important as insulation. We have a system not far from you (ground source) running a COP of 7.8 and an SPF of 6.3 when DHW is taken into account. Its just an illustration of how variable these numbers can be depending on installer and application.

bamberie

Hi there

We are looking for some info regarding an air to water system from anyone who might have one fitted inn their home. Our home is 3,000 sq ft with UFH throughout. Each room is zoned and although we only have a few rooms switched on we are still burning a hell of a lot of oil.

The house is only three years old so the system is new. We were considering an air to water system with PV Panels to help cover the cost of running it. We know very little about either of these systems so any advice would be appreciated!!

Thankk you in advance.

Condenser

bamberie wrote: »

Hi there

We are looking for some info regarding an air to water system from anyone who might have one fitted inn their home. Our home is 3,000 sq ft with UFH throughout. Each room is zoned and although we only have a few rooms switched on we are still burning a hell of a lot of oil.

The house is only three years old so the system is new. We were considering an air to water system with PV Panels to help cover the cost of running it. We know very little about either of these systems so any advice would be appreciated!!

Thankk you in advance.

How much oil and why air to water?

bamberie

Hi Condenser,

Hard to tell but we have used 500 ltrs from the 3rd of Jan to 17th of February. This is quite common during cold winter months.

Our house is built on rock so ground work is a nightmare. Also we live on high ground so temp is usually a couple of degrees lower. Don't know if that would make a difference.

Also house is well insulated.

We have an additional 1,500 sq ft upstairs which we may never use but would be gr8 if whatever system we get would feed rads upstairs...

Condenser

bamberie wrote: »

Hi Condenser,

Hard to tell but we have used 500 ltrs from the 3rd of Jan to 17th of February. This is quite common during cold winter months.

Our house is built on rock so ground work is a nightmare. Also we live on high ground so temp is usually a couple of degrees lower. Don't know if that would make a difference.

Also house is well insulated.

We have an additional 1,500 sq ft upstairs which we may never use but would be gr8 if whatever system we get would feed rads upstairs...

If you could find out some info for me over the next few days, then come back here and post it and I will work out whats the best options for you and how much it will cost you to run if you did switch.

can you
1. find out exactly how much oil you burn per year (doesn't have to be perfect)

2. The insulation specs of your house

3. The minimum temp you can run your ufh at and still feel comfortable/make temperature (just turn down the mixer valve a couple of degrees per day until the heat isn't making temp)

4. If you have any idea of the burner efficiency (not essential)

You may have to switch the rads in order to make them work with a HP or they'll drag down the efficiency of the whole system and defeat the purpose. The heat is going there already so it won't affect your running costs too much.

bamberie

thats great..i will get that info for you. thanks a mill.

Tommyboy08

fclauson wrote: »

Interesting - just looking at heating
the PHPP model for my build for this time of year is showing an average of around 38kwh/day
DEAP shows around the high 20Kw/h per day

with mine coming it at around 10Kwh/day then I am very pleased

it would be good to see the model for the building you are speaking about

No model used, just worked out the heat losses from the U values of the insulation used and installed a properly designed underfloor system coupled with a very efficient heat pump, and as you can see from the figures it shows the difference between good ground source units and inneficient air to water units.

I'm not saying that you wasted your money going for an A3 build, I'm all for energy efficiency, it's my job to be, I'm just trying to point out to people trying to build on a tight budget that you can have the same heating costs in a build that is less than half the price if the heating system is designed properly and pretty straightforward insulation practices are used, no need to spend big on phpp software, ber accessors energy consultants, architects when a messer like me can get better results with a calculator and a pencil!!!!

fclauson

Tommyboy08 wrote: »

No model used, just worked out the heat losses from the U values of the insulation used

How did you calculate thermal bridges - specifically around thresholds and windows where you need to do a FRSI calc as per the regs?

...for an A3 build,

Ours is an A1

... ber accessors ...

But you have to have a BER cert to comply with regs ??

MOTM

fclauson wrote: »

How did you calculate thermal bridges - specifically around thresholds and windows where you need to do a FRSI calc as per the regs?

TB calcs not needed if you use the acds as is. Acds can be used to derive y factor of 0.08. Or can do simple calc based on acd Psi values detailed in tgdl appendices.

fclauson

agreed - BUT if you insulate you house better than the ACDs where calculated at then you can run into trouble. As you superinsulate any slight cold bridge gets exasibated (made larger) and the slightest cold surface will be a magnet for moisture

to play out how this works - in a house where the walls are at an ambient temp of say 12 degrees - then the risk of localised condesation are fairly minimal - when you raise the whole internal structure to say 20 - but leave one bit (due to weak thermal bridge) at say 16 you can create a spot where mould will rapidly occure.

We are see a lot of this type of issues where buildings are taking advantage of the grants which are available but are failing to put in place the correct ventalation to match the insulation

bit off topic - sorry for that - but Part L and its associated issues are a bit of a fav of mine

MOTM

fclauson wrote: »

agreed - BUT if you insulate you house better than the ACDs where calculated at then you can run into trouble.

I know.

fclauson wrote: »

- but Part L and its associated issues are a bit of a fav of mine

I know.

beyondpassive

bamberie wrote: »

Hi there

We are looking for some info regarding an air to water system from anyone who might have one fitted inn their home. Our home is 3,000 sq ft with UFH throughout. Each room is zoned and although we only have a few rooms switched on we are still burning a hell of a lot of oil.

The house is only three years old so the system is new. We were considering an air to water system with PV Panels to help cover the cost of running it. We know very little about either of these systems so any advice would be appreciated!!

Thankk you in advance.

Sound like it was designed with a calculator and pencil :-)

Its likely that the problem is not the fuel but the way the house is built.
1. The oil should not heat the underfloor directly, it would be a good idea to have a buffer tank. You could still retrofit this in.
2. Sounds like you have a room in the roof. These are notorious for being draphty, the eaves are always left open for ventilation and the insulation stops and starts at the knee walls. Airtighness will make for big improvements. You could also consider heat recovery ventilation in parallel with airtightening the house. I've a cousin in law who build a huge dormer in Carlow and they have to decamp to the ground floor every winter. He told me the house was packed with the best of insulation, but when i looked it was only 150mm fibreglass acoustic quilt, with open eaves. Its not the quantity or type of insulation that counts, its how you install it. Its only as good as its weakest point.
3. Your walls are not themally broken so your underfloor is heating the rising walls and gables. You;d need to externally insulate to fix this.

There are still people building like this and then telling homebuilders things like you're wasting money going for an A3.

Tommyboy08

fclauson wrote: »

How did you calculate thermal bridges - specifically around thresholds and windows where you need to do a FRSI calc as per the regs?
I'm not the ber assessor, I believe that's his job. I was just designing the heating system, naturally I made allowances for such thermal bridges and with my running costs as they are it looks like I got things right, just over 3000 kw/hrs for the year, hot water and heating


Ours is an A1
My apologies for that typing error,


But you have to have a BER cert to comply with regs ??

Yes there is a ber cert for the house, they got an A3.

RavenII

Tommyboy08 wrote: »

Heat pumps were not banned in Sweden and those huge bills in England were not due to proper heat pumps,
What was banned in Sweden and is causing all the trouble in England and I've seen plenty of them here are Nibe's excuse of a heat recovery heat pump, it's basically a huge immersion, absolute joke of a thing,
For your size house and insulation level I would recommend an 8kw ground source heat pump would give you running costs of about €300 per year.

You would not have any problem with minus temps either as this will have no effect on system performance

Banned in Sweden???? Ahem, I don't think so...they're still currently produced in rather large numbers too. They have their uses in the right applications, if they're fitted in the wrong kind of house it would be bad of course...basically they are for small, highly insulated & airtight houses...it has to sized so that the internal immersions are rarely used and the cheap compressor heat is all that's used. The 'trouble' in the UK was just that...they fitted the machines in badly insulated council houses.

pmac086

Tommyboy08 wrote: »

Yes for hot water and heating, no solar or immersion
Constant 20 degrees with 2 degree night setback

Just to ask if you are boosting ( night setback to plus 2 deg ) early morning to "grab" the last of the night rate electricity ?

Have installed Geo deep bore along with solar south facing windows and 2 x 12 KW wood burners and always tweaking the Geo to get it just right. The 20 c you are running on is grand but living areas are more comfortable @ 22 and bedrooms 18 , would you consider control stats to obtain this ?

Not looking to knock, just to share .
Cheers
Peter

fclauson

Remember with a thermal mass (mine is of the order of 38tonnes) you are not going to move that quickly - so my settings are based on flow/return temps with a heat curve based on outside temp
at 0C outside the flow is (27C) - I have one whole house zone 
times are 
00-> 6am - on night rate 
06->10am - off
10am -> 4pm - on (to use any PV which might be available) 
4pm -> 00 - off 
my heating bill is around €150 per annum (plus HRV running costs) for 350sqm
the water is around €200

mrsWhippy

Given that heat pumps are more inefficient at night time, is there any argument to not running it at night, even with nightrates? Or are you always going to make a saving by running it overnight?

Cheers

fclauson

You would need to calculate

run time at night @ 9c per unit & a reduced outside air temp
vs
run time in day @ 18c per unit

its probably going to amount to €20 per annum either way

air

Condenser wrote: »

We have a system not far from you (ground source) running a COP of 7.8 and an SPF of 6.3 when DHW is taken into account.

Would love to hear more detail on this.