DHW and Backup heating spec for PH

beyondpassive

sas wrote: »

Well that's just fabulous!

This is doing little to counter my "Don't build a passive house" stance.

Well all things being said, you will have a certified Passivhaus at the end of the day, so doesn't that achievement put you in a very exclusive Passivhaus club. I bet you'll soon be having fondue parties in leaderhosen with your new Passivhaus Institute amigos, while we stand jealously staring in through the low E treble glazing, warming our freezing fingerless gloved fingers around an old tar barrell and confusing ourselves with 3 port motor driven thermostatic variable speed valves and the like.

beyondpassive

fodda wrote: »

Reading this again gets even more confusing.

The dark art of plumbing

fodda wrote: »

If you want to dump excess heat why not have a larger tank?

A sunny week in June July would fill a swimming pool, sonnenhouse type tanks of 20,000 litres overheat the house and it dificult to make interseasonal stores viable.

fodda wrote: »

If the house is passive design, why so much heat?

Because the renewable requirements of Part L require 10kWh per m2 per annum, thats 3,000kWh of solar panel for a 300m2 house. Such a system on a summer day could have heated the tank to 95 degrees by 10am in the morning with a 300l cylinder.

fodda wrote: »

How many kw are these 90 tubes going to give you per year and what is the total cost of their installation with tank?

3,200 kWh or so depending on location, angle and the utilisation, Payback is similar to the life of the tubes. Best to see the house and heating/ ventilation as a whole system rather than isolating components.

see Andy Wilsons article for solar system design
http://www.sustainability.ie/solararticle.pdf

fodda

So basically there is a passive type house supposed to require little heating and the mother of all solar tube hot water heating systems that on a good day will be enough for a housing estate.

Being as there really is no such thing as free heat (cost installation etc), then why not just have a wood powered boiler and large thermal store/tank and be done with it?

beyondpassive

fodda wrote: »

So basically there is a passive type house supposed to require little heating and the mother of all solar tube hot water heating systems that on a good day will be enough for a housing estate.

Being as there really is no such thing as free heat (cost installation etc), then why not just have a wood powered boiler and large thermal store/tank and be done with it?

Its not a Passivhaus requirement for 70 plus tubes for big houses it's a DOHELG part L compliance issue.
How is a wood boiler or a pellet stove simpler than solar and fossil boiler? Are you a lumberjack or woodcutte by chance?
Solar panels won't give you much in December and January.

fodda

beyondpassive wrote: »

Its not a Passivhaus requirement for 70 plus tubes for big houses it's a DOHELG part L compliance issue.
How is a wood boiler or a pellet stove simpler than solar and fossil boiler? Are you a lumberjack or woodcutte by chance?
Solar panels won't give you much in December and January.

No but i have a big chopper;)

My example is a wood boiler be it log, pellet or chip is carbon neutral and ecological so fits in with the whole theme.

When used with a thermal store it can be used and the energy stored for when it is needed without frying the house inhabitants.

It is 24/7 365 days of the year whenever you want it can supply hot water.

It would hopefully be pretty maintainence free as unlike tubes etc

It seems a whole lot simpler than all this anyway.......and that was my reason for the suggestion.:)

superchip

at do-more
i went with a 6 inch pumped cavity,62mm kingspan slabs on all external walls and all downstairs ceilings with 8inches of rockwool between joists.i also went with a treble glassed windows with insulated frames.i would highly recommend them. im only getting to grips with the set up as its only just up and running 2 wks but i think its awesome so far

BryanF

fodda wrote: »

No but i have a big chopper;)

My example is a wood boiler be it log, pellet or chip is carbon neutral and ecological so fits in with the whole theme.

When used with a thermal store it can be used and the energy stored for when it is needed without frying the house inhabitants.

It is 24/7 365 days of the year whenever you want it can supply hot water.

It would hopefully be pretty maintainence free as unlike tubes etc

It seems a whole lot simpler than all this anyway.......and that was my reason for the suggestion.:)

I'm all for the log boiler, its certainly the solution for those that can source their own supplies. but will it meet the 2011 TGD part L requirements? maybe in a 'just to Buildings regs' home I'm not convinced, but I don't think it will in a PassiveH

fclauson

If you want to have some fun with you PHPP sheet

take the Heat Demand sheet and unlock it
at the top are two temps - cells d7 and d8

For Ireland this is the lowest average temp on the shortest solar day of the year - probably has something like
0.5 (temp on the cold sunny day)
5 (temp on the dark gloomy day)

not put them both to say -5 and then -10

check out your house heat demand figs - cell q84

Now passive house works well on Mr average - but on days when its not you need more heat

creedp

fclauson wrote: »

If you want to have some fun with you PHPP sheet

take the Heat Demand sheet and unlock it
at the top are two temps - cells d7 and d8

For Ireland this is the lowest average temp on the shortest solar day of the year - probably has something like
0.5 (temp on the cold sunny day)
5 (temp on the dark gloomy day)

not put them both to say -5 and then -10

check out your house heat demand figs - cell q84

Now passive house works well on Mr average - but on days when its not you need more heat

This stuff is facinating when you are a technophobe and are self-building with last century's technology:). Very shortly after starting at this game I have been disappointed in the fact that I didn't do more research and hire professionals that I didn't even know existed to help build a modern efficient house within my budgetary constraints .. all too late now though!! However I have been following with interest the many discussions which have taken place on this forum in this area and have always been amazed by the level of knowledge/expertise/experience people have in an area that the vast majority of building pros I have come across have no knowlwdge of and have no interest in acquiring this knowledge.

However, sometimes I feel that the whole theoritical nature of the heat demand/supply discussion gets difficult to absorb. Now when I hear that Passive Hse experts warning that heating systems designed according to Passive Hse stds will be undersized and the points being made here in relation to Mr Average weather I can't help wondering about people who are insisting on designing a heat system to meet very precise theoritical heat demand such as that described by Do-more here:

We are back to sledge hammers to crack nuts again! My total space heating and DHW demand that can't be provided by solar is approx. 5.7kWh/a. according to the rule of thumb sizing guide which you posted earlier I should be installing a 2000 litre thermal store and a 40kW log gasification boiler!

Yer gas alright!

Maybe the suggestion being made re: log boiler might be more appropriate than the theory might let one to believe. Anyway as I said before I'm just jealous but I continue to follow with interest these discussions and look forward to people who build to passive hse stds coming back and posting their real life experiences of their houses .. just to increase the jealousy levels to fever pitch:)

fodda

creedp wrote: »

We are back to sledge hammers to crack nuts again! My total space heating and DHW demand that can't be provided by solar is approx. 5.7kWh/a. according to the rule of thumb sizing guide which you posted earlier I should be installing a 2000 litre thermal store and a 40kW log gasification boiler!

Yer gas alright!

Maybe the suggestion being made re: log boiler might be more appropriate than the theory might let one to believe. Anyway as I said before I'm just jealous but I continue to follow with interest these discussions and look forward to people who build to passive hse stds coming back and posting their real life experiences of their houses .. just to increase the jealousy levels to fever pitch:)

The idea of a batch boiler is that it is used once every one or two days so are always larger than normal boilers..........gas alright:)

beyondpassive

Do-more wrote: »

My total space heating and DHW demand that can't be provided by solar is approx. 5.7kWh/a. according to the rule of thumb

Should this read 5.7 kWh per hour?

Do-more

beyondpassive wrote: »

Should this read 5.7 kWh per hour?

Should have been 5,700kWh/a!

The hourly rate is about 2.3kWh.

fclauson has made a very good suggestion regarding replacing the average climate data with the worst case scenario in order to calculate the peak heat demand for the house.

I've asked my architect to run the calculations again based on the coldest day in the last 6 years so it will be interesting to see what the result is when I get it.

I would stand by my claim however that the 40kW log boiler and 2000 litre thermal store suggested by the rule of thumb in fodda's link is overkill.

All of the solutions I am looking at so far are capable of delivering a minimum of 3 times the heat demand that the PHPP suggests and are considerable smaller.

beyondpassive's article on solar panels makes for useful reading as well!

The whole process of making a decision on a heating system does very much feel like going around in circles I just hope the circle keeps getting smaller!

fodda you will be happy to hear that in my continued research of wood pellet boilers I have found a number of combination boilers which can also burn logs as well as pellets, the cost is about €1000 more than the pellet only boiler which costs about €3,750 here but the problem is I would need at least 1500 litre accumulator capacity to accommodate the heat produced from one burn which pushes the budget even further, and more importantly I'll be divorced as the wife will have no room left in the utility!

BryanF

Do-more, didn't you discount the wood boiler sometime ago, spouting some US reports on air quality:D was that you?

fodda

Do-more wrote: »

Should have been 5,700kWh/a!

The hourly rate is about 2.3kWh.

fclauson has made a very good suggestion regarding replacing the average climate data with the worst case scenario in order to calculate the peak heat demand for the house.

I've asked my architect to run the calculations again based on the coldest day in the last 6 years so it will be interesting to see what the result is when I get it.

I would stand by my claim however that the 40kW log boiler and 2000 litre thermal store suggested by the rule of thumb in fodda's link is overkill.

All of the solutions I am looking at so far are capable of delivering a minimum of 3 times the heat demand that the PHPP suggests and are considerable smaller.

beyondpassive's article on solar panels makes for useful reading as well!

The whole process of making a decision on a heating system does very much feel like going around in circles I just hope the circle keeps getting smaller!

fodda you will be happy to hear that in my continued research of wood pellet boilers I have found a number of combination boilers which can also burn logs as well as pellets, the cost is about €1000 more than the pellet only boiler which costs about €3,750 here but the problem is I would need at least 1500 litre accumulator capacity to accommodate the heat produced from one burn which pushes the budget even further, and more importantly I'll be divorced as the wife will have no room left in the utility!

As i said early the idea with a "log batch" boiler is that it is preferably a "burn once" type boiler so is over rated? but the idea of a thermal mass/thermal storage/buffer tank is that it is a "heat battery" just waiting there for you to draw on it when needed.

Your wood pellet boiler is automatic so could burn whenever needed to top up the water storage so need not be as big a boiler output and programmed to come on very early morning and late afternoon? so supplying plenty of hot water for the house.

One thing though with storage tanks...........you will need at least 12" of insulation to stop heat leaking from it, so this again takes up plenty of room and a garage or purpose built boiler house is a must bearing in mind the height of them which can be over 9ft with insulation but you can get 2 smaller tanks instead which may be better for you.

As regards emissions, they are cleaner than almost anything else and wood is carbon neutral and eco friendly. The gasifying versions will meet some of the most stringent emission controls but cost a bit more because of the fan assisted and ceramic interior designs.

Do-more

BryanF wrote: »

Do-more, didn't you discount the wood boiler sometime ago, spouting some US reports on air quality:D was that you?

Just trying to keep fodda happy!

But yes, standard wood burners are banned in a number of municipalities here.

I'm waiting for confirmation, but from a chat with the local planners this morning my option of heating the house with an air to air heat pump is also out the window, as the new building regs here no longer permit air to air or air to water heat pumps in new builds due to energy efficiency concerns, it appears that the only heat pumps now allowed in new builds are ground source or exhaust air. But I'm waiting on confirmation as their may be an exemption for houses with low energy demands but my Swedish isn't good enough to figure out the subtly's of the regs. I'm sure that will be music to your ears!

Looks like my best option will end up a 20kW wood pellet boiler with a 750 litre accumulator tank, I might even forget about the solar panels and put in in UFH down stairs!

Did I mention something about going around in circles?

sas

So I've been pondering our situation....

Dec 1st is where it all comes together (or not). That's blower door day.

The detailing is all pretty much accounted for in the PHPP. The only measurable thing that's left is the airtightness. This is the only thing standing between me and a PH certificate to the best of my knowledge.

I'm also on a very tight timeline because herself is thoroughly fed up with how long this is taking. I can give max 1 week to get down below 0.6 if we are unsuccessful on the day.

If we fail and no cert will be forth coming, then my concern about running pipes through wall etc. diminishes. So we will forget about UFH downstairs and radiator out the entire house and add an oil\lpg boiler in the garage.

If we achieve the N50 0.6 ach the original plan is back in play.





SAS

Do-more

With the amount of effort you have put into your build sas I will be very surprised if you don't fly through your air tightness test.

Best of luck with it any case.

BryanF

Do-more wrote: »

Just trying to keep fodda happy!

But yes, standard wood burners are banned in a number of municipalities here.

I'm waiting for confirmation, but from a chat with the local planners this morning my option of heating the house with an air to air heat pump is also out the window, as the new building regs here no longer permit air to air or air to water heat pumps in new builds due to energy efficiency concerns, it appears that the only heat pumps now allowed in new builds are ground source or exhaust air.

interesting

BryanF

sas wrote: »

If we achieve the N50 0.6 ach the original plan is back in play.

good luck:) give us a detailed report on how you get on

fclauson

sas wrote: »

If we achieve the N50 0.6 ach the original plan is back in play.

SAS

You deserve to get this if anybody does - GOOD LUCK

Do-more

fclauson wrote: »

If you want to have some fun with you PHPP sheet

take the Heat Demand sheet and unlock it
at the top are two temps - cells d7 and d8

For Ireland this is the lowest average temp on the shortest solar day of the year - probably has something like
0.5 (temp on the cold sunny day)
5 (temp on the dark gloomy day)

not put them both to say -5 and then -10

check out your house heat demand figs - cell q84

Now passive house works well on Mr average - but on days when its not you need more heat

I got my architect to run this exercise for me to see what my peak load might be.

The only daily climate data I could find only went back to 2006 with the lowest temperature occuring in Jan. 2010 so I gave him a slightly lower figure than that.

The heat demand increased from 2328W to 2624W (approx. 12.7%)

I must say I was expecting a much larger increase than that and I now assume that the climate data that my PHPP is based on must be pretty valid.

We do benefit here from normally having very stable weather and as the house is right on the coast we don't tend to suffer the extreme lows in temperature that can occur further inland.

Thanks fclauson for the suggestion, unless I am interpreting it wrong, it does help to put the mind at rest that the basis for my house's PHPP calculation is reasonably sound I hope.

As a matter of interest fc what sort of an increase were you seeing?

creedp

Do-more wrote: »

I got my architect to run this exercise for me to see what my peak load might be.

The only daily climate data I could find only went back to 2006 with the lowest temperature occuring in Jan. 2010 so I gave him a slightly lower figure than that.

The heat demand increased from 2328W to 2624W (approx. 12.7%)

I must say I was expecting a much larger increase than that and I now assume that the climate data that my PHPP is based on must be pretty valid.

We do benefit here from normally having very stable weather and as the house is right on the coast we don't tend to suffer the extreme lows in temperature that can occur further inland.

Thanks fclauson for the suggestion, unless I am interpreting it wrong, it does help to put the mind at rest that the basis for my house's PHPP calculation is reasonably sound I hope.

As a matter of interest fc what sort of an increase were you seeing?

I'm out of my depth here so try to be patient:) Can I ask if this predicted heat demand is based on assumption that the house is maintained at a steady 20c? How would this be affected by members of household who complain that this is not hot enough for them and want it to be heated to 23 - 24c? This seems to be fairly common in that although 20c is a very comfortable (and healthy) temp it doesn't cater well for people accustomed to have their knees reddened by open fires for a few hours in the evening:). They are happy most of the time but want a serious ramp up for say between 8 and 11pm. I suppose this can be realtively easily achieved in a passive house with a stove but how is that accommodated for in the PHPP model?

BryanF

creedp wrote: »

I'm out of my depth here so try to be patient:) Can I ask if this predicted heat demand is based on assumption that the house is maintained at a steady 20c? How would this be affected by members of household who complain that this is not hot enough for them and want it to be heated to 23 - 24c? This seems to be fairly common in that although 20c is a very comfortable (and healthy) temp it doesn't cater well for people accustomed to have their knees reddened by open fires for a few hours in the evening:). They are happy most of the time but want a serious ramp up for say between 8 and 11pm. I suppose this can be realtively easily achieved in a passive house with a stove but how is that accommodated for in the PHPP model?

Its not really considered.. but then the assumption that people will need 23-24 degrees is ignored, as the phpp presumes such a high standard of building that, there is less of a need for radiant heat. this doesn't solve the physiological need:) and what i generally recommend is people go and visit such a home and see for themselves and speak to the owners

this demand for heating is usually associated with the type of houses we've grown up in - where as soon as the heat source is off the heat in the room is heading for the ceiling and the drafts are making you cold again.

beyondpassive

In PHPP You can set the heating set point for the year, for Nursing homes this is 22.5 degrees. Increasing the temperature from 20-22.5 degrees for the heating season adds about 4kWh per metre square to a build. However teh experience of most Passive Houses is that 19 degree fells like 23 due to less humidity and filtered air, radiant surfaces and better daylight.

creedp

BryanF wrote: »

Its not really considered.. but then the assumption that people will need 23-24 degrees is ignored, as the phpp presumes such a high standard of building that, there is less of a need for radiant heat. this doesn't solve the physiological need:) and what i generally recommend is people go and visit such a home and see for themselves and speak to the owners

this demand for heating is usually associated with the type of houses we've grown up in - where as soon as the heat source is off the heat in the room is heading for the ceiling and the drafts are making you cold again.

I think its the physiological need I am referring to here Im afraid. Its not uncommon for people of a certain vintage due I suppose to a great degree to what they have been accustomed to. I remember my uncle who is in his 70s complaining about the fact that his daughters new house was bloody freezing and she should put a roaring fire going in the stove despite the fact that the house was very comfortable at 20c. However, the problem is not exclusive to that generation and that's the problem for me. Hopefully becomming accustomed to the more gentle natural heat in modern more efficient houses will happen relatively quickly because otherwise the stove will be roaring regularly!!

fclauson

fclauson wrote: »

If you want to have some fun with you PHPP sheet

take the Heat Demand sheet and unlock it
at the top are two temps - cells d7 and d8

For Ireland this is the lowest average temp on the shortest solar day of the year - probably has something like
0.5 (temp on the cold sunny day)
5 (temp on the dark gloomy day)

not put them both to say -5 and then -10

check out your house heat demand figs - cell q84

Now passive house works well on Mr average - but on days when its not you need more heat

Sorry - should have said that also G8-to K8 or the row above (solar insolation) should be set to a low value (say 5,5,5,5,5) - so its a freezing foggy murkey day

Do-more

sas wrote: »

(b) Supplier of tubes is specifying a 1000 litre stratified tank for both DHW and backup heating. This would have all the necessary coils etc.

Hi sas, just wondering if you went for the 1000 litre tank or some other solution in the end?

sas

Do-more wrote: »

Hi sas, just wondering if you went for the 1000 litre tank or some other solution in the end?

Not there yet I'm afraid. That is the current plan however. If the stove and solar can't provide sufficient heat to it in winter, we'll be adding a condensing oil burner to compensate. House isn't on the natural gas line so oil is the cheapest fallback option.