DHW and Backup heating spec for PH

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.