My heads away with so much build stuff rushing about in the mush of my brain.  Just wanted to sense check my thoughts.  I am using @JSHarris heat loss spreadsheet which is a great job.  When people quote their calculated heat loss is it this field that they refer to (Total heat loss)?

 

Good question, I’m also wondering the same thing! Hopefully someone will have the answer, where is @JSHarris?

Further down, there is a section "Heat Loss versus outside temperature"

 

I use the worst case figure in the right hand column, when there is 30 degree between inside and out (i.e -10 outside and +20 inside)

@ProDave so mine is 5181 so this saying my house has a daily heat requirement of 5.2kWh not considering any hot water demand? Am I correct?

1 minute ago, vfrdave said:

@ProDave so mine is 5181 so this saying my house has a daily heat requirement of 5.2kWh not considering any hot water demand? Am I correct?

It's saying then when it is -10 outside and you want to keep it at +20 inside, then you need a continuous 5.2Kw of heat going into the house.

 

So if you maintain that temperature all day and night, it will use 124.8Kwh of energy per day.

 

To put this into perspective, ny own house has a worst case of 2.2KW in the same situation, so 52.8KWh per day, but that will be provided by a heat pump with a COP of at least 3, so will use 17.6KWh of electricity

On 03/05/2018 at 19:41, vfrdave said:

@ProDave so mine is 5181 so this saying my house has a daily heat requirement of 5.2kWh not considering any hot water demand? Am I correct?

 

@vfrdave Is your's a newbuild Dave to passiv-ish stds or a renovation?

 

I've just completed my heatloss calcs and I have ended up with 4799W (-10 outside; 20C inside) which is a lot higher than I was hoping (with 300mm insulated slab, EWI, 3G windows, SIPs). So now looking at what other areas I can improve on to maximise efficiencies (using up all my leftover celotex where I possibly can).

 

Let's just be grateful that the OAT isn't often -10C!

Edited May 7, 20188 yr by oranjeboom
Distinguishing which Dave. Too many Dave's here!

@oranjeboom  How big is your house? Bear in mind the original spreadsheet was for a simply shaped and modestly sized house, so the fact your heat loss figures are a lot more isn't of itself anything to worry about.

@oranjeboom mine is a new build traditional block build and no won't be passive standards. It is also a fair bit bigger footprint than Jeremy's.

6 hours ago, Stones said:

@oranjeboom  How big is your house? Bear in mind the original spreadsheet was for a simply shaped and modestly sized house, so the fact your heat loss figures are a lot more isn't of itself anything to worry about.

 

@Stones 174sqm and it's an uneven H-shaped building. Not too worried, just trying to get the right level energy in there for the winter months for the UFH and DHW, i.e. don't want to fork out for a 12kW ASHP if I can get away with an 8kW machine (30% oversized for January temps when I'll be needing 70kWh per day for space heating and DHW. Likewise, I don't want to go in undersized either! Funnily enough, just been reading the thread you started o ASHP sizing: here.

 

3 hours ago, vfrdave said:

@oranjeboom mine is a new build traditional block build and no won't be passive standards. It is also a fair bit bigger footprint than Jeremy's.

 

Thanks Dave.

When using the heat loss calculator, do you need to use different total house volumes for the attic space dependent on if it's a warm or cold roof?

Would anybody have a copy of the xl file.  I can't seem to find it and am just looking into whether to invest in an ASHP or gas boiler for my sips - based on the home requirements and budget.  I'd really appreciate this.