heat loss calculations

[AGT]

Approx 9kw for Victorian end terraced house 120m2 , some thermal upgrades, decent double glazing etc 60m2 extension
High ceilings etc, lath and plaster walls with decorative cornice that I won’t touch

[AE-NMidlands]

Approx 9kw for Victorian end terraced house 120m2 , some thermal upgrades, decent double glazing etc 60m2 extension
High ceilings etc, lath and plaster walls with decorative cornice that I won’t touch

We have a good cornice in our lounge and I dry-lined the outside walls...
I started by sawing the plaster horizontally below the cornice and stripping it back to the brick below the cut. Then battened out, foam packed, vapour barrier, plasterboard and skimmed.


I reckoned that a half-round moulding at the top of the wall below the cornice would look right - as from below you can't see that it is actually just below a horizontal step back towards the wall. What I did find out was that so-called half-round mouldings are actually a lot less than that, I had to get broomsticks and bandsaw them to get true half-rounds.

[spread-tee]

Is it difficult to work this all out for the whole house or do you need to be a heating engineer to get your head around it all?

I have all my room dimensions and btu's needed to heat each room.

Hallo mate, It doesn't have to be complicated at all really. Back in the year dot we used to size up a system by calculating a room volume in Cu Feet, multiply that by 5 and that was an individual heat requirement for the room in BThUs . Do the same for all the rooms , add together and there was your total heating requirements, 60.000 to 80.000 BThUs was pretty standard 3400 BThUs is more or less a kW

Then we got a bit more technical and used a Mears Calculator, which allowed for two external walls in a room, or excess window areas for example,
and the results were broadly similar.

Sometimes customers wanted a full heatloss calc based on all the elemental U values, or to get an M & E engineers report for heat loss, and the results were ...........broadly similar.

Nowadays it is somewhat less important because boilers are very much better at modulating to quite low power outputs, and if you ask your self "do I mind if the rads are slightly oversize?" If the answer is no, it all gets very simple IMO.

As others have said draught proofing and insulation is the hard bit.

Desp

[Richard77]

Is it difficult to work this all out for the whole house or do you need to be a heating engineer to get your head around it all?

I have all my room dimensions and btu's needed to heat each room.

Hallo mate, It doesn't have to be complicated at all really. Back in the year dot we used to size up a system by calculating a room volume in Cu Feet, multiply that by 5 and that was an individual heat requirement for the room in BThUs . Do the same for all the rooms , add together and there was your total heating requirements, 60.000 to 80.000 BThUs was pretty standard 3400 BThUs is more or less a kW

Then we got a bit more technical and used a Mears Calculator, which allowed for two external walls in a room, or excess window areas for example,
and the results were broadly similar.

Sometimes customers wanted a full heatloss calc based on all the elemental U values, or to get an M & E engineers report for heat loss, and the results were ...........broadly similar.

Nowadays it is somewhat less important because boilers are very much better at modulating to quite low power outputs, and if you ask your self "do I mind if the rads are slightly oversize?" If the answer is no, it all gets very simple IMO.

As others have said draught proofing and insulation is the hard bit.

Desp

Thanks spread-tee

I used the calculator on the link below to work out each room.

https://www.cityplumbing.co.uk/heat-loss-calculator

Ended up with a total of 91042 btu and 26674W.

All the rads were sufficient for each room by a decent margin. Shame the walls are as useful as a wet paper bag with respect to keeping the cold out and the heat in! I really do need to go round with this thermal imaging camera to find all the easy to fix draughts and gaps.

[nowty]

I did my own heat loss calculation a few years back before I upgraded the windows, its not that difficult, you just need a tape measure and a list of U values for your house structures.

[AGT]

Approx 9kw for Victorian end terraced house 120m2 , some thermal upgrades, decent double glazing etc 60m2 extension
High ceilings etc, lath and plaster walls with decorative cornice that I won’t touch

We have a good cornice in our lounge and I dry-lined the outside walls...
I started by sawing the plaster horizontally below the cornice and stripping it back to the brick below the cut. Then battened out, foam packed, vapour barrier, plasterboard and skimmed.


I reckoned that a half-round moulding at the top of the wall below the cornice would look right - as from below you can't see that it is actually just below a horizontal step back towards the wall. What I did find out was that so-called half-round mouldings are actually a lot less than that, I had to get broomsticks and bandsaw them to get true half-rounds.

Sounds like you. Nailed that solution,

[AE-NMidlands]

Sounds like you. Nailed that solution,

Actually I just stuck it on! (Groan...)

[knighty]

Is it difficult to work this all out for the whole house or do you need to be a heating engineer to get your head around it all?

I have all my room dimensions and btu's needed to heat each room.

https://heatpunk.co.uk made it really easy

they give you toal numbers and numbers for each room too

[knighty]

more details (I shouldhave had these at the start!

floor area is about 218 square meters (2350 sqr feet)

high cealings, 2.1m (10ft) downstairs, 2.75m (9ft) upstairs

mix of single and double glazing

I guess my shock is, that I thought with good underfloor/loft/ewi I'd be able to bring the numbers right down low

[richbee]

more details (I shouldhave had these at the start!

floor area is about 218 square meters (2350 sqr feet)

high cealings, 2.1m (10ft) downstairs, 2.75m (9ft) upstairs

mix of single and double glazing

I guess my shock is, that I thought with good underfloor/loft/ewi I'd be able to bring the numbers right down low

That is quite a property
I guess your 218 square metres is just the ground floor size?
From a heating calculation point of view, think you need to consider upstairs & downstairs separately, so more like 400 square metres, which maybe explains the high heat loss, with high ceilings too - good luck!