Notes from an eco house. (2025 Update)

I have external chimneys, which are blocked within the house. I assumed these would reduce heat loss..... ... perhaps not

Dave

That was in the 1980s

Thank you.

Many houses are built of 9" brick. When we say 'single brick' that is short for 'single brick WALL' as in no cavity.

Not wall as 'thick as a brick, only',

The heatloss is massive.

I don't understand this. Surely power loss through a wall is determined by the temperature differential, as well as the thermal conductivity. So you can't say "to the same temperature". Perhaps Roland is happier in a cooler house, or only warms specific rooms.

Also Roland makes the point about thermal mass. Averaging summer temperatures between too hot in the day, and too cold at night will save energy/ make the house more comfortable.

It is only very recently that heating prices have been significant, I suspect in the past it wasn't something Roland had to think too much about.

In message <vl6khg$3eugf$ snipped-for-privacy@dont-email.me, at 18:05:36 on Thu, 2 Jan

I'm sure I've seen a few rooms like that - often garage conversions. Then there's double-skin with the outer one brick and the inner breeze block, which don't seem to feature much in the tables of insulation value.

In message <vl6msi$3fc1o$ snipped-for-privacy@dont-email.me, at 18:45:37 on Thu, 2 Jan

Yes, my house has an original lean-to "extension" at the back. Originally perhaps a coal shed, and that was single skin brick until we had it converted to newly fitted utility room recently.

The previous owners used it as a utility room "as is".

In message <vl6pc5$3fpnl$ snipped-for-privacy@dont-email.me, at 19:28:05 on Thu, 2 Jan

My solid walls have no cavity but are 9" or 10" thick (plus an inch of plaster of course.)

In message <vl6pno$3figl$ snipped-for-privacy@dont-email.me, at 19:34:16 on Thu, 2 Jan

Depends where they are, the main fireplace in my house is in the wall between the kitchen and the next room (we call it lounge, but some might say 'dining room'). The second bedrooms fireplace was in that same internal wall. The lounge and above it main bedroom fireplaces are in an outside wall, but in effect that's a cavity wall with 9" solid brick, then air, then a single skin of bricks on the internal side.

There's no draught up any but the lounge fireplace, and that only when the woodburner installed there is running.

I disagree that they require removing.

Power loss is linear with temperature difference, yes, that's why the calculations have a Kelvin unit in them. But such calculations are typically done with standard indoor and outdoor temperatures - the coldest winter outdoor temps for your location and something like 21C for living rooms, 18C for bedrooms.

But if it's -3C outside then the difference between heating to 18C and 24C is 21K to 27K, ie about 28% difference in the loss calculation. That doesn't change the substance of the difference between materials.

It assumes a steady state, ie your boiler is set to a constant temp inside and a constant temp outside, so we're only considering conduction through the wall. Radiative losses, wind cooling and convection via air leaks aren't included.

It will smooth out daily peaks and troughs - this is important in summer especially (sun beating down at midday v middle of the night). But in the winter it's often cold for long periods (days/weeks), so any effect of the thermal mass is long gone (most decrement delays are on the order of hours).

Unless I suppose you live in castle with metre thick walls, although those tend to be draughty.

The model in the past was you'd just burn a coal fire all day long (later electric or gas), and it didn't matter too much about the energy efficiency of the house because you parked yourself in front of the fire. When you start thermostatically regulating the temperature then you start to notice the thermal losses.

Theo

That describes the almost every cavity wall since about 1965. I expect that's where you'll find them in the tables.

Theo

They are broadly similar to brick.

If you look it up

Since the 1950s

Breeze block being coal ash reprocessed.

Lightweight concrete block is a bit different

As an interesting factoid I worked out that a castle with 2 meter thick stone walls would meet modern heat loss regulations.

Its known as a single brick wall

Because there are not two walls

Large thermal mass means that you have to run heating continously as the house will take hours to warm up if toy just have the heating on when you get home from work etc.

It is less than ideal in a frequently unoccupied house

In message <vl6qde$3fkar$ snipped-for-privacy@dont-email.me, at 19:45:50 on Thu, 2 Jan

Thanks the vote of confidence, can we all please be kind to one another?

Loft insulation should have an effect on the heat loss through any gable wall whose inner surface is inside that loft. If you disagree, please show your working.

The only wall that matters is the external one in the lounge, because that's the only room we heat to any extent**, other than the new extension kitchen/diner leading off it, which has extreme insulation and hardly needs any overt heating.

The lounge is about 4m wide, with an average size double glazed window in it. So roughly 4m wide x 2.5m high, less a window that's 1m wide and

(4x2.5)-(1x1.5) = 8.5 sqm.

Your calculation above suggests total heat loss of 8.5x 2016/(5x8) =

** upstairs hall, and 2nd + 3rd bedrooms have non-functioning rads, which we've not fixed, and main bedroom has one rad turned down to achieve maybe 16 degrees. Bathroom has a waterfilled towel rail. Downstairs all has one rad and the thermostat, set to 18 degrees.

Yes - our Rayburn was on 24x7 in the winter - it heated the water too. I remember it being installed circa 1950. No more chimney fires after that. My job was refilling the coal scuttle with coke.

And yes, the delivery men really did say "Where d'ye wannit, Guv?" as it was also my job to show them where.

Is it possible that in Roland's case there is no actual cavity?

In message <vl8km8$3sqfa$ snipped-for-privacy@dont-email.me, at 12:20:24 on Fri, 3 Jan

I don't care what temperature the walls are, it's the air which matters. Not a great user of electric fans, but a wood burner with after-market fan warms a room up quite quickly.

I'm sort of retired now, but before that I used to work from home.

That's one reason why it was nice to have a cool house in the midsummer heat. (It's odd how the solid walls seem to have a diode in - you claim they leak outwards like a sieve, but 35 degrees outside doesn't appear to leak into the house).

In message snipped-for-privacy@mid.individual.net>, at 12:34:08 on Fri, 3 Jan

The walls in the main house have no cavity, but the new kitchen/diner extension does, having been built to very latest specification. Which included excavating the old floor and putting down lots of insulation there too.