With the current chilly weather, I'm mulling over the best (most
efficient) way to keep my place warm. I work (or rather did) from home,
so weekdays normally see me here pretty much all the time. Weekends I
may be away for the weekend, or again pretty much here all the time.

I have gas-fired CH, via combi boiler, no HW tank. I live in an old
(1880's) property (small hall off which toilet, bathroom, kitchen,
livingroom off which 2 bedrooms), the upper of two maisonettes.
Insulation in the roof, though not to all that high a standard. No
insulation in floor, so I get the benefit of heat from downstairs when
it's running. Double glazing throughout, one external door not d/g. I
have a CH temp control on the boiler (and separate one for HW). It's a
non-modulating boiler. Property is quite large for room sizes but
sloping ceilings help reduce actual volume, and the rads are well sized
for the rooms. No TRV's but programmable room stat located in the hall.

The wall construction is somewhat unknown. I suspect brick for some
walls, either brick or brick/timber/lathe&plaster construction for
others - it's possible they're just timber/lathe&plaster throughout a
lot of the walls but not drilled into them to find out. Internally
everything apart from kitchen broom cupboard is drylined/plasterboarded
due to condensation/damp being a problem previous to my occupancy.

I'm not about to start adding insulation/upgrading
doubleglazing/replacing front door etc, so suggesting I stop more of the
heat from being lost in the first place *isn't* a useful OR valid
suggestion no matter how well-founded you think it might be.

Now, after all that background, the question. Since I'm not out all day
at work, I'm not sure what the most efficient way of heating the place is.

Should I:

Turn the boiler temp down, and keep the room stat at a fairly constant
setting and just a couple of degrees cooler at night, so that the system
is circulating fairly warm water around on a more frequent basis (on the
basis that eventually the heat lost from the house will equal the heat
the boiler is putting in near enough, with the CH running for long
periods with less frequent firing of boiler).

This would presumably avoid having to shove heat back into the walls etc
during the heat-up phase in the mornings.

Or:

Turn the boiler temp up, and set the room stat to drop significantly
overnight, with a blast of heat in the morning, then lower level during
the day, then another blast of heat in the evening. This means the
place will have cooled down significantly overnight, and the boiler will
be working hard to get the place back up to temp in the morning, it'll
cool slightly again during the day (I just wear jumpers cos it's easier
to regulate my heat with clothes depending on what I'm doing than it is
to turn the heating up and down all the time!), heat it back up during
the evening again before effectively switching it off over night.

This means the boiler's heating up the fabric of the house twice a day,
and then keeping the heat constant.



Now, I originally thought that it was easy to work out, and if the place
spent longer not needing to be heated (ie, overnight/during the day if
I'm wearing warm clothes) then it worked out more efficient to do the
latter, but I'm starting to wonder now.

Heat loss would be the same through the fabric, presumably it'll lose
heat faster when the difference between inside and outside is greater,
in which case keeping a lower overall temp would be more efficient (and
this is actually what I've done already, reduced the room stat by a
couple of degrees, which is fine for me).

So do I match the heat loss on a fairly constant level, thus keeping the
place heated to a fairly constant level, or do I let the outside suck
the heat out of it overnight, then heat the place back up and start
maintaining heat in to counter heat loss?

As you can tell if you've stuck with this to the end, I'm a bit confused
as to what the best thing to do would be. I've googled and googled both
in web and groups to see if this has been discussed and any evidence
found on the different ways to keep a place heated, and can find nothing
that really explains it, just lots of home energy efficiency tips. I
guess I'm looking for an article that explains the physics of heating a
home, and looks at the differences between the two ways of doing it.

Any replies will be much appreciated, and thanks for sticking with it if
you got this far.

Velvet