My house has a climate of its own — and I’ve spent weeks spying on it.

Most people have a thermostat. I appear to have accidentally created a domestic climate laboratory.

What began as a simple question — “is my house actually good at keeping me warm?” — turned into a surprisingly rich experiment. The hall sensor, the living-room sensor and the outdoor sensor have been logging how the building responds hour after hour: how quickly it warms in the morning, how long it hangs onto heat, when one room starts behaving differently from another, and how much the outside weather really manages to influence life indoors.

After more than 130,000 readings, the house no longer looks like a passive box with radiators in it. It looks like a living thermal system with its own rhythm, its own habits and, frankly, a bit of a personality.

The living room is the comfort specialist. The hall is the sensible reference point. Outside is the nuisance constantly trying to drag everything back towards ambient temperature. Once you start looking at the three together, the story becomes surprisingly easy to read.

Three characters explain nearly everything.

🛋️ The Living Room — the cosy one

The living room is where the house stops being an engineering problem and becomes somewhere I actually want to sit. It is usually the warmest room, often climbing into the 21–23°C range even while the hall remains around 20°C. That makes it the best measure of comfort, but not always the best measure of the whole building.

Why? Because it can get extra local heat. When that happens, the living room creates its own microclimate. Its temperature can keep climbing while the hall has already flattened out. That gap is enormously useful because it tells us when the heat source affecting the living room is probably different from the heat source affecting the house as a whole.

🚪 The Hall — the sensible one

The hall is much calmer. It changes more slowly, reaches fewer dramatic peaks and behaves far more like the thermal backbone of the building. That makes it our best “how is the house doing?” sensor.

If the hall suddenly gains two or three degrees, I pay attention. If it sits almost motionless while the living room continues climbing, I pay attention again. It is not flashy, but it is a brilliant witness.

🌧️ Outside — the troublemaker

Outside temperature is the context for everything. A 20°C hall means one thing when it is 18°C outdoors and something completely different when it is 6°C outdoors. The colder it is outside, the stronger the temperature difference trying to pull heat out of the house.

That is why the outdoor sensor matters so much: it tells us how hard the building is being challenged at any given moment.

The house is consistently warmer than the world outside.

The living room is nearly 8°C warmer than outside on average. The hall is more than 7°C warmer. That does not prove perfect insulation, but it does prove that the indoor environment is being successfully separated from outdoor conditions.

What is especially interesting is that the indoor rooms do not move around as wildly as outside does. The weather can change quickly; the hall tends to shrug its shoulders and change much more slowly. That is thermal damping — the house smoothing out the weather before it reaches you.

Think of it like this: outside can throw a tantrum. The hall generally responds with a raised eyebrow.

The house wakes up, warms up, settles down and then slowly goes to sleep.

06:00 — the low point

The early morning is usually when the house has had the longest period with reduced heat input. The hall is often around 17–18°C. That is not freezing, but it is clearly cooler than the daytime comfort level.

Shortly after 06:00 — the house wakes up

Then the trace changes. The hall stops drifting and starts climbing. On strong recovery mornings, it can gain roughly 2–3°C in under two hours. That sort of acceleration is the first big clue that the main heating system has entered the picture.

07:30–08:00 — equilibrium arrives

The hall approaches roughly 20°C and the steep rise disappears. The room has reached the neighbourhood of its target, heat input reduces, and the line flattens.

Then the living room carries on

This is the clever bit. The hall has settled. The house is broadly warm. But the living room frequently keeps climbing. That is when the comfort zone becomes its own little world, often moving into the 21–23°C band while the hall remains near 20°C.

Evening — the balance changes again

Later, heat input reduces. The living room begins surrendering its extra temperature advantage and starts moving back towards the hall. The rooms converge. The whole house gradually transitions from active heating to stored-heat mode.

The boiler never confessed. The temperature curves gave it away.

The sensors do not directly record “boiler ON”. They do something more subtle: they record the consequences. That means heating events can be reconstructed from the fingerprints they leave behind.

Clue 1 — the hall suddenly rises

If a room that has been gently cooling suddenly begins gaining around 1–2°C per hour, energy is being added. Walls do not spontaneously decide to become warmer at 06:15.

Clue 2 — both rooms rise together

If hall and living room start recovering at roughly the same time, a whole-house heat source is the strongest explanation.

Clue 3 — the living room keeps rising after the hall stops

This is the giveaway for local heating. Once the hall is stable, continued living-room warming means a source is affecting that room disproportionately.

Clue 4 — a plateau suddenly becomes a decline

A room sitting steadily at 23°C and then beginning a sustained drop is telling us something changed. Heat input probably reduced or stopped.

Clue 5 — outside stays cold

If the indoor temperature is racing upwards while the outside sensor barely moves, there is no need to summon Sherlock Holmes. The heat is coming from inside the house.

The morning that made the whole experiment click.

Outside was only around 6.5°C. The hall was close to 17°C. Then, over about two hours, it gained roughly three degrees.

That rise is far too strong to explain with outdoor conditions. It is the thermal equivalent of muddy footprints leading straight back to the boiler.

And then, once the hall reached around 20°C, the pattern changed. The hall settled. The living room kept warming. That one morning gives us both stages of the system in sequence: first warm the building, then warm the comfort zone.

A falling living-room temperature is not the same as heat disappearing outdoors.

If the living room is hotter than the hall, some of its energy flows into the hall and into cooler internal walls, floors, furniture and other surfaces. Of course some energy leaves the building too, but not every falling degree in the living room represents a degree lost to Staffordshire.

This is why the room temperatures often converge overnight. The living room loses its extra advantage; the hall moves less dramatically; eventually the house becomes more even.

That is not just cooling. It is redistribution.

The walls are quietly storing yesterday’s warmth.

The heating does not only warm air. Energy spreads into the building fabric. Plaster, masonry, floors, furniture, cupboards, books, sofas — all of it acquires heat.

Those materials warm more slowly than air, but they also cool more slowly. They act like a thermal flywheel. Once the house is properly warm, the contents themselves help stabilise the room temperature.

This is why a well-warmed house feels different from a cold house with a powerful heater blasting into it. You can get the same air temperature in both situations, but the second room often feels harsher because the walls and surfaces are still cold.

The NIX data suggests the building is doing a respectable job of carrying stored warmth through the quieter parts of the day and night.

The humidity result might actually be the best result of all.

Warmth alone does not guarantee comfort. A house can be warm and clammy or warm and painfully dry. Yours is doing neither most of the time.

A typical indoor humidity of around 51% is very sensible. It is comfortably away from both extremes and, importantly, the hall and living room behave very similarly despite their temperature differences.

That suggests the moisture in the air is mixing around the house more evenly than heat does.

When the heating backs off, does the house fall apart?

No. And that is important.

Across the more useful colder nights, the hall commonly loses roughly two degrees over around nine hours. That is not exceptional super-insulated-house performance, but neither is it bad.

The important word is gradual. A thermally poor house can feel as though someone opened a trapdoor under the temperature as soon as the boiler stopped. Here, the decline is much calmer.

The house remains significantly warmer than outside for hours, and the stored warmth in the fabric helps slow the fall.

So the answer to “does my house keep me warm?” is not merely yes because the boiler works. It is yes because the building itself appears to help carry that warmth between heating cycles.

Comfort is proven. Efficiency needs one more piece of evidence.

The sensors tell us what temperature the house achieves. They do not tell us precisely how much oil or electrical energy was needed to achieve it.

That is the missing piece separating thermal comfort from energy efficiency.

If we add actual boiler runtime, oil consumption and smart-plug power data for the living-room heater, this experiment becomes considerably more powerful. Then we can begin working towards the building’s true heat-loss coefficient — measured in watts per degree of indoor/outdoor temperature difference.

The first 0°C night will be the real examination.

The current dataset has seen outside temperatures down to around 6.4°C. That is useful autumn evidence, but winter will put the building under much more pressure.

At 20°C indoors and 0°C outdoors, the house has to hold a 20-degree difference. At -5°C outside, it is trying to maintain 25 degrees.

That is when insulation, draughts, cold bridges and boiler recovery will become much easier to distinguish.

If the hall remains as calm and overnight cooling remains controlled, the current 7.5/10 score may deserve an upgrade. If not, winter will expose exactly where the weaknesses are.

So, after all that spying, how good is the house?

The house is not pretending to be Passivhaus. It does not need to. It is a real, occupied home with a real heating system and a real owner who likes the living room comfortably warm.

And within that real-world context, the performance is encouraging. The hall is stable. The living room is warm. Humidity is excellent. Overnight cooling is controlled. The outdoor weather is clearly influencing the building, but it is not dictating the indoor climate minute by minute.

THE WEATHER MOVES AROUND.
THE HOUSE MOSTLY REFUSES TO JOIN IN.

If you remember nothing else, remember this.

🚪 The hall tells me how the house itself is doing.

🛋️ The living room tells me how comfortable I am.

🔥 The morning rise reveals the central-heating recovery.

↔️ Heat does not simply disappear — some of it moves around and gets stored.

🌙 At night the house cools steadily rather than dramatically.

And that is the real result of the experiment: the house is not merely somewhere heating happens. The house itself is part of the heating system.

Heating-on times are inferred from temperature behaviour and are not direct boiler telemetry.