Tracking energy signatures of British homes from 2020 to 2025

Clare Hanmer; Jessica Few; Frances Hollick; Simon Elam; Tadj Oreszczyn

doi:10.5334/bc.670

Figures & Tables

Example of the power temperature gradient (PTG) model fitted to (synthetic) data for one house in the UK.

Table 1:

Power temperature gradient (PTG) model options.

MODEL VARIANT	PARAMETERS OPTIMISED	EQUATION
PTG_variable_T_b	HPLC (gradient) T_b (balance temperature) P_b (baseload power)	$P_{tot} = HPLC (T_{b} - T_{ext}) + P_{b} for T_{ext} < T_{b}$
PTG_Solar	HPLC (gradient) T_b (balance temperature) P_b (baseload power) g (solar aperture)	$P_{tot} = HPLC (T_{b (sol)} - T_{ext}) + P_{b} - gI for T_{ext} < T_{b}$
PTG_fixed_T_b	HPLC (gradient) P_b (baseload power)	$P_{tot} = HPLC (15.5 - T_{ext}) + P_{b} for T_{ext} < T_{b}$

[i] Note: HPLC = heating power loss coefficient.

Table 2:

Limits on parameters.

PARAMETER	LOWER LIMIT	UPPER LIMIT
T_b (°C)	5	25
HPLC (W/K)	0	1,000
P_b (W)	0	30,000
g (m²)	0	20

[i] Note: HPLC = heating power loss coefficient.

Example of a poor fit for an individual home.
*Note:* Random ‘jitter’ is added to preserve anonymity.

Table 3:

Statistics for PTG_variable_T_b model parameters for pre- and post-filter runs, 2023–24.

	MEDIAN HPLC (W/K)	STANDARD DEVIATION HPLC (W/K)	MEDIAN T_b (°C)	STANDARD DEVIATION T_b (°C)	MEDIAN P_b (W)	STANDARD DEVIATION P_b (W)	MEAN R²	STANDARD DEVIATION R²
Pre-filter	202	122	14.6	2.24	477	474	0.64	0.18
Post-filter	198	119	15.2	2.31	468	479	0.70	0.15

[i] Note: Results are for 6,935 homes with both runs; and for total energy.

Comparing the T_b results for pre- and post-filter runs, 2023–24.
*Note:* Medians are marked with vertical lines. The results for the total energy for 6935 homes; frequencies < 10 are suppressed.

Heating power loss coefficient (HPLC) results for post-filter runs, 2023–24.
*Note:* The median is marked with a vertical line. The results for the total energy for 6935 homes; frequencies < 10 are suppressed.

Example of the PTG_variable_T_b model fitted to points for a single home, including and excluding days where the home was unoccupied.
*Note:* Power was normalised by maximum daily demand. Random ‘jitter’ is added to preserve anonymity.

Table 4:

Statistics for power temperature gradient (PTG) model parameters for gas only and total energy for a post-filter run, 2023–24.

	MEDIAN HPLC (W/K)	STANDARD DEVIATION HPLC (W/K)	MEDIAN T_b (°C)	STANDARD DEVIATION T_b (°C)	MEDIAN P_b (W)	STANDARD DEVIATION P_b (W)	MEAN R²	STANDARD DEVIATION R²
Gas	197	111	15.3	2.19	219	367	0.72	0.14
Total	205	116	15.4	2.24	485	487	0.71	0.14

[i] Note: HPLC = heating power loss coefficient.

Table 5:

2023–24 statistics for model parameters with the PTG_fixed_T_b model for 6,835 homes, T_b model = total; post-filter.

	MEDIAN HPLC (W/K)	STANDARD DEVIATION HPLC (W/K)	MEDIAN T_b (°C)	STANDARD DEVIATION T_b (°C)	MEDIAN P_b (W)	STANDARD DEVIATION P_b (W)	MEAN R²	STANDARD DEVIATION R²
Fixed T_b	198	119	15.5^a	0.00^a	476	452	0.69	0.15
Variable T_b	189	119	15.4	2.32	468	479	0.70	0.15

[i] Note: HPLC = heating power loss coefficient.

Table 6:

2023–24 statistics for model parameters for PTG_Solar model total: post-filter for 6,935 homes.

	MEDIAN HPLC (W/K)	STANDARD DEVIATION HPLC (W/K)	MEDIAN T_b (°C)	STANDARD DEVIATION T_b (°C)	MEDIAN P_b (W)	STANDARD DEVIATION P_b (W)	MEAN R²	STANDARD DEVIATION R²
PTG	198	119	15.2	2.31	468	479	0.70	0.12
Solar	174	103	18.2	3.44	485	482	0.74	0.11

[i] Note: HPLC = heating power loss coefficient; PTG = power temperature gradient.

Table 7:

2023–24 statistics for daily, weekly and monthly aggregated data, PTG_variable_T_b: total: post-filter for 6,212 homes.

SAMPLING PERIOD	MEDIAN HPLC (W/K)	STANDARD DEVIATION HPLC (W/K)	MEDIAN T_b (°C)	STANDARD DEVIATION T_b (°C)	MEDIAN P_b (W)	STANDARD DEVIATION P_b (W)	MEAN R²	STANDARD DEVIATION R²
Daily	197	117	15.5	1.94	454	348	0.71	0.13
Weekly	227	133	14.3	2.08	471	356	0.80	0.15
Monthly	295	176	12.8	2.29	537	391	0.86	0.06

[i] Note: HPLC = heating power loss coefficient.

Distribution of T_b for daily, weekly and monthly data for 6130 homes, 2023–24, PTG_variable_T_b: total: post-filter.
*Note:* Medians are marked with vertical lines. Frequencies < 10 are suppressed.

Distribution of the heating power loss coefficient (HPLC) for daily, weekly and monthly data for 6130 homes, 2023–24, PTG_variable_T_b: total: post-filter.
*Note:* Medians are marked with vertical lines. Frequencies < 10 are suppressed.

Example of the results for models for different time periods for a single home, PTG_variable_T_b: total: post-filter.
*Note:* Random ‘jitter’ is added to preserve anonymity.

Table 8

Statistics for model parameters grouped by building characteristics, 2023–24, PTG_variable_T_b: total: post-filter.

BUILT FORM	N	MEDIAN HPLC (W/K)	MEDIAN T_b (°C)	MEDIAN P_b (W)	MEAN R²
Detached	1,877	262	15.5	572	0.73
Semi-detached	2,281	201	15.3	483	0.71
Terrace	1,834	177	15.3	446	0.69
Flat	725	90	15.6	297	0.60

[i] Note: HPLC = heating power loss coefficient.

2023–24 median normalised heating power-loss coefficient (HPLC), grouped by house type and house ages, PTG_variable_T_b: total: post-filter.
*Note: n* for each category shown on chart.

Average UK energy price cap, 2020–25.
*Source:* Ofgem (2026).

Mean parameters over time (total energy post-filter).
*Note:* Error bars are ± standard error of the mean, n = 3899.

Change in mean normalised heating power loss coefficient (HPLC) over time by income level.

Tracking energy signatures of British homes from 2020 to 2025

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Paradigm

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