Watt a Save - Energy efficient new homes

The energy efficiency of new build homes

The home building industry is adapting at pace to support the country’s net zero targets and deliver increasing energy and thermal efficient homes.

In 2022, The Home Builders Federation released its first 'Watt a Save' report comparing the energy performance of new build homes with older properties. The report found that the home building industry collectively reduced household carbon emissions by 500,000 tonnes and help to save households up to £2,200 in annual energy costs.

HBF continues to examine the potential cost savings and energy efficiency of new build homes in line with quarterly government EPC data and changes to national energy costs.

The latest energy efficiency figures

Last updated: January 2024

Calculations are based on the Ofgem price cap from January 2024, using data from EPC registrations of new and existing properties in the year to 30 December 2023.

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New build homes emit 61% less carbon a year

The average new build home emits 1.39 tonnes of carbon per year, just 39% of that of the average older property, which emits an average of 3.53 tonnes per year.

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85% of new builds have an A or B EPC rating

New build homes are increasingly more energy efficient. Less than 5% of existing older properties achieve an A or B Energy Performance Certificate rating (EPC).

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Making energy bills 55% cheaper

The average new build home is powered by 55% less energy, cutting energy bills by up to £184 a month. That's an annual saving of more than £2,200.

Energy usage per property type

Average reduction in energy usage

New build homes use 57% less energy than older counterparts, cutting the average energy bill by £137 a month. The average new build house uses 66% less energy than older houses.

Under the new Part L regulations, new build homes built from June 2023 will use just 31% of the amount of energy that the average existing property uses.

Calculations are based on Government's EPC registrations data of new and existing properties in the year to 30 December 2023.

Annual energy use (KwH/PA)
Existing New build Part L
 All properties  20547
9156   6409
 Houses 24195 8869 6209
 Flats 13535 8199 5684
17443 7643 5350
 Bungalows 20153 9895 6927

Average annual energy use (KwH/PA)

Average energy use per m2

Critics of new build homes often suggest new properties are more energy efficient as they are smaller. EPC data evidences that this isn't the case, with new build homes using significantly less energy per m2.

Annual energy use per m2 (KwH/PA)
Existing New build % Saving
 All properties  241.6
102.8; 57%
 Houses 239.3 81.1 66%
Flats 240.5 132.5 45%
235.2 103.3 56%
 Bungalows 272.4 104.6 62%

Average carbon savings

New build homes emit 61% less carbon than older counterparts, cutting annual emissions by 2.16 tonnes per property.

The average new build house emits 65% less carbon than older houses. Buyers of new build homes in 2023 reduced carbon emissions by 500,000 tonnes.

New homes built from June 2023 under Part L will emit 73% less carbon than older homes, a saving of over 2.5 tonnes per property each year.

Energy bill savings by property type

Average monthly energy bill savings

The average new build home buyer saves £137 a month on energy bills, amounting to £1,640 a year, compared with purchasers of equivalent older properties. This saving rises to £184 per month for purchasers of houses, rather than flats or bungalows, totalling £2,200 a year.

Properties built from June 2023 onwards - to Part L regulations - will see an average saving of over £2,000, rising to £2,600 for houses specifically.

Prices are based on Ofgem’s price cap for January 2024, using Government's EPC registrations data of new and existing properties in the year to 30 December 2023.

Energy bill savings
Existing New build Annual saving Monthly saving % saving Part L Part L annual saving Part L % saving
 All properties  £2,958.70
£1,318.45  £1,640.31 £136.69  55%  £922.92  £2,035.85  69% 
 Houses  £3,484.02  £1,277.18 £2,206.84 £183.90 63% £894.03  £2,589.99  74% 
Flats £1,949.08 £1,169.19 £779.89 £64.99 40% £894.03 £2,589.99 74%
£2,511.76 £1,100.62 £1,411.14 £117.60 56% £770.43 £1,741.33 69%
 Bungalows £2,902.09
£1,424.95 £1,477.14 £123.10 51% £997.46 £1,904.63 66%

Average annual energy costs (£)

Watt a Save reports

HBF issued Watt a Save reports from October 2022 to July 2023. Now, we maintain and update figures in line with statistical data releases. These updates are available in real time, on this page.

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