Preview: Charts 16 – Retrofit energy before and after, with the works listed

RAVENSBECK RETROFIT · CASE STUDY 14

Same house, under half the energy.

A two-up two-down in a stone terrace, built in 1898. We insulated it inside and out, swapped the boiler for a heat pump and read the meters for a full year either side.

−60%

less energy bought

21,400 kWh a year down to 8,600

£1,070

saved in the first year

At the tariffs we paid in each year

ENERGY BOUGHT IN A YEAR, kWh

Heating went from two thirds of the bill to under half.

BEFORE · 2023

21,400 kWh

14,2003,6002,900700

AFTER · 2025

8,600 kWh

3,9001,3002,700700

Space heating
Hot water
Appliances and lighting
Cooking
No longer bought

What changed between the two bars

Loft: 300 mm mineral wool Up from 50 mm, with boarded storage kept
Walls: 90 mm external insulation Rendered, with new sills and extended eaves
Heating: 7 kW air source heat pump Replaced a 2006 gas combi boiler
Windows: Triple glazed timber Eleven windows and the back door
Airtightness: 8.9 down to 3.1 Air changes an hour at 50 Pa, tested before and after
Total cost: £38,600 Grant After a £7,500 heat pump grant