Powerwall - Tesla home battery (7 or 10 kWh). This quite literally changes everything!! I recently checked our 3 bed home (built in the 1920s) typical energy use per day and it came in at 7.7 kWh per day. So if I charge the tesla home battery when it's windy or cheap or low carbon, I can make my home cheaper and cleaner to run.
Nest Smart Thermostat - Most people do not regularly programme their thermostat, but it influences the vast majority of energy use in your home, heating or, if you're lucky enough to live in a warm climate, cooling. Nest basically gives brains to your home heating system. It adjusts it if you're too hot or cold, turns off if you're away on holidays or business and can even reduce demand on the grid at times of high energy use.
Kingspan insulation - The first three steps in creating a warmer home is insulate, insulate, insulate! Kingspan have been at the forefront of creating warmer homes and buildings for the past 50 years. From humble beginnings they are now the world's largest insulation company and create all types of insulation for new builds and retrofit markets.
There were lots of close runners for our list so please let us know if there are any missing you think should be here