Five solutions that reduce a bill once running. They are ordered as they pay back: the cheapest first, and none of them needs anything special about your house.
Draught-proofing an existing house: Sealing the gaps that let air into an existing house: around windows and doors, along the foot of the walls, around pipes and cables, at the loft hatch and in u — Why this one: The cheapest heat you will ever save is the heat that was leaking out. Do this before insulating, not after.
Secondary glazing (retrofit inner pane): Traps a still-air layer against an existing window instead of replacing the window. The considered version is a second pane held in a frame inside the reveal, i — Why this one: Keeps the heat you already paid for, without replacing a single window. The bubble-wrap version costs almost nothing.
Rocket mass heater: A wood heater with an insulated burning chamber that makes a very hot, clean fire, and a long bench of earth or stone that the hot gases run through before leav — Why this one: Burns a fraction of the wood an open fire does, and stores the heat in mass so it keeps giving after the fire is out.
Micro-gasifier (TLUD) cookstove: A small cooking stove, lit from the top, where the wood first gives off gas and that gas then burns cleanly in a second flame above. It gets two to four times m — Why this one: Takes cooking off the gas bill entirely, on fuel you can gather. It also leaves charcoal behind rather than ash.
Line or rack drying for clothes: Drying washing on a line, a rotary airer or an indoor rack instead of in a tumble dryer. The air and sun do the drying for free, removing one of the biggest ele — Why this one: Removes one of the largest electrical loads in the house outright, instead of making it more efficient.
This is a short list, not the whole catalogue
All the solutions for your home are in the catalogue, organized by need.