Energy efficiency is often confused with Energy Conservation.
Both will potentially result in reduced energy bills and can reduce greenhouse gas emissions, but they are different and whilst Energy Conservation simply means switching off appliances Energy Efficiency is best defined by "using less energy to provide the same service".
We have provided a couple of examples for you to consider.
When you replace single glazed windows in your home with an energy-efficient double glazed windows the new window prevents heat from escaping in the winter, so you save energy by using your heating system does less to create the same temperature as before. This is Energy Efficiency.
When you replace an appliance, such as a refrigerator or clothes washer, or office equipment, such as a computer or printer, with a more energy-efficient model, the new equipment provides the same service, but uses less energy. This saves you money on your energy bill, and reduces the amount of greenhouse gases going into the atmosphere. Again this is Energy Efficiency.
Whereas simply switching off a light in a room where it is normally on is not Energy Efficiency but Energy Conservation. Energy conservation is reducing or going without a service to save energy.
Both efficiency and conservation can reduce greenhouse gas emissions.
Ideally you should consider both Energy Efficiency and Energy Conservation.
The best source of information and general advise is the Energy Savings Trust. The Energy Savings Trust is a social enterprise with a charitable Foundation. They were formed in 1992 and through various partnerships they offer impartial advice to communities and households on how to reduce carbon emissions, use water more sustainably and save money on energy bills.
They also work with governments, local authorities, third sector organisations and businesses.
The website for the Energy Savings Trust is separated into:
Grants depend on a number of factors from what you want to do, your income and where you stay, the most up to date available is from:
https://energysavingtrust.org.uk/?s=grants+and+loans&post_type[]=grantsandloans
Citizens Advice also provide advice on Energy Efficiency matters and further information can be obtained here.