Nancy Birtwhistle is not your stereotypical eco-warrior.

The 69-year-old grandmother became the oldest winner of the Great British Bake Off in 2014, and now has more than 546k followers on Instagram clamouring for her recipes – and also her innovative tips on how to run the home with minimum impact on the environment.

Motivated to protect the planet to help safeguard her 10 grandchildren’s futures, she’s just written The Green Budget Guide, which features a host of cheap and time-saving tips and tricks on how to run a budget home while protecting the environment at the same time.

“Like many people, I’m feeling challenged by the increasing cost of living,” she observes. “By combining a budget-friendly lifestyle with an eco-friendly one, we can begin to hit the difficult times with gusto, rising to face the financial challenges and actually feeling quite proud, empowered, resilient and resourceful too.

“Why spend money on something when an easy switch or saving can be made that will free up funds to use on other things? Better use of the earth’s valuable finite resources should be on the agenda for all.”

Here, Birtwhistle shares some of her eco-friendly household tips…

1.  Cut energy costs on electrical appliances

Simple changes can help mitigate the rising cost of energy, says Birtwhistle, including turning down thermostats, not heating empty rooms, and boiling only the water you need when filling the kettle.

“Spend a few minutes getting to know your appliances so you can become smart and savvy, understanding which ones are the energy-guzzlers,” she advises. “I’m beginning to enjoy prudence with energy use, as I realise so much can be achieved from just one power source.”

For example, she suggests making maximum use of the oven when it’s on by batch cooking, and then freezing meals to reheat later in the microwave.

“When it comes to the electricity consumed by various appliances, a good rule of thumb is anything that’s switched on to generate heat, such as ovens, tumble dryers, electric radiators and kettles will consume more electricity than those appliances that don’t,” she warns.

2.  Tackle mould on walls without nasty chemicals

Although it saves money to turn the heating down and heat only the rooms in use during the winter, Birtwhistle points out that the downside is that any damp areas can soon become “a playground for mould”, which is a health hazard as well as being unsightly.

After first checking the reason for any mould, she suggests then simply dipping a warm, slightly dampened cloth into two tablespoons of dry bicarbonate of soda and rubbing over the mould, being careful not to over-wet the area or damage the wall if it’s wallpapered.

“Bicarbonate of soda has a pH of around 8 to 8.1, which is too high for mould to thrive,” she explains. “Bicarb also cleans and deodorises, so it provides a three-in-one natural cleaning solution for mould on walls.”

3.   Make cooking oil go further

Cooking oil can be re-used, advises Birtwhistle. Simply use a funnel to pour the completely cooled, used oil into a bottle with a lid, using a tea strainer over the funnel, which can also be lined with kitchen paper or a paper coffee filter.

“The strained oil will be crystal-clear and can be used at least three or four times more,” she explains. “If in doubt about how many times to use your oil, if it discolours or has an unpleasant smell, don’t use it again.”

4.  Be clever with your freezer

Using your freezer well can help save money if you buy in bulk, batch cook and freeze meals, and also helps avoid food waste. “For the budget-conscious, eco-friendly, no-food-waste-minded of us, the modern household freezer is an absolute gem,” declares Birtwhistle.

Her clever freezer tips include washing and drying one large root of fresh ginger, breaking it into a few pieces, and freezing them in a bag. “When a recipe calls for fresh ginger, simply grate it from frozen, then pop the rest back into the freezer,” suggests Birtwhistle, who says one large root of fresh ginger can last her around six months.

“The same applies for fresh chillies, lemongrass, and peeled garlic cloves, all of which are easy to chop, slice or grate straight from the freezer,” she adds.

5.   Make your own eco-laundry detergent

Birtwhistle says she hasn’t bought laundry detergent for years, because it’s so expensive (around £7 for a litre or 18p per wash, she says), and often comes in difficult-to-recycle plastic bottles.

She says: “Biological detergents are harmful to the environment, and the eco-friendly alternatives can cost four times as much as their chemical-heavy equivalents. Try my liquid soap, which does a sterling job in both the washing machine and on hand-washed delicates.”

Birtwhistle’s liquid soap recipe makes five litres for less than £1. You’ll need 150g soap slivers or single-use hotel soaps, 1 litre of just-boiled water, 150g washing soda crystals, 20ml eco-friendly washing-up liquid, up to 2.6 litres cold water, and a few drops of lavender essential oil (or fragrance of choice, optional).

Chop the soap into small pieces, then blitz in a blender to form a fine powder. Transfer to a large saucepan and pour over the just-boiled water. Stir until dissolved. Add the washing soda crystals and stir through – if it clumps, use a hand blender or potato masher.

Once completely smooth, add the washing-up liquid and 1 litre of the cold water and stir well. The detergent will thicken as it cools, so add a further litre of cold water, stir well, then leave to go completely cold.

Once cold, if the detergent remains thick and gloopy, add the remaining 600ml cold water with a few drops of food or soap colour and your essential oil of choice. Then pour the mixture into reused plastic bottles and use 100ml straight in the drum for a long, eco, 20 degree cold wash, or use 80ml for hand-washing of woollens and delicate fabrics.

6.  Make Pure Magic cleaner

Birtwhistle’s Pure Magic cleaner is made from her own simple recipe, and she says: “Pure Magic does exactly what it says – it’s eco-friendly, very little is needed (just a squirt here or there) and it has so many uses. It tackles laundry stains – curry, fruit, tomato, grass, wine – is a natural whitener, dissolves limescale, green algae, kills mould, clears soap scum and is the best toilet cleaner. It really is magic!”

To make it you’ll need a 500ml (17fl oz) heatproof measuring jug, a spray bottle, 200g (7oz) citric acid, 150ml (5fl oz) just-boiled water, 20ml (3/4fl oz) eco-friendly washing-up liquid, and 10 drops essential oil (optional).

Place the citric acid in the jug, pour over the water and stir until completely dissolved – clear with no crystals remaining. Once cool, add the washing-up liquid and, if using, the essential oil for perfume. Leave the liquid in the jug to cool completely, uncovered, for a few hours then transfer to a spray bottle.

She adds: “While Pure Magic is a beast of a cleaner, it’s not suitable for use on surfaces such as tables or worktops, because if it’s not rinsed well it will dry sticky. It’s an acidic cleaner, so it’s not advised for use on natural stone, slate, granite or marble.”

The Green Budget Guide by Nancy Birtwhistle is published by One Boat, priced £14.99. Available now