THERE was no joke about it – the house was an icebox.

Our breath, crystallised into water droplets in the morning, spelled out potential disaster.

Decked out in thermals, woollies, coats and gloves, we’d made a silent but communal resolution to withstand the cold rather than blast the heat.

In the beginning it was an adventure. But by the end of October, when snow fell for the first time in 30 years in central London, we’d had enough.

We flipped the switch. Then the boiler packed up. The timing couldn’t have been worse. Or better. We might have been freezing, but the Energy Saving Trust was also telling people that what we needed to do to stay warm wasn’t to turn up the heat, but insulate the loft, strip insulate our windows and stop using our chimneys, energy-inefficient as they were.

So instead of dare ourselves to not freeze, we decided to try out an eco audit. That’s when eco-auditing guru Donnachadh McCarthy stepped in. Blessed with a thermometer, an energy monitor (which reads how much energy an appliance uses both when on standby and in use) and the encyclopaedic knowledge of a green giant, Donnachadh wandered with us from room to room measuring things like drafts, light usage, how much time we spent in which areas and insulation. What he found in our four-storey Victorian mid-terraced house was quite shocking. Taking in full stock of the house, from cellar to loft, Donnachadh gave us a full list of notes on how we could cut costs.

l Easy Eco Auditing, by Donnachadh McCarthy, published by Octopus, £7.99.

HEATING It has unbelievable charm, but our house is also large, drafty and very badly insulated. While we might be slightly ahead of the rest of Britain by subscribing to a green electricity tariff, 100 per cent of which comes from renewable energy (ecotricity.co.uk), we have been using too much.

Our boiler’s energy efficiency rating was a paltry 79.9 per cent. By replacing the boiler with a newer model we could save around 20 per cent on our gas bills.

The temperature in the house is 19C; one degree warmer would add ten per cent to our gas bill.

Our boiler is set on a timer, with separate controls for the central heating and hot water. By finding out the times we need the hot water and heating we were able to shave off three hours per day from our heating bill, roughly 20 per cent per month on our bill.

RADIATORS Many of the radiators in the house are placed under windows, meaning that up to 70 per cent of the heat is lost straight through the glass above or through the outside wall.

This can be corrected by installing a shelf above the radiator, which will block the heat from escaping up through the window and a reflector panel to reflect the heat into the room.

Reflector panels are available in most large DIY stores or from proeco.co.uk.

FIREPLACES Up to 15 per cent of the central heating in a room can be lost up an unsealed fireplace.

After investing in a chimney balloon, which set me back £19.99 from proeco.co.uk (you can also try the website chimney-balloon.co.uk), the room became five degrees warmer.