Heat loss through “air changes” - air flowing out of a house through draughts, vents and holes - is huge. An old and unimproved house might have 4 air changes every hour. For a typical 3 bed house on a cold 0 degree C day, that means 6 - 8kW being lost through leakage alone. Use this interactive calculator to estimate how much heat is being lost in your house.

Heat loss through “air changes” - air flowing out of a house through draughts, vents and holes - is huge. An old and unimproved house might have 4 air changes every hour. For a typical 3 bed house on a cold 0 degree C day, that means 6 - 8kW being lost through leakage alone. The actual energy cost is incredibly variable, so I wrote an interactive tool to calculate it.

Every time I walk through my neighbourhood on a cold winters day in London I’m reminded again and again how far we have to go to net zero. Row upon row of solid brick terraced houses, endless 1930s semis, even blocks of 1990s flats - all with very high energy needs. Each with the steam from a combi boiler billowing from the rear. And this is in a relatively affluent area - the owners of these houses could almost certainly afford to do energy efficiency retrofits.

Can tap water be used to heat homes? It’s not as crazy as it first seems - the energy released when water is frozen can be extracted by a heat pump and used to keep homes warm. This could be a very efficient source of heat for apartments and houses in the city. The UK faces a huge challenge. 22 million houses are heated with gas - accounting for 77% of heating CO2 emissions.

Winter and Covid combined mean we’re spending a lot of time at home. That means generating moisture. Moisture brings higher humidity, condensation and eventually mold. To understand the most energy efficient way of fixing this, I calculated the energy required for venting and dehumidifying. This revealed something surprising - running a dehumidifier can actually save money. The heat released by condensing the water in the air means it produces more heat than the electricity it uses.

A carbon tax is the best way to stimulate green technology. Unfortunately it’s unlikely to be popular as it is necessarily regressive - it will impact the poorest hardest. In the current political climate no politician will touch it. To win votes, energy prices need to go down, not up. But what if, instead of just collecting that tax, we redistribute it evenly. If the increased price of fuel is offset by a monthly dividend to every household, suddenly our regressive elitist tax becomes a popularist one.

Biochar is created by the pyrolysis of wood and other biological material. Heating the biological material to very high temperatures in the absence of oxygen causes the substances within them to break down into gases, leaving just carbon. This is how charcoal is created from wood. It’s interesting from a climate change point of view as it converts wood - a natural accumulation of atmospheric carbon - into a solid, stable form of carbon which can be buried or stored.

I’m British, and like many British people I live in an old house. In my case, a brick one built in 1949. It may be 71 years old, but for a British house that’s fairly young. In fact, 80% of our housing stock was built more than 60 years ago. Old houses are cold, draughty and poorly insulated. For every house built to modern standards there’s hundreds more that aren’t. This isn’t just a British problem.

The only feasible solution to climate change is technology. We just won’t change our lifestyles based on the abstract threat of climate change. But the technology isn’t there yet. We don’t have all the pieces we need to live the green version of our current lifestyle. Our lives are driven by energy. It makes our cars move and our planes fly, it creates our fertiliser and harvests our crops. It keeps us warm in winter and cool in summer.