How we heat our homes — as seen from outer space

Home heating with fossil fuels no longer makes sense, and the time is nigh for an all-electric revolution

Sometimes when I’m teaching, I ask my students to imagine an alien who lands her spaceship in the middle of a field in rural Ireland. The aliens starts wandering the country roads, trying to figure the place out.


The countryside is dotted with bungalows, naturally. The alien gets curious and knocks on one of the doors, full of questions for the man who answers.


‘So how do you heat your home?’ the alien eventually asks, and the homeowner says that he heats it with oil. ‘Oh I see,’ the alien says, ‘so where do you get that from then?’


The homeowner isn’t sure, but he thinks it’s probably from somewhere in the Middle East. Our alien friend is a bit flummoxed. ‘Sorry I think I misheard you,’ she asks, ‘did you say that it comes from someplace several thousand miles away?’ The man nods in the affirmative.


‘So how does it get to your house?’ the alien asks, ‘does it come in a pipe?’


‘Oh no’, he says, ‘I think it arrives in a big ship at Dublin Port, and they pump it off the ship into a big tank.’


By now the alien is chuckling quietly to herself and can’t wait to get back to her spaceship to tell this to all her alien mates. But first she wants to hear more.


‘So how does the oil get to your house?’ she asks, and the homeowner says that someone fills up a truck from the big tank at Dublin Port, and then drives the oil up every little lane in the country, delivering it to all the houses.


So the alien says, ‘let me get this right, you ship this stuff across the sea from 5,000 kilometres away — this must be the greenest, cleanest energy source imaginable, to make it worth all that trouble?’


‘Well no,’ the homeowner says sheepishly, ‘as a matter of fact they say that it’s very polluting and that it’s causing dangerous levels of global warming.’


By now the alien is completely beside herself with confusion.


Phasing out fossil fuels

In my work, I like the challenge of trying to get people to see things from a different perspective. Sometimes we need to snap out of our bubble to see just how illogical the energy systems we’ve created are.


Thankfully, though, things are starting to change when it comes to fossil fuels. New oil and gas boilers (including replacement boilers in existing homes) may be banned in Ireland from as soon as 2025. In the UK they will be banned in new build from the same year, and from all properties by 2035, under current plans.


This is going to represent something of a culture shock for two nations that made oil and gas the primary means of heating our homes over the past half a century.


But change is coming regardless. We’re moving rapidly towards the all-electric house. Think about it like this: the best gas or oil boilers on the market have an efficiency of well over 90%, but even the worst performing air-to-water heat pumps typically have an efficiency of at least 250%.


The electric revolution

My family have been on this journey for the last eight years. When I built my passive house in 2005, we put in a wood pellet boiler. But after a while, I started to doubt the logic of burning wood — which is about 50% carbon when dried — rather than locking that carbon up by using the wood to build homes, make insulation, or just leaving it in the forest. We installed our air source heat pump in 2016 and haven’t looked back. We have no pellets to store, no ash to clean, and just one bill.


Recently my wife Mairead needed a new car. We were filling up the petrol tank one day, and we had this moment where we both looked at each other across the forecourt, and I said to her you know, it doesn’t feel right buying another fossil fuel vehicle. And she felt the same.


So we now we have our first electric car. Next, we’re going to put a big 6kW solar PV array on our roof so we can charge the car and power the house with our own clean electricity. I like to think we’re moving from a passive house to a super-charged passive house, and we feel privileged and grateful to be able to do that.


Now our alien visitor might be inclined to ask, well, where’s your electricity coming from? And it’s a fair question. But as we move away from peat and coal, Irish electricity is getting cleaner all the time. Over 40% of electricity in Ireland came from renewables in 2020 — with the vast majority of that generated by wind power — and the government is aiming to increase that to 80% by 2030. The UK, meanwhile, is planning to fully decarbonise its electricity supply by 2035.


Of course there are still challenges. We need most electricity in the winter, which is when our PV panels will produce the least. And storage is still a big issue. But in this part of the world we have an amazing wind resource, not to mention other renewables, and we have a long way to go to maximise them.


Here in Ireland, for the first time in my life, people are now worried about power outages. Energy costs have skyrocketed. Homeowners might feel anxious about the idea of putting in a heat pump given the price of electricity.


Fabric first

This is why, you won’t be surprised to hear me say, we need fabric first homes too. Passive houses use up to 90% less energy for heating and cooling than a typical home, for example. They are much better protected from the volatility of energy supply and price. Think about it like this: my mother’s inefficient home needs a 38kW boiler to heat it, but my passive house only needs a 6kW heat pump. When your home needs so little energy, you can start to see the logic of making it all electric.


The other amazing thing about electricity is that we can make it ourselves. None of us can make oil or gas, but you can put a solar panel on your roof or in your garden and use it to generate cheap, clean energy.


This points the way towards a future where we are all producers of electricity. Look at the new Tinakilly Park development in County Wicklow by D/RES Properties. There, residents can not only generate their own electricity, but buy and sell it with their neighbours on a micro grid. This can help to foster a sense of community, too.


If you had described this concept to people 20 years ago, they would have thought you were mad. But now it’s happening right on our doorstep.


Our alien friend might not be laughing so much the next time she pays us a visit.

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