When we moved into our new house on Dublin's southside in the winter of 1973 Ireland had just been hit by an oil price shock. The house had been built for an era of low oil prices: poor insulation and high oil prices meant that our first winter in the house necessitated woolly jumpers.
As a nerdy energy economist, I logged our energy use from the outset, so I can track carbon emissions from our home over the past 40 years, offering some broader lessons.
Our electricity emissions are now a third of what they were in the early 1990s
In the 1980s, our family of two adults and three children emitted almost 12 tonnes of carbon dioxide a year. In the 1990s, this rose to about 16 tonnes, with emissions from heating the main factor. While we had built an extension in the late 1980s, the main reason was probably that more of the house was heated as our teenagers closeted themselves in their bedrooms.
Today, our household emits about eight tonnes a year, half our 1990s peak. However, as an empty nest of two people, our emissions per head have gone up slightly. There are economies of scale – larger households make better use of heated rooms. As average household size in Ireland gradually declines, this is an issue.
In 2009, we undertook a major revamp of the house, which involved replacement of the heating system with a more energy-efficient gas boiler, new pipework, and a major upgrade in attic insulation. This work involved serious disruption to the household for a few weeks.
As a result of these upgrades, our gas usage has fallen by about 40 per cent – in cash terms, a saving of about €9,000 over the past nine years.
As the cost of the energy efficiency improvements was about €10,000, the investment has not yet paid off financially.
However, a significant part of the benefit of a more energy-efficient house is that it is more comfortable, particularly important as we get older. This greater comfort, combined with lower fuel bills, means the investment has already amply repaid its up-front cost.
To make our house fully carbon-neutral we would need to invest a lot more in further measures. At the current carbon price that would not repay the cost, but increased carbon taxes would change the cost/benefit ratio.
Other areas where our family has reduced emissions are electricity and transport. Our electricity emissions are now a third of what they were in the early 1990s. Half of this improvement reflects more efficient appliances. A modern cooker with better insulation has lowered our energy use and led to fewer burned Christmas cakes. Other more efficient appliances, such as the fridge and washing machine, have played a smaller, but a real part.
The other 50 per cent of the emissions reduction reflects greener electricity generation – renewables matter. If Ireland closed peat-fired generation and coal-fired generation tomorrow, at a stroke this would further halve our family’s already reduced emissions from electricity.
There are two main reasons behind a fall of two-thirds in our family’s emissions from transport. The first was the arrival of the Luas, a much more efficient way to commute, which reduced our annual car mileage by half. The second was a shift to a hybrid car, cutting our petrol emissions by a further 50 per cent.
There are a number of lessons for policy from this personal saga. The biggest problem for Irish households is eliminating the fossil fuel energy consumed in heating our homes.
However, major home improvements are not only expensive, they are also inherently disruptive, and this will remain an obstacle to people retrofitting their homes. We need to look for ways to make this as painless as possible for families.
While getting the financial incentives right is essential, finding a way to ease the disruption may be even more important. People will also need to be reassured that those who carry out the work are adequately skilled and reliable.
In the case of transport, electric cars will be a game changer in the next decade. But air travel remains a challenge. For our family, the fact that our grandchildren live in the United States means our emissions from air travel are now very significant.
Technical progress in reducing aircraft emissions is much slower than for cars. That’s unlikely to change unless higher fuel bills see changed incentives for aircraft manufacturers. The prospect of ever-rising fuel prices led car companies to invest in more fuel-efficient technologies.
Likewise, if rising taxes were imposed on aviation fuel, that would lead aircraft manufacturers to invest in more energy-efficient alternatives.