In the discussion between fabric first and fabric fifth it can often feel as though people are trying to get to the ‘right answer’ rather than looking at where the inefficiencies are, how big they are and trying to decide which is more feasible.
In choosing fabric fifth it means that there will be a need to generate more energy and increase grid resilience. All of this costs and means building more national infrastructure. It’s not the more efficient approach in lots of ways, as it means putting more energy generation in than might be optimally required. Asking people to decarbonise their heat supply is a much simpler message and one which can have the biggest impact on their individual carbon footprint. There can still be a place for other measures too, particularly if people want to fund them themselves, but if it’s hard to persuade people to take up any environmental measures, focusing on the most impactful could bring efficiencies that way. In addition to generating carbon savings more quickly, it could also help to reduce costs in trying to recruit people by using a simpler message, and cutting the costs of assessing homes as the standalone heat pump installation can be simpler than internal or external wall insulation.
With fabric first, there should be less energy needing to be generated. In practice this isn’t straightforward, with lots of evidence suggesting there’s a performance gap arising from quality issues in the install process and then a rebound effect, with many households taking improved energy efficiency as comfort savings. This can lead to an increase in energy consumption – and for those households who are under-heating their homes, with the knock-on impacts on the health of the people and the building itself affected, this can be a good thing on wellbeing grounds.
To get to those carbon savings also means trying to persuade people to take up the deeper levels of insulation it requires. This can be more invasive, with most of the ‘easy’ to treat measures done – such as loft or cavity wall insulation. There are still some remaining but these are more likely to be complicated works such as non-standard cavity walls, or perhaps they are lofts where the amount of things being stored makes it too difficult for the occupants to contemplate the work. The longer it takes to persuade people, the more carbon gets emitted along the way.
I’ve long been fascinated by the idea of the shape of the decarbonisation curve, what that means in terms of the quantum of carbon which gets emitted and crucially what that means in terms of how the shift feels to live through. Reaching net zero by any date by plateauing in a steady state way and then plummeting to zero, or a more gradual downward trajectory both get to the same point. Imagining the shape of those two separate trajectories, and therefore the space underneath them as a proxy for the carbon emissions, shows the amount of carbon generated is much bigger in the first scenario than the second. The first scenario increases the likelihood of feedback loops, which mean the impacts could be more significant. Thinking about the transitions and how they would feel to live through, goes to some quite different places. Even during the Covid-19 pandemic, what felt like a total transformation in how we lived globally led to a c.4-5% drop in carbon emissions in 2020. It’s hard to imagine a precipitous drop which is good for humanity. Whereas the more gradual drop suggests a more managed approach which seems likely to be much easier to live through.
If we lived in a world where everything was aligned to the fabric first approach – funding, regulation, owner and occupants willingness and interest and the supply chain capacity and capability – it could still be the best option. Effective and efficient. If that isn’t where we are, which it isn’t, then the question becomes one of trade-offs. To make decisions means choosing the trade-offs rather than acting as though they aren’t there and continuing to push specific approaches.
We need new stories... 