"Bad news is still good information"

After a Dezeen story on research that raised questions about the energy savings delivered by insulation retrofits attracted more than 700,000 views, Insulate Britain campaigner James Thomas discusses how to interpret the findings.

On 20 January, Dezeen reported on an academic paper by Cambridge University researchers looking at the long-term effects of energy-efficiency retrofits in the UK. At first glance, the Dezeen story and/or the paper might seem "anti-retrofit". I want to bring a counterpoint to that knee-jerk reaction.

Bad news is still good information. Information in the form of empirical primary research by qualified professionals with track records in the relevant field, backed up by well-established research institutions, peer-reviewed and published in a respected academic journal – with all parties having a strong incentive not to get caught out doing bad work – is better than most.

At first glance, the Dezeen story and/or the paper might seem "anti-retrofit"

So when such a source presents information that, at first glance, seems to be at odds with what we want to hear, or what we were expecting to hear, we should take a calm moment and listen anyway; we might learn something.

The study is one of the first to use a large dataset (55,154 homes) looking at the impact of real-world retrofits in the long term. The clickbait conclusion is: empirical data shows that energy savings from retrofitting disappear after about four years.

Although the data is new, this finding is not unexpected. Economic theory predicts a "rebound effect" in energy usage following retrofits. A retrofit amounts to a reduction in the (financial) cost of warming your home – so you might well find yourself keeping your home warmer after your retrofit than before it.

Another not-unexpected finding from the paper is that retrofits have a significantly lower impact on energy consumption in homes in deprived areas, which are suffering from fuel poverty. We can assume that households in this category, pre-retrofit, were already spending up to the limit of what they could afford on heating, and that this was insufficient to keep their homes at a comfortable temperature.

After a retrofit, the same level of expenditure on energy would be enough to make such a home comfortable. So the energy usage would stay about the same – but the lives of the people living in that home would be vastly improved.

Two other significant factors contributing to the worse-than-predicted performance of retrofits, not discussed at length in the Cambridge paper, are the variance between buildings and quality control issues in retrofit installation and design.

Poor design or slapdash installation can entirely negate the performance benefits of an expensive retrofit

Different types of houses require different retrofit solutions, as might different houses of the same type. Poor design or slapdash installation can entirely negate the performance benefits of an expensive retrofit. Both of these factors point at the same thing: the need for consistent and reliably high quality in the design of retrofits and their installation.

But what stood out for me most from the Cambridge study, and from everything else I know about retrofitting, is the need for something much better than a retrofit-and-forget programme. A whole-house retrofit transforms your home from a passive pile of bricks and timber into something more like a machine, integrating multiple interacting passive and active systems.

You need to know not to throw open your windows when you're surprised by how warm it is. Your retrofitted house is a machine; you need to learn how to drive it. You might even need to take a driving test.

The study authors say it their way: "Our results call for the urgent need to fully incorporate human behaviour into ex-ante modelling of energy use and to complement financial and regulatory energy efficiency policy instruments with soft instruments to promote the behavioural changes needed to realise the full saving potential of the adoption of energy efficiency improvements."

In short, the rebound effect, and other effects identified by the Cambridge study, can be compensated for if the retrofits are delivered via the vehicle of an intelligent, progressive, integrated national policy. Such a programme would include comprehensive training for engineers, installers and end users, monitoring of both installation quality and post-installation usage, and refresher training where necessary.

Another possible tool, dare I mention it, could be rewards and/or penalties to incentivise sensible use by residents post-retrofit. Controversial, but it exists in many other areas of life where one person's behaviour could have a negative impact on others. Nobody freaks out about the fact we have driving tests and driving licences – as well as fines for bad driving.

Nobody, least of all Insulate Britain, ever said national-scale retrofitting would be easy or cheap

That's why Insulate Britain calls for something akin to the NHS for retrofitting: a National Insulation Service. Such an institution could provide other crucial benefits like trust and a service ethos, consistency across geography and time, data-sharing on what works and what doesn't.

To free-market diehards that baulk at the notion of the less-than-optimal commercial efficiency that could come with delivering retrofits via a large state service effort, consider how we don't marketise core state services like healthcare, education, defence. Aren't providing energy security, eliminating fuel poverty and avoiding climate death also core?

Thanks to the Cambridge study, we now know for certain that a retrofit-and-forget approach won't make the energy savings from retrofits stick. The Royal Institute of British Architects, and the Construction Leadership Council, and the Architects Climate Action Network have all called for a comprehensive national retrofit strategy. The report academics say it their way, Insulate Britain say it our way.

Nobody, least of all Insulate Britain, ever said national-scale retrofitting would be easy or cheap. But it's still easier and cheaper than any other carbon mitigation intervention – if it is delivered in the form of an intelligent, progressive, integrated national policy to include not just money, but also action to support trust, quality control and behaviour change.

James Thomas is a British architect, environmental economist and campaigner. He led the team that designed Extinction Rebellion's pink boat Berta Cáceres and spent two months in jail for blocking the M25 motorway outside London as part of an Insulate Britain protest calling for a national retrofit scheme.

The image was generated using Dall-E 2.

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