A Dynamic Platform for UK Housing Stock Decarbonisation

In this blog the authors outline the challenges we face decarbonising the UK housing stock and provide an insight into a new dynamic modelling platform (Energy Hub) that they are developing. 

“How do we decarbonise our Carbon-hungry homes?”

The UK was the first country to enshrine in law its commitment to reduce greenhouse gas emissions, with the effect that the 2008 Climate Change Act commits the UK to reduce CO₂ emissions by 80% with respect to 1990 levels by 2050. More recently, the UK has signed the Paris Climate Change Agreement, which goes further, committing the UK to be net zero-CO₂ by 2050 and the 2008 Climate Change Act was amended in 2019 to reflect this.

A great deal of intellectual energy is now being expended to understand how we can achieve this incredibly ambitious target, without compromising economic growth. But one thing is already clear, the transformation of the UK’s housing stock will play a crucial role. This is because housing is responsible for over a quarter of the UK’s Carbon Dioxide emissions, around 80% of which is due to space heating and hot water use. Put simply, we need to develop strategies to decarbonise the heating of our houses and the hot water we use in them, both of which are almost entirely reliant on fossil-fuel based central heating systems.

Achieving this ambitious aim will require massive structural improvements across the board. It will require improvements to the thermal performance of the housing envelope, through lower wall, floor, roof and glazing U-Values and reduced infiltration heat losses through better draught stripping, or better yet through mechanical ventilation systems with heat recovery. It will also require a shift away from the now almost ubiquitous gas central heating and hot water systems to electrical systems, such as heat pumps.

Through a combination of renovation and new construction our housing stock has already undergone significant improvements since the 1973 oil crises, which paved the way to the first, and increasingly stringent ever since, regulations for the conservation of heat and power. These regulatory improvements were complemented with subsidies to encourage investments in the building envelope and in more efficient gas central heating systems. But interestingly, carbon emissions from housing have increased over the past thirty years. This is partly because there are simply more houses now than there were thirty years ago. But it is also, in fact mainly, because of changes in lifestyle. We heat our houses far more than we used to, so that the average indoor temperature has increased significantly, and we also use far more electrical appliances. These two factors, the so-called “rebound effect”, have more than compensated for the improvements to the thermal performance of our homes.

Furthermore, some recent policy interventions such as the Green Deal have failed to achieve the anticipated uptake of housing decarbonisation investments. Or else, in the case of the Feed-in Tariff, they have been too successful: leading to far more installations of photovoltaic (PV) panels, and associated subsidies, than were anticipated.

So, the situation is complicated. We need to understand how we can reduce energy demand in the first place, mainly through conserving heat, and how we can substitute heating and hot water systems with more energy efficient (electric) alternatives. But this of course, only makes sense if the technologies we use for generating electricity, whether these are centralised or distributed (as with PV panels), are also decarbonised. We also, and this is the most complicated part, need to anticipate lifestyle, and even demographic, changes; and the likely uptake of policy measures that are designed to stimulate the much-needed transformation of our housing stock’s Carbon intensity.

Providing these insights to improve the evidence base for, and ultimately the success of, future housing stock decarbonisation policy measures will require comprehensive models.

The UK has a long and proud history of developing energy models of the its housing stock. Indeed some 29 such models have been developed since the 1973 oil crisis. But these are simplified models that do not support a faithful representation of the lifestyle factors mentioned earlier and the corresponding implications for health and comfort. To address this, a team at Sheffield School of Architecture has developed a new dynamic housing stock energy modelling platform, called the Housing Energy Hub (or “EnHub” for short). This is a modular open-source platform that simulates the dynamic performance of the UK housing stock, through the representation of archetypes, representing the distribution of housing shape, size, tenure, age, systems and location. EnHub does this through the use of standard, regularly updated datasets, so that its simulations can in turn be updated as new datasets are published.

In its present form, EnHub enables us to test the effects on future carbon emissions of scenarios regarding changes to housing fabric and systems and household lifestyle factors. But work is currently underway to augment this largely physical modelling capability with new social models to predict the likely impacts of future policy measures; complementing our representation of housing archetypes with household archetypes and the behaviours of these household members. This will provide a powerful resource to support the government as it ramps up its plans to achieve our zero Carbon future!

This social simulation extension to EnHub also has the potential to anticipate the likelihood that viral diseases like Covid-19 would be transmitted within and between households, and to evaluate measures to mitigate this risk.

Views expressed by authors may not represent the views of CaCHE.

 

Date: November 18, 2020 2:16 pm

Author(s): Gustavo Sousa and Professor Darren Robinson

Categorised in: Wider Drivers