Housing London: How data is tracking London’s energy

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Climate change is one of the world’s most pressing issues, particularly the need to reduce carbon footprints to bring global heating under greater control. Around 22% of the UK’s carbon emissions come from our homes, according to the Energy Saving Trust, and data can be used to help promote energy efficiency in our properties, reduce carbon emissions and inform government environmental strategies.

To do this, the data needs to be accessible and comprehensive. Steve Evans, senior fellow at the University College London Energy Institute, helped design the London Building Stock Model, which aims to provide energy usage data in an easily digestible form.

The model is designed to show the energy efficiency of every building in London, explains Evans. This can then help authorities understand where improvements are required, and which areas of London struggle the most with energy efficiency and fuel poverty.

“If you don’t know what the current situation is, you have nowhere to start from,” he adds. “In a way, this model is a ‘base case’ for what has got to be improved upon.”

The model was commissioned by the Greater London Authority (GLA) as part of the city’s attempts to become zero carbon by 2050. Designing the model took two years, and it is accessible to the public. A more comprehensive version is available for the GLA and other organisations that require access to it.

It works by showing an interactive map of data on every domestic and non-domestic property in all 33 London boroughs. This includes the age of buildings, as well as their proportions, construction materials, servicing systems, and the nature of activities on each floor of commercial and public buildings.

Each building also has an energy efficiency grading. The model can then show how energy efficiency is improving, stagnating or declining in the city, and where pockets of fuel poverty exist.

Building a 3D model of every building in London was complicated, Evans says. The current approach is based on Ordnance Survey data, information on business rates, Environment Agency data on flood risks and information from the Land Registry.

Energy performance data and display energy certificates, published by central government, are also used to show which buildings have roof insulation, how they are heated, and whether double glazing is in place, among other things. The model shows much of London is mid-terrace, pre-WWII, with a grade D environmental rating and lacking double glazing.

“Once you get to this point, you have a lot of data – that’s not necessarily what some companies would call big data, but it is pretty complex and difficult to manage easily,” says Evans. “But the key thing for us is it all pulls together on a map – it works together spatially. The sum is far greater than the individual parts in what we have created.”

The scale of doing this project for a city of almost nine million people is challenging; one of the big issues, Evans says, is the diversity of London’s buildings, with businesses, flats, Victorian terraces and modern apartments often co-existing in similar places.

“Buildings can be very mixed in their use,” he adds. “Sometimes, in new developments, this is intentional, but for many parts of London this is economic forces at work, as people convert houses into flats or rent above a shop. This makes it difficult for us to categorise a building as a whole.”

There was also the trouble of aggregating the data – showing, for example, the energy rating for an entire block of flats as well as the individual buildings. Additionally, only a third of buildings in London have an energy performance certificate (EPC), so the team had to predict EPC ratings for houses by comparing them with similar buildings.

There has been interest in the model from other world cities, as well as towns and cities in the UK, Evans says. The team is working on a separate solar potential 3D model of London, to help identify where solar panels could be encouraged, and further alterations to the housing stock model could uncover additional data.

“With the climate emergency, there’s a realisation that tools such as this are really needed to focus our efforts,” adds Evans. “Years ago, there wasn’t the data to do this sort of thing, but there is more data sitting in central government that would make the model better. We’re hoping it will engage the public with what needs to be done to improve the energy efficiency of buildings.”

This article was first published in the January 2021 issue of Impact.