On June the 14th 2017 the fire in Grenfell Tower in London destroyed the lives of many. The devastating high-rise fire was started by a faulty fridge-freezer on the fourth floor and spread rapidly up the building's exterior because of the flammable cladding and insulation covering the tower. 72 people did not survive the disaster.  

To make sure a scenario like the Grenfell Tower fire never happens again, the Building (Amendment) Regulations 2018 (SI 2018/1230) came into force in the UK. A residential building taller than 18 meters cannot contain combustible material within the external walls. The height will likely be slashed to 11 meters in the future.

Automatic portfolio scan for heights

A large independent insurance brokerage in the United Kingdom vowed to solve all safety risks as soon as possible. This means they had to check the cladding and insulation on all their estates taller than 11 meters. It’s a big challenge for anyone managing a large real estate portfolio. This is especially the case if the building heights haven't been recorded properly. This would require having every singly building measured before starting with the material check, which is a colossal task!

Sparked by high demand from our UK customers, Spotr has developed a quick portfolio scan through which all building heights are automatically generated. This information gets uploaded into our property intelligence platform for everyday use.

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What were the steps?

In order to develop the capability for measuring heights automatically, Spotr had to come up with a new approach. Spotr's go-to method is to use Streetview images to calculate the measurements of facades and facade elements. However, with high-rise buildings, the facade often isn't entirely visible on a Streetview image, making it hard to see where the roof’s edge is. So, to measure the actual building heights, Spotr decided to work with height maps. Here is how Spotr did it:
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• The Spotr team started by checking the list of addresses. The addresses sometimes differ from how the Spotr system reads them, so a thorough clean-up and a check of the list are necessary before the team can continue.
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• Next, the estate or building is connected to the address by geocoding. Geocoding is the process of converting addresses into geographic coordinates. After this, the team plotted the outline of all buildings on a map.
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• The team then searches for data, for example, a satellite-made map, and put the outline of the building on top like a stamp. Other data the team can “stamp the outline onto” is a height map made with laser data from satellites. The height is gathered from both a Digital Service Model (DSM) and a Digital Terrain Model (DTM). The DSM calculates the total height, and the DTM calculates the height of the surrounding landscape.  
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  Since buildings in the UK are often located on elevated terrains, Spotr subtracts the terrain height from the total height to get the height of the building.
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• Finally, the team marks the middle, where in a grid of 5 by 5 meters around the middle, the highest point is searched. That raises the question: if the 5 by 5 grid has an antenna, does it count as the highest point?  
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  The answer is no, Spotr excludes elements like chimneys and antennas, as they are not a structural part of the complex. If it’s an elevated shaft, Spotr does count it as the highest point. The rule is: it only counts as the highest point if the diameter of the element is big enough.

Over 120,000 buildings measured digitally

Using this new method, Spotr has digitally measured over 120,000 buildings scattered throughout the United Kingdom. The process has also been automated and added to the Spotr platform, meaning every Spotr user now sees the minimum and maximum height of their buildings on the quick view page. The height filter on the map is accessible to all users as well.  

This exercise is one of the many property portfolio inspections that Spotr can provide for its customers.  

Want to know more?

Here at Spotr, we use geospatial imagery to automatically inspect the condition of the property and its associated risks. Spotr is an AI-powered digital inspection platform, helping you to gain insights into your insured portfolio. Helped by computer vision, Spotr is able to analyze a huge, up-to-date image database in which data about your real estate portfolio from different sources are collected. With this enriched database, you can easily analyze your property insurance portfolio.

Want to know more? Request a demo here.