With support from Random Forest, Castellum has established a modern data architecture that makes it possible to connect everything from sensor data in properties to financial information and customer relations. The result is a scalable, business-oriented platform that strengthens decision-making and creates new value in one of Sweden's largest real estate groups.
The challenge
Castellum is one of the largest commercial real estate companies in the Nordics, with more than 700 properties and 5 million square meters of lettable area. The company operates in four countries, has around 500 employees and a property value of approximately SEK 159 billion. Its operations span offices, logistics and public properties – and therefore also enormous volumes of data.
"We have both classic business data and lots of technical data from our buildings. Just one of our properties can have up to 25,000 sensors that together generate tens of gigabytes every month," says Fredrik Gunnarsson, Data & Insight Lead at Castellum.
In addition to sensor data, Castellum also manages BIM data – digital building models that contain all information about the construction and content of the properties. The challenge was that all this information was scattered in different systems and registers, which created silos and made it difficult to get an overall picture.
“The real estate industry consists of many disciplines – finance, technology, commercial management, construction, and operations – and everyone works in their own systems. This means that the same building can have different names depending on which system you look at. It becomes both inefficient and costly,” Gunnarsson continues.
Data quality was another issue. There were duplicates, missing information and inconsistent IDs for things like elevators, components and customers. As a result, valuable time was spent searching for, correcting and consolidating data instead of analyzing and acting on it.
The solution
To take control of its data, Castellum launched a group-wide data strategy, in close collaboration with Random Forest. The work lasted over a year and involved representatives from IT, finance and operations. The aim was to build a common foundation for how data should be collected, stored, managed and used.
"We formulated an elementary but powerful principle: with easy access to reliable information, we can make wise, fact-based decisions," says Gunnarsson.
The strategy resulted in a new data architecture built on Microsoft Fabric, where data is divided into three layers: bronze, silver and gold. The bronze layer manages raw data, the silver layer harmonized data, and the gold layer handles data products and reports used directly by the business.
Random Forest assisted with solution architecture, data modeling and implementation, but also with methods for working close to the business and creating long-term structure.
An important success factor was that the ownership of data products was moved out into the business. Each data product has a client, data product owner and information owner, making it clear who is responsible for quality, use and further development.
"We wanted the business to own its data – not IT. This creates commitment and ensures that we build things that are actually used. Also, when someone pays for a data product, they become more selective about what they ask for," Gunnarsson explains.
To keep the structure simple and traceable, Castellum has introduced naming standards and governance directly into users' environments. New workspaces in Fabric always follow the same naming and structure, making it easy to find the right data and understand responsibilities.
Another key principle has been that ownership of the platform should remain with Castellum itself. External consultants are used for advice and capacity, but all basic competence and understanding is in-house.
Business benefits
With the new platform, Castellum has taken a big step towards data-driven management. Today, around fifteen data sources and ten data products are in operation, including solutions for energy optimization, supplier management and operational monitoring.
The new structure allows data to be reused in multiple ways – not only in dashboards, but also in applications and portals that consolidate information from many systems and present it through a unified interface.
"Not everything needs to be a report. For example, we are building an operations portal that brings together data from multiple sources and shows the status of our properties in real time. This gives technicians and managers a quick overview without having to log into ten different systems," says Gunnarsson.
The financial benefits are also significant. Just by reducing the time employees spend searching for and compiling information, Castellum estimates that it can save over SEK 50 million per year. In addition, there are efficiency gains in energy, maintenance and supplier management, as well as new revenue opportunities through faster, more informed decisions.
But equally important is the change in approach and culture.
"We've gone from seeing data as an IT project to viewing it as a core issue for the entire business. Random Forest has helped us build the right structure while also challenging us to think long-term. It is only when technology and business meet that the real value arises," Gunnarsson concludes.
Listen to Fredrik Gunnarson talk about the collaboration at the Data Day 2025:
