Recycling the past, refreshing the air: Circular transformation of The CUBE
Located in Hellerup hear Copenhagen and owned by pension fund PKA, The CUBE is a well-known office building originally designed by Schmidt Hammer Lassen in 2001. From the outset, the architecture was ideal for natural ventilation, with a strong cross- and stack-effect strategy built into the design. A generous central atrium connects all five levels, acting like a ‘vertical lung’ for the building and allowing warm, stale air to rise and escape at the top. On each floor, highly placed, automatically operable awning windows in the façade support cross ventilation, drawing fresh air across the floor plate and into the shared spaces around the atrium. What began as a single-tenant headquarters has now evolved into a multi-tenant workplace – and the indoor climate system has evolved with it.
Visit a reference projectSolution
Location
Hellerup, Denmark
Sector
Commercial Buildings
Project Type
Refurbishment
From one tenant to many: new demands on the indoor climate
In 2023, Over Byen Architects reimagined The CUBE to support a flexible multi-tenant setup, and HØGHØJ carried out a comprehensive upgrade of the building’s ventilation and indoor climate control. With several different companies now sharing the building, each with its own working patterns, occupancy levels and comfort preferences, the original one-size-fits-all strategy no longer matched the daily use. The ambitions for the renovation were clear: • Optimise energy use by making full use of the existing natural ventilation potential • Improve comfort and air quality for all tenants, with a system that responds dynamically to actual conditions • Give facility management a better overview, with data logging and central control • Support ESG ambitions, including a more circular approach to end-of-life components To achieve this, the project partners needed an intelligent natural ventilation solution that could integrate seamlessly with the existing Building Management System (BMS) and give each zone its own tailored strategy.
Smart ventilation with NV Advance®
WindowMaster contributed to the renovation with a new natural ventilation system based on NV Advance®. The solution communicates with the building’s BMS via KNX field bus, making it a fully integrated part of the overall building control strategy.
NV Advance® uses algorithms and sensor inputs to calculate exactly when the new WindowMaster actuators should open or close the windows – and by how much. This allows the system to:
- React to indoor temperature, CO₂ levels and time of day
- Use outdoor conditions to bring in fresh air while avoiding draughts
- Take advantage of the atrium and façade geometry to drive stack and cross ventilation efficiently
At the same time, status information from the motorised windows – open/closed position, faults and alarms – is sent back to the BMS. This gives the facility manager a complete, real-time overview of the building’s natural ventilation, directly in the systems they already use. WindowMaster also handled system start-up and commissioning, ensuring that the control strategy matched both the architecture and the new usage patterns.
Better comfort, better control – for tenants and facility management
With the upgraded system, The CUBE now has a more detailed zoning and control strategy that reflects its multi-tenant reality: • Comfort tailored to usage – each floor or zone can be controlled according to how it is used, whether as open-plan offices, meeting spaces or shared areas. • Stable indoor climate – NV Advance® opens and closes the windows gradually, ensuring a comfortable temperature and a consistent supply of fresh air throughout the day. • Central overview for the facility manager – integrated feedback to the BMS gives a clear picture of window positions, fault conditions and operation modes, which simplifies daily operation and troubleshooting. • Energy efficiency – by relying on natural ventilation for large parts of the year, mechanical systems are relieved, helping to reduce overall energy consumption. For the building’s users, the effect is tangible: fresh air, quieter automatic operation, and a more comfortable working environment that supports focus and wellbeing. For the owner and facility team, the system offers transparency, documentation and long-term operational reliability.
Circular thinking: giving old actuators a second life
The renovation also provided an opportunity to think beyond day-to-day operation and address what happens when components reach the end of their life cycle.
WindowMaster presented the option of using our take-back scheme for the building’s old hardware, working closely with HØGHØJ ApS to collect the actuators from the previous ventilation system and coordinate transport and processing. In total, 355 kg of old actuators were collected. The subsequent material flow analysis showed that:
- 88% of the materials went to recycling
- 11.7% were used for energy recovery
- Only 0.3% ended as landfill
The take-back solution is managed by POSIBI A/S, and the project forms part of an ongoing effort to understand how circular approaches to façade automation can be scaled up and create value on larger portfolios of buildings.
A healthier, more future-proof CUBE
With its renewed focus on natural ventilation, data-driven control and circular handling of components, The CUBE shows how an existing office building can be upgraded to deliver a modern indoor climate while respecting the original architecture. The atrium and façade design still do what they were meant to do – bring fresh air into the building and carry warm air out – but now they are supported by intelligent control, live feedback and a clear operational overview. The result is a more comfortable environment for tenants, a more manageable building for the facility team, and a stronger long-term investment for the owner.
