20 Gresham Street – Full BMS Installation and BACnet Integration

Alpha Controls were tasked with carrying out a complete BMS installation for a multi-floor commercial office building in the City of London. The project required a new open-protocol control network, integration of existing equipment, and the replacement of outdated control infrastructure — all delivered over a three-month phased schedule, aligned with the client's construction programme as areas became ready.

Our engineers coordinated installations across active zones, ensuring each area was commissioned and functional before handover whilst maintaining the client's timeline and avoiding disruption to parallel trades.

The new system was designed around an Automated Logic platform, using controllers to manage fan coil units (FCUs), variable air volume boxes (VAVs), and environmental plant. Over 250 FCU points were connected and commissioned across all five levels, forming the core of the building's comfort-control network.

Communication between all controllers and metering devices runs on a BACnet/IP backbone, giving the client a fully interoperable system with the flexibility to integrate future equipment and expansions.

As part of the installation, Alpha Controls integrated an extensive range of plant and field devices, ensuring full visibility of all mechanical systems from the central BMS interface. Key integrations included:

• Underfloor heating setpoints and temperature monitoring
• CO₂ and pipe temperature sensors across all floors
• Extract fans and local air-handling components
• Water conditioners and calorifiers
• Smoke and fire dampers (enable/disable and fault monitoring)
• Water meters and the wider metering network for consumption reporting

All new sensors and transducers were supplied and installed using Sontay field devices, recognised for their robust build quality and dependable performance in commercial environments. Their accurate data feedback supports stable temperature control, efficient scheduling, and consistent environmental performance.

Each of the five floors was divided into four control zones, allowing efficient scheduling and fine-tuned temperature control within occupied areas. The Automated Logic controllers manage local FCU and VAV units via BACnet, whilst plant systems and metering data are routed back to the main BMS panel for global monitoring and trending.

A new metering network was established and connected through the BACnet backbone, giving live visibility of electrical, water, and thermal energy data. All meters were configured for trending, allowing the facilities team to analyse usage by floor or zone and identify opportunities for optimisation.

The system's open-protocol design ensures that future meters or energy sub-systems can be added without requiring proprietary gateways, keeping the installation scalable and future-ready.

The installation was carried out over three months, working around the main contractor's phased release of areas. Alpha Controls' team managed the full process — from field device wiring and control panel assembly to final software commissioning and functional testing. Our engineers returned floor by floor as fit-out works progressed, ensuring that each zone was fully functional, commissioned, and witnessed before handover.

The BMS network was then integrated and validated as a complete system, confirming end-to-end communication between all field controllers, sensors, and the central supervisor.

The completed BMS at 20 Gresham Street provides:

• Full monitoring and control of HVAC, metering, and plant systems
• Open-protocol BACnet communication for long-term flexibility
• Reliable data from robust Sontay sensors and field devices
• Improved occupant comfort through precise FCU and VAV control
• Comprehensive metering visibility for ongoing energy management

This project demonstrates Alpha Controls' ability to deliver large-scale, technically complex BMS installations within tight timelines, coordinating across multiple trades and system types.