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Reimagining London’s Skyline: Maximizing Rooftop Space and Energy Efficiency at One Millennium Bridge

Landscaped rooftop of One Millennium Bridge in London

NDY, part of the Tetra Tech High Performance Buildings Group, elevated the London skyline by implementing ingenious rooftop solutions at One Millennium Bridge, achieving unmatched energy efficiency and optimizing space utilization at the 250,000-square-foot office building.


Owners Beltane Asset Management and Angelo Gordon (AG Beltane) recognized the wasted rooftop opportunities of One Millennium Bridge (formerly known as Millennium Bridge House), which boasted unparalleled views of iconic landmarks. A large heating, cooling, and ventilation plant occupied much of the space, hindering development of a unique rooftop restaurant and expansive terraces and causing disruptive noise for occupants and the surrounding community. Additionally, the building’s large gas-fired boilers on the rooftop raised environmental concerns. The client sought to eliminate combustible fuels on-site and contribute to London’s journey towards net-zero emissions.


Tetra Tech implemented thermal storage technology, typically used in the industrial sector, to optimize heating and cooling loads. By spreading these loads over a 24-hour period, smaller, more efficient plant systems could be employed, ensuring a quieter and more sustainable environment for occupants and the surrounding community. In a groundbreaking move, Tetra Tech replaced the gas-fired boilers with air source heat pumps, embracing a 100 percent electric solution that not only improved local air quality but also aligned with the client’s sustainability goals.


Tetra Tech’s ingenious solutions delivered a multitude of benefits for our client. The optimization of rooftop space enabled the creation of a unique rooftop restaurant, providing an exceptional amenity for building occupants and visitors. The reduction of peak loads and energy consumption significantly lowered operational costs, driving substantial cost savings for the client. Moreover, the shift to a 100 percent electric solution aligned the building with London’s sustainability objectives, contributing to a greener future for the city. By elevating London’s skyline with innovative technology, Tetra Tech’s work brought unmatched energy efficiency, enhanced occupant comfort, and minimized environmental impact, creating a landmark of sustainable development in the heart of the city.

One Millennium Bridge is designed to target BREEAM Excellent rating.

At a glance


AG Beltane

Completion date



Electrical, fire protection, plumbing, mechanical, sustainability consulting, vertical transportation, communications, smart buildings

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Seating area on rooftop of One Millennium Bridge in London
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