Dowds Group, a UK-based construction company, was appointed by the main contractor, McLaren, to deliver the mechanical, electrical, and plumbing (MEP) engineering services for Queen Elizabeth Hospital, part of the Lewisham and Greenwich NHS Trust.
Dowds Group started the £30m sitewide infrastructure project in August 2022, and consulting engineers, DSSR, were also a part of the project, which reached practical completion in August 2024.
The scale and complexity of the works set a new benchmark for live infrastructure projects in healthcare
The scale and complexity of the works set a new benchmark for live infrastructure projects in healthcare, showcasing innovative solutions and meticulous planning to ensure uninterrupted hospital operations throughout.
Dowds Group exclusively shared with Building Better Healthcare the methods used in the most extensive, site-wide infrastructure upgrade ever undertaken for a fully operational NHS hospital in the UK.
Modern methods of construction and unique features in the build
4-in-1 Air Handling Unit
The most unique feature of the project was the innovative modular compact Air Handling Unit (AHU) enclosure, specifically designed to serve four independent operating theatres within a single, compact module.
Each theatre is able to maintain its unique air handling requirements—such as temperature, humidity, and filtration—while occupying a much smaller footprint, unlike traditional systems that require separate AHUs for each theatre.
This unique 4-in-1 approach was first implemented in Queen Elizabeth Hospital and had never been attempted before.
This unique 4-in-1 approach was first implemented in Queen Elizabeth Hospital and had never been attempted before
This cutting-edge design also aligns with the updated Health Technical Memorandum (HTM) 03-01 (2021), which establishes rigorous standards for specialised ventilation in healthcare settings. The 2021 update, which supersedes previous guidelines (HTM 03-01, HTM 2025 [1994], and DV4 [1983]), reflects advancements in air quality standards and infection control—critical factors for operating theatres.
By complying with HTM 03-01 (2021), these AHUs ensure optimal airflow, advanced filtration, and enhanced safety, meeting the highest standards for both healthcare professionals and patient safety protocols.
The AHU in the factory
Key benefits of the AHU include:
- Space efficiency: Consolidating multiple AHUs into a single compact enclosure saves valuable space in the hospital, where room is often limited.
- Streamlined installation: The off-site construction and modular design minimized disruption, which was essential as the project took place in a live hospital environment.
- Cost and energy efficiency: Integrating systems into one module reduces operational costs and improves energy performance.
- Simplified maintenance: Maintenance is easier and less invasive, further supporting the hospital’s ongoing operations.
Additionally, the HTM-compliant packaged AHUs with integral enclosures were manufactured and delivered entirely off-site by a specialist supply chain partner. This ensured the highest quality and compliance while significantly reducing on-site complexity.
This setup is particularly beneficial for hospitals seeking to modernise or expand their facilities without requiring significant structural changes. By supporting enhanced airflow control and energy efficiency in a compact, integrated design, this 4-in-1 AHU enclosure is setting a new standard for healthcare ventilation systems.
Resin Busbar system
Dowds Group installed a state-of-the-art Resin Busbar system throughout the hospital to support the current and future electrical switch panels without any disruption to staff or patients despite the complexities of working in a live hospital environment.
The Resin Busbar System is an advanced electrical distribution system used primarily in high-performance and demanding environments, such as hospitals. It offers a modern, efficient, and safe alternative to traditional cable-based systems.
The Resin Busbar System is an advanced electrical distribution system
"Traditionally, multiple cables would have been required to feed individual panels, but this busbar system offers a highly efficient, future-proofed solution, providing over 50% spare capacity in some areas and up to 100% in others," a Dowds spokesperson explained.
The Resin Busbar system is also a significant asset for the hospital's infrastructure, as a 1000-meter HV diverse ring was constructed around the hospital’s perimeter to support two new 11,000 kVA transformers, complemented by three new 1.5 MW generators. In the event of a power outage, this setup enables an uninterrupted transition to generator power via the G99 relay, ensuring that the hospital remains fully operational without any interruptions.
Overcoming challenges in the build
The biggest challenge faced by the team, including the project partners, was ensuring that the hospital remained fully operational throughout the project.
All work required careful scheduling, with up to 12 weeks’ notice provided to the Trust to allow for theatre and operation planning without disruption.
Due to restrictions on the live site, crane lifts for moving plant equipment on or off the building were not permitted
Each shutdown was meticulously coordinated and strictly adhered to, with full cooperation from the on-site facilities management (FM) team, and many shutdowns were completed outside of standard hours to minimise impact during critical periods, and in some cases, temporary power and equipment were used to maintain essential services, according to the Dowds Group spokesperson.
Further, due to restrictions on the live site, crane lifts for moving plant equipment on or off the building were not permitted. This was further complicated by the roof’s limited safe working load of only 400 kg per square metre.
The last challenge the team overcame was designing the 4-in-1 Theatre AHU enclosure required precise attention to module sectioning, size, and weight to ensure safe handling. Each section was carefully sized for a small team to manoeuvre from curbside to the roof, first by a small material hoist, and then into the plant room, where the unit would be assembled.
Technological innovations integrated into the build
As part of the upgrades to the hospital’s medical gas oxygen system, Dowds Group installed a new oxygen system that includes a secondary VIE compound. This additional VIE compound ensures a redundant oxygen supply to the hospital, guaranteeing continuity in the event of any failure with the existing compound.
A new ring main was also installed, along with additional oxygen terminal outlets in most wards, providing critical extra access points for patient care. All work within the wards was completed one bay at a time, allowing them to remain fully operational throughout the installation.
Dowds Group installed three new N+1 backup generators and bulk fuel tanks capable of delivering 1.5 MW of power for up to 200 hours
In addition, Dowds Group installed three new N+1 backup generators and bulk fuel tanks capable of delivering 1.5 MW of power for up to 200 hours. The generators are integrated with a comprehensive PLC system, which monitors all incoming and outgoing power supplies and controls circuit breakers that are displayed on the head-end interface in the FM team’s office.
This robust system enables the hospital to maintain full functionality during any power outages,
ensuring uninterrupted patient care under all circumstances.
Sustainability factors in the build
To reduce energy consumption, the project involved modernising the plant and equipment that were over 30 years old, with more efficient solutions. Instead of completely replacing the AHUs, the Trust opted for a more commercially viable refurbishment approach.
Since fully upgrading the units to current HTM standards was not feasible, Dowds Group enhanced the existing units by installing new G4 panel filters, F7 filters, and N+1 high-efficiency EC fans. This combination of targeted refurbishment and the addition of high-efficiency EC fans resulted in a significant load reduction and energy savings across 14 units.
This combination of targeted refurbishment and the addition of high-efficiency EC fans resulted in a significant load reduction and energy savings across 14 units
Given that hospital AHUs operate 24/7 throughout the year, this approach delivers substantial annual reductions in both energy consumption and carbon emissions.
Dowds Group is currently validating the precise percentage of savings per unit and per kWh, quantifying the exact energy benefits realised through this refurbishment strategy.
The final result
Overall, Dowds Group and its partners delivered a groundbreaking hospital that can serve as a model for future healthcare projects, shaping the future of hospital infrastructure with an unwavering focus on quality, sustainability, and innovation.
Preconstruction Director, Dowds Group, Chris Argent, said: "This project at Queen Elizabeth Hospital represents a significant achievement for the Dowds Group, highlighting our commitment to delivering innovative and practical engineering solutions, even in the most challenging environments.
The HTM-compliant packaged AHUs with integral enclosures were manufactured and delivered entirely off-site by a specialist supply chain partner
"Our team took great pride in developing and installing the UK's first-ever 4-in-1 compact air handling unit enclosure, which serves multiple operating theatres. Our modular approach allowed us to meet the client's needs for weight constraints, space efficiency, sustainability, and seamless operation within the UCV operating theatres.
"Furthermore, our team played a crucial role in upgrading the medical gas oxygen system, ensuring a diverse and secure oxygen supply to the hospital. At the same time, installing three N+1 backup generators provides a robust backup supply, which is crucial for maintaining uninterrupted hospital operations. Despite the complexities of working in an active hospital setting, our dedication to precision and safety ensured the project was completed to the
highest standards, setting a new benchmark for future healthcare infrastructure projects in the UK."
Top image: Queen Elizabeth Hospital Images courtesy of Dowds Group
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