From structural challenge to high-quality facility

A masterclass in fast-tracked healthcare engineering, the £15m Ward 6 Ventilation Inpatient Centre (VIC) project at Aintree University Hospital Liverpool has transformed a high-risk structural challenge into a high-quality clinical facility, eradicating RAAC and completely reimagining the estate. As a result, the Major Capital Projects Team has created a facility that is now one of only four specially commissioned NHS Respiratory Weaning Centres in England. Kasia Pekala, senior project manager – Major Capital Projects Team at NHS University Hospitals of Liverpool Group, tells us more.

RAAC stands for Reinforced (contains steel bars) Autoclaved (process of making via Autoclave cooker) Aerated (contains bubble like structure) Concrete (mix of cement and aggregate). It is a lightweight, low strength concrete block used across the UK during the period of 1950s to mid-1990s. These structures were mainly used for building roof due to its good thermal properties. However, there have been cases were RAAC panels have also been used as wall structures.

RAAC has been extensively used in buildings such as schools, hospitals, and other public buildings due to its ease of installation, cost effectiveness, and speed of construction. However, between the 1980s and 1990s, RAAC has faced safety concerns related to its durability and lifecycle as cracking, sagging, and corrosion of steel reinforcement became evident.

Since 2019, the NHS has been surveying hospitals across the UK to identify the presence of RAAC. Once RAAC is confirmed on site, the Trust in question then follows a process of joining NHS England’s National programme for RAAC elimination. Our Aintree University Hospital at Liverpool is one of the sites with confirmed RAAC occurrence.

RAAC at Aintree University Hospital Liverpool

The RAAC at Aintree Hospital was discovered during structural surveys undertaken in 2018. Since then, our Property Team has been allocated the supervision of RAAC by creating a database and conduct condition surveys along with maintenance (i.e. using props if necessary). In addition, our Major Capital Projects Team has been assigned the task of managing a series of NHSE-funded RAAC eradications projects with the planned full RAAC elimination by the year 2032. At Aintree, we have eradicated RAAC from four hospital areas, with a total of 1,268 planks removed — a total area of 2,190 m². At present, RAAC is still to be removed from seven hospital buildings and areas with a total number of planks reaching 4,342 — a total area 5573 m² (with one building being still under investigation).

Due to high volume, complexity, and the scale of the scheme, a 10-year plan has been implemented to accommodate appropriate phasing, decants, and enabling works for smooth RAAC eradication between each area with a large focus being placed on RAAC condition and its severity.

Ward 6 and the impact of RAAC

Ward 6 — also known as the Ventilated Inpatient Centre (VIC) — was one of our facilities with RAAC roof presence. Ward 6 was part of our large-scale RAAC roof removal and elimination scheme and originally scheduled for project start on-site in 2026. Nevertheless, at the end of 2023, the Ward 6 project had to be brought forward when Liverpool was hit with terrible rain which lasted for several weeks. This severe weather ingress drastically compromised the RAAC roof deck below, with some planks being impacted by the water leaks. The project was fast-tracked and put into a state of emergency to relocate the patients and staff from the risk area.

The VIC is a 12-bed ventilation unit dedicated to treating patients with respiratory difficulties. The ward supports the population of Cheshire and Merseyside who require ongoing ventilatory support in the community.

The Major Capital Projects Team successfully refurbished an empty ward which then served as a temporary home for Ward 6.

Clinical enhancement scope

The primary objective of the project was to deliver a robust and compliant roof structure capable of supporting a newly installed plant room. The new plant room accommodates two Air Handling Units (AHUs), three Air Source Heat Pumps (ASHPs), water tanks, pumps, and a chiller. In addition, the project sought to provide modern clinical accommodation that complies with current Health Building Notes (HBNs), Health Technical Memoranda (HTMs), and Building Regulations.

The existing Ward 6 facility was not suitable for the long-term care of patients requiring specialist ventilation support. The VIC comprised an open-plan eight-bed bay with four individual bedrooms. While many patients remain in the VIC for several months, some require care for over a year. Given these extended lengths of stay, the existing accommodation did not provide the level of comfort, privacy, and dignity necessary to support patient wellbeing and recovery.

A key objective of the project was therefore to enhance the patient experience by providing only single-occupancy bedrooms, thereby improving privacy, comfort, and dignity. To further support patient independence and wellbeing, each bedroom was provided with its own en suite facility which was built as a wet room for the comfort of patients.

The VIC delivers two levels of care for vulnerable patients:

• Acute patients, who require non-invasive ventilation following respiratory infections such as influenza, COVID-19, or other respiratory illnesses.
• Weaning support patients, who require specialist support while being weaned from mechanical ventilation.

Weaning from mechanical ventilation is the gradual reduction of ventilator support as a patient’s respiratory function improves and they become increasingly able to breathe independently. Throughout this process, healthcare professionals closely monitor the patient’s breathing, oxygen saturation, heart rate, and overall clinical condition to ensure they can safely maintain adequate respiratory function without ventilatory assistance.

In addition to improving privacy and patient experience, the project focused on enhancing clinical functionality and service delivery. To achieve this, the ward was reconfigured to separate the two patient services, creating a dedicated acute care area comprising of eight single bedrooms and a dedicated weaning unit comprising of four single bedrooms.

Each bedroom has been designed to accommodate high-grade medical trunking with medical gases and single and double arm pendants.

Furthermore, Ward 6 was equipped with two bariatric bedrooms and seven ceiling-mounted hoist tracking systems. These facilities enable staff to provide safe, effective, and dignified care for patients with complex mobility requirements and support the needs of some of the Centre’s most vulnerable patients.

“The unit is all single rooms with en suite facilities and will allow us to receive patients rapidly from the emergency department, freeing up resus,” explains Dr Robert M. Angus — consultant respiratory physician and medical lead for ventilation at Aintree University Hospital. “In the old facility we could not do this until swabs were clear; this contributed to flow challenges. This is a good investment by the Trust of NHS funds and will see improved patient care.

“The technical side of the build is impressive. The air handling and temperature control systems are state of the art and deliver a facility which will be pleasant for patients and allow the management of infection control issues effectively. When we face another pandemic, we will be much better equipped to handle it. The systems employed use some of the best technology available and helps the hospital achieve the priorities of a green NHS.”

Working closely with the design team, we reimagined and redesigned the existing ward layout. Despite retaining the same overall floor area, the new design significantly improves the sense of space, creating a more open, functional, and patient-centred environment that feels considerably larger and less constrained than the previous arrangement.

Location

Ward 6 is located in one of the busiest areas of the hospital, situated adjacent to the main entrance and surrounded by several critical departments, including the Accident & Emergency Department (A&E), Outpatients Department, Radiology, and the Critical Care Unit.

In addition, the works were carried out close to the hospital helipad, requiring close coordination with the security team. Construction activities were temporarily paused whenever a helicopter was arriving or departing to ensure the safety of patients, staff, contractors, and flight operations.

The project’s location adjacent to high-acuity clinical areas presented significant challenges, requiring works to be delivered within a live hospital environment while minimising disruption to critical services. Effective collaboration, weekly coordination meetings, and a consistent on-site contractor presence were key to the successful delivery of the project.

Existing structure

a) Radiology roof and timber guttering

Working adjacent to the Radiology Department roof presented one of the greatest challenges of the project. The roof is constructed from RAAC, which significantly limited access and imposed strict loading restrictions. Working closely with the design team, including Arcadis (Architects), Curtins (Structural Engineers), and specialist subcontractors, a solution was developed to minimise any impact on the existing roof structure:

•  Scaffold solution: Access to the rear elevation of Ward 6, facing the Radiology Department, was achieved without imposing loads on the RAAC roof. A bespoke ‘horse’ scaffold was installed from within the first floor of the VIC, creating a cantilevered structure externally. The scaffold relied on the structural strength of the building’s walls and floors, providing safe access for construction works while avoiding any load transfer to the roof.
• Safe Roof Access: Youngman boards were utilised to create designated safe access routes across areas of RAAC roofing. Following structural assessments by Curtins, suitable routes were identified for personnel movement and the placement of lightweight materials lifted by crane, ensuring safe operations while protecting the integrity of the roof structure.

Besides the roof replacement, leaks from the existing timber gutter located at the rear of Ward 6 also required attention. The proposed solution was the installation of a reinforced, multi-layer liquid plastic system to enhance long-term watertightness and improve resilience at this critical junction.

b) Existing structural frame and foundations

Lightweight concrete was fundamental to the structural strategy, substantially reducing the roof’s permanent dead load compared with a conventional concrete solution. This weight reduction was critical to retaining the existing structural frame and foundations while creating sufficient capacity for the extensive new rooftop plant, thereby avoiding more intrusive strengthening and reconstruction works within the operational hospital.

c) Existing drainage replacement

The existing Ward 6 drainage system required major upgrades, including the replacement of several discharge stacks. Due to the increased number of stacks proposed, overnight surveys and close coordination with Trust office teams were necessary to facilitate core drilling and the installation of new drainage connections with minimal disruption.

Phasing of the RAAC roof removal and demolition

Roof replacement was divided into four controlled phases beneath two moveable temporary roof tents. Their configuration was governed by the limited capacity of the retained Level 1 floor — approximately 5.0 kN/m² along the central spine and 2.5 kN/m² within two perimeter zones — and the adjoining Radiology RAAC roof. A front birdcage/crash-deck established a direct load path, while a cantilevered rear ‘horse’ scaffold avoided applying reactions directly to the Radiology panels. The tents maintained a weather-protected enclosure and were repositioned in coordination with suitable wind conditions, crane operations and the steelwork programme.

With the incorporation of lightweight concrete, the completed roof forms a stiff, non-combustible diaphragm designed to Consequence Class 2B, steelwork Execution Class EXC2, 60-minute fire resistance, and a 50-year working life.

Each demolition phase followed a repeatable sequence: existing cladding, roof finishes, and insulation. Redundant plant and parapets were removed. RAAC planks and existing steelwork were dismantled progressively, working gridline by gridline to preserve stability. Temporary bracing was installed before critical members were removed. New steelwork was integrated with the retained concrete ring beams, followed by replacement castellated beams, trimmers, parapet and plant-support steel. Met Floor 80 decking, welded shear studs, A252 reinforcement, lightweight concrete, and formed service upstands completed the composite slab before waterproofing and roof finishes were applied.

Ventilation focused service enhancement

Ventilation played a crucial role in the project, as our objective was to deliver a high-quality, safe respiratory ward. As previously mentioned, Ward 6 provides both acute and weaning care for vulnerable respiratory patients. The ventilation system was therefore designed to serve each area according to its specific clinical requirements.

All rooms within the VIC are mechanically ventilated, with cooled air supplied at a constant temperature of 16°C. Air is delivered to patient rooms via two new air handling units, each dedicated to serving the acute and weaning ward.

The acute patient bedrooms are designed as neutral-pressure rooms, where air is supplied at a constant rate and regulated by Constant Air Volume (CAV) dampers to maintain the required airflow.

In contrast, the weaning bedrooms have been upgraded to provide greater operational flexibility. In addition to supporting weaning services, these rooms can also be utilised as acute care beds during periods of increased winter pressures. This is achieved by using Variable Air Volume (VAV) dampers, which regulate extract airflow rates within the rooms, while ventilation rates to adjacent corridor areas are adjusted accordingly.

Sustainable application and use of Air Source Heat Pumps

The project incorporates a sustainable energy solution using Air Source Heat Pumps (ASHPs), which provide heating, cooling, and domestic hot water for the ward. The VIC has been equipped with three Airedale AlphaChill Plus ACHP P55.4 units. The primary objective was to eliminate reliance on gas-fired heating while also providing an efficient cooling solution.

Each P55.4 unit delivers approximately 150 kW of nominal heating capacity and 139 kW of nominal cooling capacity from a reversible air-to-water heat pump. At Airedale’s published rating conditions, the unit achieves a heating Coefficient of Performance (COP) of 3.17, with Seasonal Coefficients of Performance (SCOP) of 4.15 at W35 and 2.96 at W55.

The adoption of this ASHP technology provides several key benefits:

• Significant reduction in operational carbon emissions through the replacement of natural gas heating with electrically driven heat pumps.
• Provision of both heating and cooling from a single plant system, reducing the need for separate boiler and chiller installations.
• High efficiency at lower water temperatures, making the system particularly suitable where ward emitters and air handling units operate at 35°C to 45°C rather than the traditional 70°C to 80°C associated with boiler systems.
• Hot water production up to 60°C, providing flexibility while maintaining good overall efficiency.
• Inverter-driven operation, allowing the units to modulate output in line with demand rather than continuously cycling compressors.
• Dual refrigerant circuits, improving system resilience compared to single-circuit alternatives.
• Use of R32 refrigerant, which has a Global Warming Potential (GWP) of 675 and zero ozone depletion potential. Airedale also states that the design requires approximately 16 per cent less refrigerant volume per kW than an equivalent R410A system.
• Low operational noise levels, with the P55.4 rated at approximately 54.6 dB(A) at 10 metres, making it well-suited for healthcare environments where plant is located close to wards, patient bedrooms, or neighbouring properties.
• Support for NHS decarbonisation objectives through the reduction of fossil fuel consumption and associated carbon emissions.

Using the government’s 2026 greenhouse gas conversion factors, published in June 2026, it is possible to estimate the carbon emission savings achieved through the Ward 6 upgrade. A breakdown of the estimated carbon reduction is provided in the table shown above.

Replacing a conventional natural gas boiler operating at 90 per cent efficiency with an AlphaChill Plus ACHP P55.4 Air Source Heat Pump could reduce operational heating-related carbon emissions by approximately 78 per cent to 84 per cent, based on current UK grid carbon factors. The level of carbon reduction achieved depends primarily on the heating water temperature and the SCOP attained in operation. Nevertheless, the adoption of this technology represents a substantial reduction in CO₂ emissions and makes a significant contribution towards the NHS’ Net Zero carbon objectives.

Electrical improvements UPS including IPS system

The Ward 6 Main Distribution is fed via A&B supplies alongside a standby generator with UPS’s offering support during any given change over from Supply A to Supply B, Mains Changeover to Back up Supply.

The changeovers locally to selected distribution are supplied through Manual Transfer Switches giving the option of A or B preference.

Two UPS systems (A and B) were introduced in line with the changeover requirements provided by the main switchgear. Each 60 kVA unit is fully compliant with HTM 06-01 and provides 60 minutes of battery autonomy. The UPS systems operate in an N+N parallel redundant configuration, maintaining an output of 48 kW for up to 60 minutes at a power factor of 0.8. They also provide overload capacity of 125 per cent for 10 minutes and 150 per cent for 1 minute, ensuring resilience during periods of increased demand.

In addition to supporting the electrical distribution network, the UPS systems provide power continuity to the Isolated Power Systems (IPS), which serve critical clinical equipment such as ventilators, patient monitors, and other essential medical devices.

The IPS installation comprises 8 kVA, 230 V single-phase isolating transformers equipped with static shields. Distribution circuits are protected by 20 A double-pole miniature circuit breakers (MCBs) housed within floor-mounted IPS enclosures.

The Ward is supported by these resilient electrical systems, alongside a range of specialist building services that ensure the safe and effective operation of the VIC. These include general and emergency lighting, power distribution, heating and ventilation systems, life-safety systems, and the critical medical equipment required to deliver high-quality patient care and support recovery.

Collaboration as a key to successful project delivery

The successful delivery of this project was driven by strong stakeholder engagement, led by the senior project manager (myself) and close collaboration between the Trust, Tilbury Douglas, and the wider design team. Regular communication and proactive coordination ensured operational requirements were met while minimising disruption within the live hospital environment. Key stakeholders included Ward 6 clinical staff (Rebecca McAlinden, Liam Campbell, Dr Robert Angus), Estates, Infection Prevention and Control (IPC), Security, IT, Medical Equipment, Domestic Services, and other departments impacted by and contributing to the project.

“A key strength of the project was the collaborative engagement with the clinical team,” says Liam Campbell — advanced practice physiotherapist in long term ventilation and weaning. “Opportunities for site visits and walkthroughs were facilitated, ensuring that frontline staff were involved and informed, and that the final design reflected the operational needs of the service. This inclusive approach helped to build confidence and readiness ahead of the transition to the new ward environment.”

“Tilbury Douglas have delivered a challenging project within a complex live hospital environment, with the site positioned between key critical areas,” explains Dave Booth — senior project manager at Tilbury Douglas. “Throughout the works, the team maintained excellent communication and collaboration with all parties, helping to minimise disruption while keeping the needs of patients, staff, and visitors at the forefront. Their proactive approach and understanding of the operational pressures within a busy acute hospital setting have been greatly valued.”

Equally important was the contribution of the multidisciplinary design and delivery team, comprising of Arcadis (architects — team consisted of Rachel Bruce, Neil Donelon, Victoria Rice, Aldibani Taha), Curtins (structural engineers — Dave Jones), Steven Hunt Associates (mechanical and electrical designers — Edward Raven, Neil Baines), and Tilbury Douglas (principal contractor — Ben McDermott, Dave Jones, Chris Garner, Cheryl Watt, Ishtiaq Ahmed, Simon Davies, Paul Clitheroe, Ryan Taylor). Their collaborative approach enabled challenges to be identified and resolved quickly, ensuring effective solutions were developed and implemented within the constraints of a live hospital environment. This was particularly important given the need to deliver the project at pace while maintaining patient safety and minimising disruption to essential clinical services.

“Delivering Ward 6 has been one of the most complex and rewarding RAAC projects we’ve worked on, and we’re proud to have helped create an improved facility for Aintree Hospital,” says Rachel Bruce — associate principal — studio manager at Arcadis Consulting (UK).

“Working together with Tilbury Douglas gave us the opportunity to solve complex logistical and design challenges that the existing structure presented, with the support of Curtins, enabled us to retain the existing structure to provide an improved facility for the community.

“Engaging with the staff user group was invaluable and fundamentally shaped how the ward needed to function to provide the highest standard of care for patients — we are pleased to see that they are enjoying their new space!”

Conclusion

Internally, Ward 6 has been transformed from an open-plan ward with limited privacy, sanitary facilities, and specialist respiratory capability into a modern Ventilation Inpatient Centre. The reconfigured layout provides four dedicated weaning rooms for highly dependent patients, eight single inpatient bedrooms, enhanced WC facilities, and improved separation between patient acute and weaning areas. Modern medical equipment, high-efficiency filtration, heat recovery systems, and room-level environmental controls support safer, more comfortable care while strengthening infection prevention measures in line with HTM guidance.

Ward 6 demonstrates the value of collaborative healthcare construction. Through careful phasing, robust temporary works, and the swift resolution of structural and waterproofing challenges, the team successfully eliminated the RAAC risk while delivering a safe, resilient, and future-proof clinical environment. This significant transformation was achieved within a live hospital setting, protecting neighbouring services and maintaining the Trust’s operational priorities throughout.

We hope to deliver many more projects like this in the future.