Woodmill & St Columba's RC High Schools

Location: Dunfermline, Fife
Completion Status: 2024	Occupancy: 2024
Architect: AHR	Consultant: AHR
Contractor: BAM Construction	Client: Fife Council
Certification: Passivhaus Classic, 2025	Certifier: WARM
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The Woodmill & St Columba's RC High Schools on the new Dunfermline Learning Campus have many claims to fame. Currently the UK's largest Passivhaus certified building, the Fife Council schools are co-located in one single building that has a combined treated floor area of 23,151 m². As well as being the first certified Passivhaus secondary schools in Scotland, the project also lays claim to currently being the world's largest Passivhaus educational building.

Designed by PHT member AHR, certified by PHT Patron WARM, with PHT member AECOM as structural engineer, the project is a Pathfinder project for Scotland's Net Zero Public Sector Building Standard.

We want to provide a lasting educational legacy for future generations, supporting and improving the whole learning environment whilst also helping us meet our net zero obligations.

Alan Paul, Head of Property Services, Fife Council

Good form factor was an important early consideration. The project team was keen to keep the form of the large building as compact as possible. Merging both high schools into one single building allowed for a highly efficient form factor thus reducing the building fabric heat loss area. Three internal courtyards were introduced to ensure natural ventilation and daylight reach the building’s deep plan zones.

Key stats

Construction: Precast concrete frame, CLT & steel frame
Number of occupants (pupils/ staff): 2,759
Gross internal floor area (GIFA): 26,666 m²
Treated floor area (TFA): 23,151 m²
Form factor: 1.7
Build start date: 2022
Completion date: August 2024
Certification: Passivhaus Classic, 2025

Woodmill & St Columba's RC High Schools, Dunfermline. Image credit: AHR & Keith Hunter Photography

Construction

The building combines three construction types for different elements of the building.

Precast concrete frame

The teaching wings comprise a three storey precast concrete frame with load bearing precast walls and columns supporting precast hollowcore slabs, with structural concrete topping.

Precast concrete frame & steel frame

The building's central core (excluding the dining area) comprises a two storey braced steel frame, supporting precast hollowcore slabs with structural concrete topping.

CLT panels

The sports block is a two storey CLT frame. The upper floor and roof deck are formed with CLT, supported by loadbearing CLT walls.

The specification of precast concrete frame and CLT frame aimed to help simplify the achievement of airtightness targets on site. The integration of the three structural frames - precast concrete, cross-laminated timber (CLT), and steel frames - has required detailed coordination to ensure airtightness and thermal performance is maintained. Particular challenges arose around movement joints and the interfaces between structural systems.

CLT was selected for the sports block due to poor ground conditions that were unsuitable for the weight of a precast frame. Although the original ambition was for full CLT across the entire building, material supply limitations required a hybrid solution.

Steel was introduced in the central core to accommodate large spans and improve buildability. At the time, steel was not widely used in Passivhaus design, necessitating detailed thermal bridge modelling and careful design of junctions to maintain the thermal envelope performance.

Embodied carbon

Embodied carbon targets were aiming for a budget of under 650kg/CO₂e/m^2,as per RIBA 2025 Target and the Net Zero Carbon Public Sector Building Standard. The use of CLT significantly contributed to a lower embodied carbon footprint, achieving a final value of 626 kgCO₂e/m². Recycled content in concrete also played a role in achieving this target.

Services

Ventilation: The ventilation system adopted a cascade approach, where multiple rooms share roof mounted Passivhaus MVHR units with centralised extract points via bell-mouth ducts in the corridors. Some specialist rooms, such as CDT and home economics, are served by dedicated Passivhaus MVHR units. In the sports block, each hall is served by a standalone unit, allowing for independent operation. Where possible, the central MVHR systems are arranged in a cascade arrangement, which has allowed air volumes to be minimised by transferring fresh air between spaces where the synergy of occupancy permits. The air handling systems are zoned to suit school/ community use, facilitating areas being shut off when not in use.

Heating: A series of modular air source heat pumps (ASHP) are used to heat the building. The school is heated by a mix of heating modes, including radiant panels and underfloor heating. Underfloor heating is restricted to the ground floor, generally serving large volume areas. Radiant panel solutions have been developed for the general and technical teaching spaces. The building has been divided into zones with separate systems for each zone provided to minimise the extent of the distribution network. The heat pump systems are sized to suit the low heat loss demand of the Passivhaus building, allowing pipework distribution systems and heat emitter sizing to be optimised.

Hot water strategy: Hot water demand is met via centralised systems only where necessary, such as in the kitchen and changing rooms. Elsewhere, instantaneous electric heaters beneath individual sinks eliminate the need for extensive hot water pipework, reducing heat losses associated with long pipe runs.

Summer comfort: The design maximises on the north and south-facing façades allowing effective control of the overheating risk. Glazing is generous to these facades to maximise on the daylighting into the internal spaces. Solar shading strategies include horizontal brise-soleils mounted on the southern elevation to all windows and vertical shading fins on the east and west facades. Shading canopies are used around the main east-facing glazed entrance and along some teaching rooms.

Building performance

Woodmill & St Columba's RC High Schools, Dunfermline. Image credit: AHR & Keith Hunter Photography

Designed energy performance

Main building

Sports block

Airtightness n₅₀ (≤ 0.6 ACH @ 50 Pa)

0.45 ACH @ 50 Pa

Space Heating Demand (≤ 15 kWh/m².a)

14 kWh/m².a

13 kWh/m².a

Heating Load (≤ 10 W/m²)

8 W/m²

9 W/m²

Primary Energy Renewable (PER) Demand (≤ 60 kWh/m².a*)

68 kWh/m².yr (verification under PER)

67 kWh/m².yr (verification under PER)

Primary Energy Renewable Generation

22 kWh/m².a

9 kWh/m².a

*+/-15 kWh/m².a allowance if offset by energy generation. See Passivhaus criteria.

Woodmill & St Columba's RC High Schools, Dunfermline. Image credit: AHR & Keith Hunter Photography

U-values

Element

Main building (precast concrete)

Sport block (CLT)

Floor

Ground bearing concrete slab with underslab insulation

U-value: 0.103 – 0.142 W/m²K

Ground floor concrete slab with above slab insulation and floor screed

U-value :0.106 - 0.114 W/m²K

Wall

Precast concrete frame. External cavity mineral wool insulation wall with facing brick and vertical seamed aluminium cladding (unvented) with insulation

U-value: 0.125 - 0.135 W/m²K

CLT frame. External cavity mineral wool insulation wall with facing brick and vertical seamed aluminium cladding (unvented) with insulation

U-value :0.126 - 0.148 W/m²K

Roof

Inverted roof with insulation on waterproofing on concrete structural topping

U-value: 0.102 W/m²K

Inverted roof with insulation on waterproofing on CLT planks.

U-value: 0.093 W/m²K

Architect’s view

In order to achieve the Passivhaus standard on a building of this scale, it was essential that we were guided by Passivhaus principles from the outset. Although Passivhaus is a fundamental and integral part of the design approach to the new school, design quality was always at the forefront of any decisions made. Following the Scottish Funding Trust’s Energy in Use requirements, the building was designed to a stringent set of criteria to ensure maximum comfort with minimum overall energy consumption, designing to the Passivhaus standard guaranteed we met the Energy in Use criteria.

Jamie Gregory, Passivhaus Designer & Project Architect, AHR

Challenges & lessons learned

The project team has shared its key lessons from undertaking the largescale Passivhaus educational project:

Early stage design: Passivhaus needs to be integrated into the architectural design from the start and cannot be a 'bolt-on'. Consideration of key Passivhaus criteria early on in the design development stage was critical. The adoption of the principles of orientation and building form were low cost and high impact elements of the design. Using Passivhaus Planning Package (PHPP) was a powerful design tool to quickly understand design change impacts.
Airtightness strategy: The simpler the strategy the easier it was to deliver on site. Making the airtight line simple and easy to track assisted the on-site works. The use of CLT and precast concrete frames helped make the build process more straightforward, because the airtight line was simpler and easier to understand. Minimising the use of the steel frame in the project minimised the requirement for more complex detailing.

Construction training: It was important for all construction site operatives to understand Passivhaus build quality requirements, and additional training was delivered on site. Attention to detail and quality assurance on site around airtightness detailing and the insulation installation was critical to the building’s overall performance. The quality of the installation of heating and hot water pipework, including its insulation, was also of critical importance.
Roof-based ‘dog boxes’ for MEP: To route mechanical services into the building while maintaining airtightness and a continuous thermal line, CLT 'dog boxes' were constructed on the roof. Each unit was uniquely designed to integrate with the ductwork layout.

Embodied carbon: Lessons from this project have informed the subsequent design of Caledonia High School, in Rosyth, Fife, which uses green steel for a majority of its structure to further reduce embodied carbon across the structure.

Key team

Clients: Fife Council

Architects & Passivhaus Designers: AHR Architects

Contractors: BAM Construction

M&E Design: Rybka

Structural Engineer: AECOM

Landscape Architects: Oobe

Product suppliers: Metal Technology Ltd

Passivhaus Certisfier: WARM

A massive congratulations to the whole team on their mega-campus Passivhaus certification achievement, putting Dunfermline and Scottish Passivhaus schools firmly on the global map.