THE PROJECT
The design and construction of a nine classroom, cross laminated timber (CLT) framed secondary school, arranged over two storeys, creating 1912m² of new new floor space with reception, administration rooms, performance area and canteen including associated external works and drainage.
A crane was used to put each piece of CLT in position. The structure also includes brickwork and the roof finish is a Bauder Single Ply membrane on top of a structural timber deck (circa 700m²), along with two pitched euroclad roofs (circa 250m²).
Classrooms have been installed above the café space, with three more classrooms downstairs. Each provides a light, airy space for teaching with underfloor heating, mechanical ventilation, wi-fi and a teaching wall with screen and storage for resources.
Stakeholder engagement
We held weekly ‘site-walks’ with the Client, Governors and primary Stakeholders from day one of the project inviting various personnel to site to keep them updated with progress and key milestones.
We also held numerous events and open site-walks with the key pupil groups including a brick signing event, interactive videos, topping out ceremony and an industry talk which gave the pupils ideas to help design the furniture and configure the layouts. The weekly updates provided a good opportunity for collaboration with all parties involved in the project.
Working near the existing Nursery & Primary School
The site location itself was in close proximity to the neighbouring buildings & had reduced access around the perimeter. Therefore, it was critical to erect & maintain a solid hoarding throughout the build.
We formed viewing galleries allowing the pupils, staff and parents an insight to site activities. Our Health and Safety Phase Plan was regularly updated through Health and safety workshops and collaboration with the School.
Importing the CLT frame from Austria to site
The current climate imposed a challenge with the import of the CLT structure from Austria to site. We received circa fifteen large deliveries from Austria which we had to meticulously manage to site via the UK ports for arrival to site ‘just in time.’ We mapped out the traffic route of the deliveries & ensured the procurement of the CLT was delivered to always keep the crane and workforce in full operation.
11.2%
on-site energy generation
2.96 m³/h.m²
Air tightness at 50pa
30.17kwh/m²/yr
Heating & hot water load
0.37w/m²k
Overall area weighted u-value
10.8kg C02 eq/m²
Annual C02 emissions
A
EPC rating
The construction process has been a great source of educational stimulation for our students transitioning to the Senior School, staff and governors. We have all learnt a great deal from our site walks (including a brick signing event), interactive videos and attending the topping-out ceremony. The engaging industry talk encouraged pupils’ ideas which shaped the furniture design and room layouts."
SCHOOL GOVERNOR, Crosfields School
DIGITAL MINDSET
Based on the client, project manager and lead designer’s ambitions, the project was set up to be exemplar in terms of design quality, collaboration, project management excellence and sustainability.
Our collective early commitment to BIM Level 2 protocols, including working in a common data environment, use of digital design techniques and combining this with MMC and Cross Laminated Timber (CLT) was fundamental to realising this vision.
Early engagement with key sub-contractors was key, as well as a team that were highly collaborative and innovative, embracing the benefits of a digital workflow combined with off-site manufacture to deliver project excellence.
A fully developed Building Information Model (BIM) was issued at an early stage, which allowed:
- Coordination with the CLT supplier to ensure accuracy of information during pre-fabrication of CLT panels and cost certainty for the client.
- Clear communication of phasing and design options to all stakeholders using realistic, comprehensive walk-throughs and animations.
This helped achieve design approval in a timely and cost effective manner and ensured the safest and most efficient site planning. This was particularly important because the school had to remain open and operational throughout construction.
This innovative approach proved to be the lifeline for the project’s success as it enabled us to mitigate a 3-month delay in starting on site when the pandemic struck.
Typically MMC suggests economies through repeatability. However, at Crosfields standard digital design processes combined with MMC allowed mass customisation and a highly bespoke response to the client brief, rather than an off-the-peg solution.
CARBON REDUCTION
The use of CLT contributes to both reduced energy requirements in the running of the school and reduced carbon in the build. CLT reduced substructure works, meaning less concrete and construction traffic (protecting air quality). It reduced embodied carbon by almost 50% of a comparable steel or concrete structure.
- 1 m³ CLT panels removes 0.8 tonnes CO2 from the atmosphere
- After adjusting for the carbon related to the transport (23 tonnes of emitted CO2) Crosfields has removed 435 tonnes of CO2
- Ultimately, the timber superstructure contains 137.439 tonnes of sequestered/ stored carbon
- As a guide, OP cement production emits approx 870kg CO2 per tonne and steel production emits approximately 1.75 tonnes CO2 per tonne.
CLT’s thermal qualities add to the overall performance of the building and its natural air permeability give it an almost Passivhaus level of performance, reducing the operational cost/ carbon of heating the school.
CLT walls were used directly as transfer elements, reducing the requirement for additional glulam or steel framing elements.
M&E was fully coordinated into the structure ahead of frame fabrication, further minimising on-site waste.
"Our teachers, support staff, parents and students havesimply been 'wowed' by the open, light, modern building that is now the heart of our new Senior School.”
CAROLINE PURDOM - Bursar, Crosfields School
CLIMATE RESILIENCE
Crosfields School has excellent sustainability credentials. Overall, there is a 25% improvement on Part L regulations and the building achieves an A-rated EPC, which is an outstanding achievement.
- The design maximises natural light and ventilation with clerestory windows and lightwells
- South-facing PVs provide renewable energy with a 12.58% reduction of carbon emissions, improving on the 10% Part L target
- High insulation, LED lighting with occupancy daylight sensing, heat recovery ventilation all assist in reducing the environmental impact
- A highlight is the Brise Soleil, which permits solar gain in the winter, but reduces overheating in the summer months.
The building has been assessed for climate change adaptability.
Although the site is classed as a very low risk for flooding, external floor levels have been designed to fall away from the building and its entrances, and a robust drainage strategy with permeable paving has been incorporated.
Changes in temperature have been assessed as low risk. However, the design has sought to future-proof the building allowing simple and cost effective adaptations to be made to address climate change.
COLLABORATIVE WORKING
A strong, one-team approach was adopted through clarity of vision from the client and excellent teamwork and communication.
Project partners were chosen for their openness to working collaboratively and to embracing the benefits of a digital workflow and offsite manufacture to deliver project excellence.
Design sign-off required us to work with multiple stakeholders including staff, governors, parents, pupils, planners, highways authorities and neighbours. An extremely high quality of communication, enhanced by the use of digital design techniques, meant that we achieved design approval in a timely and cost effective manner.
The BIM model was used to communicate design options very clearly, allowing quick decision making. Phasing options were agreed with all stakeholders to ensure the safest and most efficient site planning on a live site.
Early engagement with key subcontractors was key. Our team’s digital design skills and collaboration in the model with the CLT supplier led to robust coordination and cost certainty.
Regular clash detection workshops were undertaken to ensure architectural and MEP elements were fully coordinated with the prefabricated CLT superstructure prior to fabrication, leading to its seamless installation.
GETTING IT RIGHT
A key aim of the brief was for an exceptionally inclusive and welcoming building, in keeping with the school’s ethos.
The new entrance, cafe and double height performance space are striking as well as being welcoming, with the exposed timber and the play of light that comes deep into the building. The biophilic design brings proven wellbeing benefits in a school setting. This was particularly important to the school as the new building is home to its wellbeing.
The design is purposefully more ‘grown up’ than the rest of the school. Material choices are elegant and subtle and the interiors have a collegiate feel. These spaces lend themselves to being used for other functions for adult user groups outside of the day-to-day school requirements facilitating the school’s own work with community and external groups.
Through excellent communication and collaboration, the inclusive, welcoming approach was extended to the construction process.
During construction, Beard embedded an H&S-focused on-site culture with the workforce and visitors and achieved an exemplary H&S record with zero near misses and zero dangerous occurrences with the public interface.
The building process was a key learning opportunity for the pupils and staff as the MMC/ kit of parts approach made the construction process very visible and the completed building readable and understandable.
This was supported with regular visits including attending the topping out ceremony and learning about sustainability. The whole process of building was very clean, tidy and slick, enhancing the image of construction and inspiring an interest from the younger generation, staff and parents.
£4.7M
CONTRACT VALUE
62 WEEKS
CONTRACT DURATION
Customer
Crosfields School Trust
Architect
David Miller Architects
Quantity Surveyor
Madlins LLP
Form of Contract
JCT Design/Build 2016
The new building weaves around the existing site, its shape created both to protect trees and to wrap around and form a new open courtyard for pupils.
It provides a new front entrance, nine classrooms, staff area, library and wellbeing hub, along with a double height, flexible performance space and café that are the heart of the building and an amenity for the entire school. A covered walkway linking to the courtyard provides solar shading and creates a modern ‘cloister’ that adds to the collegiate feel that is in keeping with the distinct, ‘grown up’ identity of the new building. The first of two phases, the design allows for future additions, planned for when the senior school expands.
The project was delivered on time and on budget, despite losing three months on site due to the pandemic
