Carol Costello, architect and practice leader at Cullinan Studio, explains why they love working with timber and how they use the natural world to enrich people’s lives through the buildings they design.
Cullinan Studio is an architectural practice committed to restoring the connection between people and nature. Founded by RIBA Royal Gold Medalist Ted Cullinan in 1965, the cooperative business is employee-owned and has created award-winning projects for Kew and Edinburgh Botanic Gardens, Cambridge and Warwick Universities, the BFI, and many others.
The studio works across all sectors and scales, and believes that architecture is a social act, both in its creation and its impact on people and planet. In a world that is ever more urbanised and led by technology, Cullinan is dedicated to creating spaces that help people re-centre on what is important, reconnecting with each other and with the natural world.
Cullinan’s vision is a world where nature thrives and people’s lives are richer because of it, bringing us new opportunities to reimagine our cities and connect them with the natural world. We have a strong reputation for working creatively with timber and making it a part of sustainable, ethical building solutions.

Image ©Paul Raftery: RHS Garden Hyde Hall was designed as a space to inspire a nation to garden and grow
Timber is easy and quick to build with and has very low embodied carbon. We believe we need to use these kinds of materials if we’re going to tackle the climate challenge and meet our net-zero targets. There is overwhelming evidence that the loss of nature in our world is harming us and harming the planet. Planting more trees is so important, but so is using trees as a sustainable construction material. In terms of build, timber can give you a lot of advantages in areas like disruption, noise and speed on a building site.
Cullinan has signed up to the RIBA 2030 Climate Change Challenge, which means we measure embodied and operational carbon on all our projects, regardless of whether our client has included that as part of the brief.
Timber appears to offer a ready-made sustainable solution to many of the environmental questions being posed. Trees capture harmful CO₂ from the atmosphere and store it as carbon. When harvested for use in construction, wood can store carbon for a building’s entire lifecycle. When harvested from sustainable forests, more trees can be planted and the cycle of capturing CO₂ continues. As a result, increased adoption of timber in construction could deliver huge embodied and whole-life carbon savings on large projects.
It also seems increasingly clear that timber has a role to play in the modern methods of construction outlined in the Government’s Construction Playbook. Versatile and lightweight, timber is ideal for offsite construction, where whole systems can be built and delivered to the construction site for cost savings and increased build speed. Many parts of the timber industry are even ahead of the curve, with trussed rafters being a good example of how timber is a natural fit for offsite manufacturing.

Image ©Hufton+Crow: The National Automotive Innovation Centre has one of the largest glulam and CLT roofs in Europe
Can timber tackle complex projects?
We can do a lot more sophisticated things with timber as a building material. A few years ago we finished The National Automotive Innovation Centre at the University of Warwick. The building has one of the largest glulam and CLT roofs in Europe – a real tour de force of engineering. Jaguar, Land Rover and Tata motors realised that what their engineers were researching in the building is all about the future of mobility, and the need to be greener.
They see the sustainability of the architecture of this building as symbolic of their mission to create more sustainable transport and mobility.
Timber and wellbeing
Research has shown that using timber indoors, with the right coatings and treatments, improves indoor air quality and improves productivity in working environments. There is also evidence that timber used in the interior of buildings helps recovery in hospital situations, as we found in a project using CLT timber we carried out for Alder Hey Children’s hospital in Liverpool. Cullinan Studios was chosen as the winner of a RIBA competition to design new mental health buildings for the hospital, bringing physical and mental health departments for children and young adults together into a single space.
The two buildings’ names – Catkin Centre and Sunflower House – were chosen by children under the care of the hospital, who were keen to express how essential their existing garden and outside space has been for them while undergoing treatment. The two buildings were designed to ensure there is always a view of a garden or the adjacent park from wherever you are in the building.
Cloistered routes surround two courtyard buildings, where clusters of consulting rooms are gathered around an outdoor room and garden setting offering activities, views, daylight and fresh air.
Internally the building is made of timber, revealed and expressed throughout, and chosen for its warmth, smell and feel, and its environmental and wellbeing benefits. Places to wait, be alone or socialise are always enhanced by views of nature, daylight and natural ventilation, underpinned by the need to ensure patient dignity and discretion. www.cullinanstudio.com

Image ©PaulRaftery: The John Hope Gateway at the Royal Botanic Garden Edinburgh