With a pioneering lean design, powered by 100% renewable grid electricity, this groundbreaking project will be the UK’s largest full timber frame, net zero carbon office building.

A large red brick building next to a busy main road in a sunny day

Key information


Piercy & Co


Global Holdings



Year of Completion




Xylo on Gray's Inn Road in Bloomsbury, London, will deliver a 95,000 sq ft modern office building with eight floors of bright, light workspace, a communal roof terrace and yoga deck, and five landscaped terraces with views of the city. Named with the Greek word for wood and constructed from CLT and glulam, Xylo will be the UK’s largest full timber office building. It will bring people together via a restaurant at ground level and a fully equipped active commuting hub.

In keeping with the culture of Clerkenwell, Farringdon and Hatton Garden as centres of innovation and creativity, a second 12,000 sq ft building on the site will provide six affordable apartments and an airy ground level affordable workspace to support the area’s entrepreneurs and creative industries.

Working for Global Holdings and alongside Piercy & Co, we are the MEP, Net Zero Carbon, Sustainability, BREEAM, and Acoustic Consultants for the project.

Innovative design

We have pioneered the building services engineering and energy performance and undertaken the whole lifecycle carbon modelling to surpass RIBA 2030 Climate Challenge and the GLA planning targets. This is being achieved through our net zero carbon service using the UKGBC Net Zero Carbon framework.

We are also leading the NABERS UK Design for Performance modelling in order to showcase the exemplar performance of the design and building once in use.

By pursuing innovative design and circular economy principles, construction methods and use of sustainable materials, this LETI Pioneer building will deliver a substantially reduced carbon footprint versus typical office buildings and is targeting a NABERS UK 5.5* energy rating.


renewable energy


targetting NABERS UK rating 5.5*


reduction in CO2 compared with a typical office building

Sustainability and wellbeing

The building’s operational energy efficiency and low lifetime carbon targets will be delivered via 100% renewable grid electricity, rooftop photovoltaic panels, an intelligent Building Management System, energy-efficient all-electric heating, hot water, and cooling systems, and demand-driven displacement ventilation to the office floors. The building’s occupiers can expect to reduce their occupational CO2 emissions by up to 82% compared to a typical office building.

The use of low-carbon materials and circular economy principles for the façade and interiors will exceed GLA and Camden policy targets for sustainability and energy efficiency, with the dry nature of the construction allowing for future deconstruction and re-use with minimal wastage.

The building also has a strong wellbeing ethos with landscaped terraces on most levels, a communal rooftop garden and yoga deck, and large windows to maximise daylight. The use of natural materials and extensive internal planting will help provide clean, highly oxygenated air, which will be continually assessed by air quality monitors, with the ventilation systems being designed in response to emerging Covid-19 ventilation guidelines.

“Achieving Net Zero Carbon requires a ‘whole building’ approach to design. We are thrilled to be part of a team that has pioneered lean design, carefully considered material selection, and explored the circular economy opportunities in order to reduce the embodied carbon emissions. We are committed to see the in-use performance realised and ultimately verified by others. We want to show that low energy design is not a concept but a reality in our lifetime.” 

Director, Mechanical Engineering Leader