Mole Architects deploys CLT for Design District studios – ADC

The Design District, London’s first permanent, purpose-built creative district, is conveniently located minutes’ walk from North Greenwich Station. Knight Dragon has developed a hub for creative businesses which it is hoped will act as a catalyst to developing a wider thriving community across the rest of Greenwich Peninsula. Affordable rates, with the option to rent a desk, a floor or an entire building, combined with great facilities like the Bureau, offering an affordable members’ club with flexible workspace, all allow companies to grow and adapt over time.

The current Allies and Morrison masterplan for the peninsula protects views of the O2 and restricts heights in Design District to four storeys, in marked contrast to the surrounding towers. HNNA’s plot layout for the area sets a strong, clear framework of streets, a central square and smaller piazzas that define movement through the site. The scale of the low-rise buildings and narrow streets creates a familiar urban scale that encourages a sense of community and interaction.

Viewed from the boundary of Design District, the sci-fi context of the surrounding tall towers and Millennium Dome dwarfs the Design District, making it feel lilliputian, but once you are navigating the narrow streets there is comfort in the familiar scale and interest in the engaging variety of buildings.

Eight different architects were brought together to design the 16 buildings. The brief set parameters defining the plot area, height, use and net internal area to gross internal area (79% efficiency), as well as cost per square foot (less than £300/sqft NIA). While HNNA coordinated the design development of all the plots, the individual architects were not allowed to share their ideas, to ensure they felt free to innovate around the brief individually.

The brief, devised over seven years ago, did not require performance beyond building regulations and planning sustainability requirements. The discussion on sustainability has moved on in the intervening years, with The London Energy Transformation Initiative (LETI) publishing its Climate Emergency Design Guide, as well as the ESG requirements of investors and major developers making commitments to absolute zero. If the brief for the site were set today, embodied carbon targets, requirements to allow for adaptability, recycled material content, demountability and biodiversity would also need to be considered.

I had the pleasure of working with Meredith Bowles over 20 years ago. His commitment to sustainable design was as uncompromising then as it is now, and the same core values and rigour underpin the design of the practice’s two buildings at the Design District.

Mole Architects referenced the area’s history as a gas research and storage centre to give context to the design concept. The Ziggurat, so named because the floor plates step in on each level, is clad in recyclable Corten panels angled at 45 degrees, hinting at the spirally guided mechanisms of the old gasholders. The Rhomboid, named after its floor plan shape, is clad in iridescent aluminium serrated sheets, evoking a flickering gas flame. A tenant named it the ‘Mermaid Pleat’ building, which poetically evokes the luminescence of the façade.

While the buildings’ external appearances differ, they are both borne out of the same environmentally and socially sustainable ethos. The two buildings are the only ones in the Design District to have structural mass timber frames and cores. Ziggurat is designed around a glued laminated (glulam) timber frame with structural cross-laminated timber (CLT) floors, stairs and lift shaft, with structural insulated panel (SIP) walls. Both buildings achieved a BREEAM Excellent rating.

The Rhomboid, is constructed from cross-laminated timber (CLT). The CLT floors are supported by a central timber glulam beam running diagonally across the plan, supported on two timber glulam columns. In both buildings the solid timber floor slabs are exposed on the soffit, with a raised floor distributing services. The timber construction has resulted in an embodied carbon saving of 57% kgC02/m2 for Ziggurat, and 48% saving of kgC02/m2 for the construction of Rhomboid compared to an equivalent concrete structure using A1-A5 (cradle to practical completion) reporting.

While the cladding on each buildings appears very different, they are both lightweight. This minimises the loads on the structure and foundations, and consequently reduces the size of sub and super structure, making the building more materially efficient. The walls are lined with innovative phase change wall boards designed to provide lightweight thermal mass that absorbs, stores and releases latent heat from within the building as well as stabilising the moisture content within the room.

The top floors of both buildings are flooded with natural light. The Ziggurat employs a sawtooth section to bring north light into the space, while the butterfly roof on the Rhomboid building incorporates two triangular rooflights at the high points. Both roofs are constructed from an exposed joist structure with a ply deck. This is a materially efficient solution where the structural strength of CLT is not needed for roof loadings, and it also has the advantage of making any damage to the waterproofing easier to identify.

The openable roof lights form part of an overarching natural daylighting and ventilation strategy which includes openable wall vents or windows, manually operated external blinds to the west and south elevations, as well as vertical fixed solar shades on the east of The Ziggurat. The glass vertical fins on the Rhomboid not only provide solar shading but also refract the light, with the colour dependent on the angle of the sun at a given time of day and year. Not only do the shading measures reduce the electricity demand for lighting and cooling and give the tenants agency over their own environment, they also work with the sunlight, casting an ever-changing playful display of colour.

The floor plates are not deep and were designed as open plan, however as the brief evolved and the future tenants’ requirements became clearer, there was a demand for smaller units. The spaces have subsequently been subdivided and while this can have an impact on the natural ventilation strategy, it demonstrates the plan is adaptable to the tenants’ changing needs and should increase the longevity and lifespan of the buildings.

I met some of the newly installed creatives in both buildings, many of whom had moved south of the river from warehouse workspaces in Hackney due to rent increases or redevelopment. It was clear from them that the quality of the space and light, as well as the biophilic benefits of the timber structure, institutes a relaxed and productive working environment.

We know the climate is changing; it is in crisis, and this demands a fundamental change in the way we think about how we design. There are a handful of architects who are meaningfully addressing the challenges of the climate emergency and who are at the same time creating inspiring spaces for people to enjoy. Mole Architects’ tectonic approach combines both rigour and rationality with a sensitivity to the needs of the end user to make buildings that minimise their impact on the environment and have an indisputable benefit to the people using them.