Holbein Gardens

Redevelopment and one storey extension of a 1980s office building off Sloane Square, creating a 25,000 sq ft modern workplace planned to align with the UKGBC’s Net Zero Carbon Buildings: A Framework Definition.

Climate change:

• Current whole life carbon assessments show the upfront embodied carbon is on track to achieve 300kg/co2e/m2which is less than that of the LETI 2030 upfront carbon target (350kgCO2/m2). This has been largely achieved through retaining the existing structure and façade, whilst trialling new low-embodied carbon and circular innovations.
• Operational use: effective lighting and mechanical equipment, all-electric power supply with 100% renewable energy procurement. On-site renewable energy produced from solar PVs, blue roofs and sustainable urban drainage systems.

Resource use:

• There has been a 29% embodied carbon saving through retaining the brick façade, equivalent to 59 tonnes of carbon equivalent emissions (kgCO2e). (1b)*
• Specifying 34% steel from reused resources has accounted for a 60tCO2e saving in upfront carbon (in comparison to OneClickLCA’s generic Structural Steel profile (20% recycled content)) approximately a 6% saving in upfront carbon impact. However, this did have an increased cost due to extraction from the old site, transportation and testing for reuse. (1b) *
• Other reused materials include York stone pavers for ground floor entrances which have a 3.2tCO2e saving in upfront carbon (A1-A5). (1b)* 99.95% of strip out waste diverted from landfill and traded on the re-use marketplace Globechain, the timber removed from the building has been donated to St Albans wood recycling charity, and some carpet tiles have been shared onwards. (1c)*
• The space has been designed to be flexible with the CLT extensions allowing the floorplates to be adapted in the future. The MEPH plant has planned preventative maintenance to extend to lifespan of the plan and exposed finishes elsewhere in the building allow for easy maintenance and flexibility to zone future spaces in different configurations. (2b)*
• Elements of the building have been designed to be disassembled at end of life through mechanical fixings and lime mortar which can be cleaned off the bricks. (2d)*
• Although the use of standardised products has been limited through reuse of the building prefabricated kitchen unites and MEPH kit of parts have been standardised to allow modular building and removal. (3)*
• Materials with high recycled content including CEMFREE concrete and Cross laminated timber have been used to lower carbon although both may have a cost uplift. (5b)*

Nature and biodiversity:

• Increase in biodiversity with 11% of the building’s GIA is to be green space that supports the Wild West End initiative and UGF of 0.26.
• Using the Defra Metric a Biodiversity Net Gain on site of 200% increase has been achieved.

Health and Wellbeing:

• Mixed-mode ventilation with windows openable. Circadian lighting reflects natural daylight cycle.
• 70 bicycle spaces.

Socio-economic:

• Donating surplus materials: carpet tiles + timber doors / panels donated – Globechain + Community Wood Recycling.
• Surplus materials are being distributed locally.
• Extensive ground floor vegetation and green walls – improved local amenities and air quality.