CASE STUDY: Timber Square
Timber Square, located at 25 Lavington Street, is in the heart of Southwark. The proposed redevelopment scheme will deliver a mix of workspace and retail spaces, establishing a vibrant community whilst celebrating the heritage aspects of the site. Importantly, the scheme seeks to deliver a net zero carbon building, addressing both construction and operational impacts in line with the UKGBC Net Zero Carbon Buildings Framework.
Ambitious operational and embodied carbon emissions reduction targets will place 25 Lavington Street at the forefront of how new developments can respond to the climate emergency. These have been set in response to Landsec’s own net zero carbon commitments in face of the climate emergency: Landsec has pledged to be a net zero carbon business by 2030. To get there, Landsec has committed to reduce its carbon emissions by 70% by 2030 – which is in line with the Paris Agreement to keep the world within 1.5°C of global warming.
In 2016 Landsec became the first property company in the world to agree Approved Science Based Targets (SBTs); and are now the only real estate company in the UK with SBTs in line with a 1.5°C target. To date, Bennetts Associates are the only firm of architects worldwide, to have agreed Approved SBTs, which are also aligned with 1.5°C target. The Science-Based Targets initiative places organisations’ carbon reduction targets on a trajectory that is consistent with limiting the Paris Agreement.
Through a combination of the partial reuse of the existing structure of the East Building and the use of a hybrid steel/Cross Laminated Timber (CLT) structure, the embodied carbon emissions resulting from 25 Lavington Street will be significantly reduced compared to a typical London office building by about half. In addition, this project will be a pilot for the ‘Design for Performance’ initiative, which sets verifiable operational energy performance targets.
KEY SUSTAINABILITY OBJECTIVES/ OUTCOMES
- The scheme follows the UKGBC Advancing Net Zero programme and aims to be a net zero carbon building, in line with the framework definition published.
- Construction impacts are expected to be reduced by about 50% compared to a typical office, through the partial retention of the existing structure, the use of engineered timber as part of the structural design – an inherently low-carbon material and efficient design, incorporating off-site construction methods.
- An embodied and whole-life carbon assessment has been undertaken from early design stage and will be conducted throughout the project to ensure informed decision-making and drive embodied carbon emissions down.
- The energy strategy developed for the development does not rely on fossil fuel combustion on-site, and is targeting to achieve net zero carbon in operation by reducing energy demand and the supply of renewable electricity.
- The development follows the ‘Design for Performance’ (DfP) approach to deliver the expected energy performance once in operation.
- By assessing the embodied carbon emissions and selecting low embodied carbon products and construction materials, the project is targeting a carbon intensity of supply chain emissions of 550kgCO2/m2 GIA (465kgCO2/m2 with sequestration). The embodied carbon assessment will focus on emissions associated with manufacturing and construction stages, totalling up to the practical completion of the scheme.
- Reusing 70% of the original structure , around 25% of the new buildinh, saved 7,300tco2 compared to a completely new frame. The deconstruction of the previous building took longer than demolition and was more expensive, however, ~25% of structure will be built when construction commences which reduces construction time . The retention of the building also lead to a higher value floorplate compared to normal. (1a)*
- The existing steel frame windows are being refurbished and the existing light fitting (1b)*
- The previous raise access flooring has been shared onwards for reuse and they will aims to source reused raised access flooring when needed on the project. (1c)*
- There has been limited provisional office fit out designed on a 1.5 m planning grid allowing flexibility for the tenant fit out. (2b)*
- The Project ambition to maximise DfMA. Allowance for all major plant to be dismantled and removed. The reversible connections and modular, non-composite structural design means the building is designed so it can be disassembled. (2c & d)*
- There has been the requirement for standardisation and repetition across the building ie module assessmbly of unitised curtain walling. (3)*
- Maximising the use of low carbon, high recycled and regenerative materials like Cross-laminated timber. (5a)*
- They have specified concrete with high cement replacement and procured aluminium with a high recycled content. Use of composite sheet material made from recycled paper e. g Richlite for wall linings. Recycled RAF has approximately 20% the upfront carbon of new RAF. (5b)*
- Maximisation of DfMA. A project-specific Operational Waste Management Strategy, has been developed, making all necessary allowances to ensure that waste arisings can be accommodated under full occupancy. (5c)*- Construction impacts have been reduced through dry construction techniques, minimising wet trades on-site, minimisation of internal materials and a pr-demolition survey was undertaken to investigate maximisation of recycling any demolition and excavation material.
The project is hoping to change perceptions around reuse and what spec of materials is considered acceptable.
Health and wellbeing:
- The building had been designed to improved health and wellbeing through materials and access to green space offering value to the users and occupiers of the building.
NOTABLE APPROACHES AND SOLUTIONS
- At design stage the project measures:
- Carbon emissions from manufacturing and construction [assessed by a qualified consultant on the project].
- Carbon emissions expected in operations, through the Design for Performance framework [assessed by a qualified consultant on the project].
- The Proposed Development seeks to achieve net zero carbon in operation, through energy efficiency on-site, an all-electric energy strategy, and a green power purchase agreement. The project will procure 100% of renewable electricity during operation and construction, backed by Renewable Energy Guarantees of Origin.
- The development follows the ‘Design for Performance’ (DfP) approach, an emerging rating scheme aiming to drive down operational energy use within office buildings in the UK. As part of the DfP approach, an operational energy target is set at the project brief and an advanced energy simulation process conducted during design stages. Enhanced commissioning, aftercare and post-occupancy verification will ensure the building is built and operated to perform as intended.
- The operational energy target for the development is in line with Landsec’s ambition to reduce energy intensity by 40% across its portfolio by 2030, and aligns with the UKGBC energy performance targets for commercial offices aiming to achieve net zero carbon in operation.
- Advanced energy modelling will be used to test the design against a range of expected operational conditions to provide confidence that the performance target can be met. These modelled predictions will provide a reference point for value engineering considerations, commissioning, fine-tuning and in-use monitoring once the building is occupied.
- Once in operations, the building will report annual operational carbon impacts as a total (tCO2e) and in terms of intensity (kgCO2e/m2 GIA), in addition to annual operational energy use both as a total (kWh) and intensity (kWh/m2 GIA).
- Landsec procures 100% renewable electricity across its operations, which will be used to power the development, enabling a zero carbon operation.
- Embodied carbon reduction has been a key driving design consideration from project inception. Minimising embodied carbon has influenced both the architectural and structural design, as well as the building services as part of the overall energy strategy.
- Much of the East building existing structure on site will be retained, with a lightweight extension providing additional floors. This enables the existing asset to be renewed and brought up to modern efficiency standards whilst minimising the use of natural resources, exemplifying good sustainable growth.
- In addition to the retention of existing structure, the proposed development is targeting to reduce the embodied carbon of the proposed scheme through the use of Cross-Laminated Timber as key low-carbon construction material for the structure. Efficient design (incorporating modular and offsite construction methods) and the undertaking of a whole-life carbon assessment for the building to drive decision-making throughout stages further form part of the strategy to drive embodied carbon down.
- By assessing the embodied carbon emissions and selecting low embodied carbon products and construction materials, the project is targeting a carbon intensity of supply chain emissions of 500 kgCO2/m2 GIA for the East building and 600 kgCO2/m2 GIA for the West building. The embodied carbon assessment will focus on emissions associated with manufacturing and construction stages, totalling up to the practical completion of the scheme.
- The development will offset emissions associated with manufacturing and construction at the completion of the project. Landsec is currently investigating available offsetting mechanisms in order to identify the best-suited route for the project to pursue in due time. Offsetting frameworks considered include the Gold Standard, Clean Development Mechanism and Verified Carbon Standard.
- Reuse was incorporated at an early stage, which helped prevent challenges coming up later down the line; one challenge that remained was the required fire safety assessments as despite the building being made up of steel and concrete, it was challenging to guarantee the structural soundness.
- Further challenges were with the storage and the logistical side. Taking materials and products out of a building and keeping them to be reused in the new building was complicated. This meant sharing materials, like the raised access floor tiles, onwards with the hope of finding reuse items when needed in the build.
- One area which was not seen as a barrier was the upgrade to the masonry façade with replacing the windows and lining the fabric of the building. Going forward they would like to work with the building service strategy on retaining the existing asset.
* This project is included in the “How circular principles impact Carbon and Value” report.