Operational energy performance

The key sustainability target for Pall Mall was that it is net zero in operation with low energy consumption. The aim was for all electricity supplied to the building to be derived from renewable sources, and intelligent building management technology will also be incorporated throughout to ensure energy use is optimised.

A switch from gas heating to hybrid variable refrigerant flow (HVRF), with an air source heat pump (ASHP) serving domestic hot water and air handling unit (AHU) coils will dramatically reduce the overall carbon emissions and set the building on a trajectory for zero carbon as the grid emissions reduce. Note that achieving the ‘Paris Proof Targets’ as set out in UKGBC guidance was not possible due to the existing nature of the building and the listed status, as certain elements of the fabric were required to remain, however, a 74% EUI reduction is predicted. A focus on air tightness and façade replacement, within the constraints of the listed building status provided a significant energy consumption improvement.

Resource use and circular economy

The fit-out uses circular economy approaches by utilising recycled and reclaimed furniture and materials for timber partitions and reclaimed raised access floors. Through retaining the existing structure, Bruntwood has avoided the need to rebuild which is estimated to have resulted in approximately 7,900 tonnes of additional carbon emitted – equivalent to around 16,000 flights from London to New York.

Climate change adaptation

The new façade and glazing system has been designed to limit the solar gain to the building and thus limit the energy required to cool it. At the same time, it will allow the building to respond to increasing external temperatures over time.

Health, well-being and social value

The site contained an existing external area of public realm that was under-utilised and a target for anti-social behaviour, therefore the space was redesigned to create a vibrant amenity area and linked to the retail space within the building.

Climate change mitigation

The carbon assessments achieved the below figures at stage 4 design:

• Upfront Carbon (A1 A5) – 393 kg CO2e/m2,
• Embodied Carbon ( A1-A5, B1–B5, C1-C4) 840 kg CO2e/m2
• Operational Energy – 99.8 kWh/m2 per annum

This was based on most of the structure and façade being retained, with window replacements and the addition of an upper floor. The most impactful measures included; switching from gas boilers to ASHP, improving the efficiency of the AHUs (Air Handling Units), implementing demand-led ventilation, and refining the fabric performance.

As part of the Design for Performance process, it was necessary to model ‘off-axis scenarios’. These are iterations of the energy model that consider potential variations from the baseline design, such as future increased summer temperatures, failure or mis-operation of key systems, changes to occupancy, or increased air permeability.

The modelled operational energy performance of the building – which was completed in line with NABERS Design for Performance standards – was sufficient to achieve a NABERS 5* rating at the design stage, including the necessary margin.

Health, well-being and social value

Targeting £70 – £111million in social value over the lifecycle of the development through:

• Jobs: promoting local skills and employment
• Growth: supporting growth of responsible regional business
• Social: healthier, safer, and more resilient communities

Resource use and circular economy

To minimise the embodied carbon impact, the structure was maintained and, instead, the building underwent an exterior refurbishment with solar PV and solar shading installed.

Operational energy performance

The core plant and all heating and ventilation equipment were replaced. Alongside this, technologically integrated variable air flow valves were included which enabled automated air quality management on a localised basis. The lighting was upgraded to new, highly-efficient LED systems.

To support the ongoing running of the building, a new building management system (BMS) was installed, integrating a smart building server, sensors, access and visitor management systems. Furthermore, a building app Coalhouse.life was introduced to facilitate interaction between the smart technology, building amenity and the building occupants.

Health, well-being and social value

Had the required level of investment not been committed, the asset was at risk of becoming a stranded asset, but it now makes a strong and positive impact on the users and the streetscape along a key route through Cardiff city centre, thereby contributing to broader social value.

Resource use and circular economy

To establish the best retrofit strategy the team undertook a whole life carbon options appraisals considering a number of scenarios from a light retrofit to a complete demolition and rebuild. This analysis shaped the project brief, ultimately resulting in the deep retrofit and repositioning of the asset as opposed to more whole life carbon intensive outcomes.

A deep retrofit enables the building to take a major step toward net zero carbon in operation whilst retaining the existing frame & foundations, making significant savings in embodied carbon emissions as a result. The whole life carbon options appraisal was an effective tool is providing comparative data and creating meaningful discussions on the benefits of frame retention.

Operational energy performance

Operational energy performance savings have been identified via NABERS Design for Performance modelling and EPC modelling to define a performance-based design that will also deliver an high-performing Regulatory outcome. The building is targeting a NABERS UK 5-star rating & EPC A.

Notable energy & carbon savings have been enabled via:

• Early engagement and provision of comparative whole life carbon data at an early stage.
• Retention of the existing frame and foundations.
• Optimising core location and arrangement, riser provision and naturally lit office arrangement.
• An optimised façade design balancing daylight, thermal performance and solar control
• Systems control and build automation eliminating unnecessary energy consumption in the first instance
• Good management practices and the provision of systems that enable insight and interrogation of building performance.

From a cost perspective, the major refurbishment of Havelock came in toward the top end of the benchmark range for re-purposing/refurbishment schemes in Manchester in late 2021. This is reflective of the level of ambition and extent of the works. Notwithstanding this, it is estimated that the contract sum was approximately 25-35% less than the equivalent cost for a new build Grade A office in Manchester (late 2021).

Operational energy performance

The building will be fully electrified, and no fossil fuel use is proposed: it will be mechanically ventilated with heat recovery in place to reduce energy demand. The heating and cooling demands of the building will be met by highly-efficient modular Variable Refrigerant Flow (VRF) systems installed in accordance with BCO guidance for zoning.

A 57% reduction in EUI is anticipated to be achieved through a deep retrofit of the building. This is, in part, due to a proportion of the existing fabric being removed and replaced with a new system which will increase the air tightness and thermal performance of the building. The retained façade will also be insulated, and the glazing replaced to ensure the thermal performance is improved.

Resource use and circular economy

Through careful planning, 75% of the existing structure (by volume) will be retained and only 25% will be demolished to make way for a new extension structure. The existing structure comprises 55% of the overall proposed building structure volume.

Health, well-being and social value

An important driver for the retrofit project is improving the quality of the space to attract new tenants and improve user well-being. Roof terraces with extensive planting are proposed on levels 5-9, providing valuable amenity outdoor space for the building users, promoting their wellbeing and connection with nature. The scheme will also include two plant enclosures at roof level which will be covered in full height green walls.

Climate change adaptation

Blue roof attenuation will be adopted on the roof terraces, reducing the overall site discharge rate in excess of 60% from the existing flow rate. The river wall is also designed with consideration for rising sea and flood levels. The wall will have the provision for extension, should the need arise in the future.

Water efficiency

A combined rainwater and greywater reclamation system will be provided to capture rainwater from the building’s terraces along with greywater from the showers. This will be treated on-site for reuse to reduce the amount of fresh potable water the building needs. The treated water will be used to irrigate the terraces planting, and for WC flushes.

Biodiversity

Biodiversity is promoted through the wide range of planting proposed, ranging from sedum and wildflower green roof blankets to lush herbaceous planting. Swallow terraces and swift boxes will be integrated within the new façade areas to increase local habitat for these birds. New trees and planting will be added to the site as part of the new public realm design at ground level. The development will achieve an overall Urban Greening Factor of 0.3.

Operational energy performance

Light Retrofit – The overall retrofit strategy was to initially carry out a light retrofit of the office spaces to replace the CatA fit-out with an efficient solution and converting from the existing VAV system to minimum fresh air and fan coil units. This was combined with some significant structural interventions in areas of the building where there is a change of use.

Deep Retrofit – Once the office spaces have been retrofitted, a deep retrofit of the central plant was carried out, replacing gas-fired boilers and air-cooled chillers with air source heat pumps.

Health, well-being and social value

An important driver for the retrofit project was improving the quality of the space to attract new tenants and to increase the lettable area. This was achieved by increasing the perimeter floor-to-ceiling heights by 500mm and undertaking structural interventions to create a better-connected floor plate. Roof terraces were added with the necessary slab strengthening. Mezzanines in double-height spaces were also added and an under-used loading bay and basement car parking were converted into office spaces. Where planning permission was required due to building extension, BREEAM certification was achieved.

Operational energy performance

The software identified inefficiencies such as the plant running times being inconsistent with occupant hours, meaning vacant floors often had air conditioning units running. Flawed air recirculation strategies were also in place that did not fully utilise the available heat recovery/energy conserving functionality, due to ineffective Building Management System (BMS) control.

After the completion of the initial actions to address these issues, the electricity consumption in November/December reduced from a baseline of approximately 4800 kWh/day to 3800kWh/day (-20%), equating to cost savings of more than £100,000. Virtual meters also estimate a reduction of around 25% in gas consumption from boilers. The platform was key in facilitating collaboration between tenants, the landlord and the operations/facilities management (FM) team.

Operational energy performance

The four most significant energy savings that had relatively little impact on the use of the building were – in descending order – ASHPs, HVAC upgrades, lighting improvements, and mixed mode operation. More noticeable changes, such as tenant IT (mostly cloud servers) and behaviour (temperature set points, dress codes and remote working approach) are ones over which the landlord has limited operational control, but which do still have a marked influence.

Demand Control Ventilation: New variable air volume (VAV) terminal units will provide demand-based control of the ventilation system. The VAV units will extend from the reused main riser ductwork and be controlled via CO₂ sensors used to measure the equivalent level of occupancy. This will significantly reduce the amount of ventilation air required during periods of lighter occupation.

Partial Mixed Mode Operation: The existing smoke vents within the perimeter facades will be re-tasked to provide natural ventilation to the office floors. Actuators will be refurbished or replaced as required and interface units provided to allow connection and control to the building management control system. This will allow passive ventilation to the perimeter zones during the shoulder period (spring and autumn). When either too cold or too warm the whole building will revert to sealed operation.

Resource use and circular economy

The ethos is to minimise the embodied carbon associated with the project via the retention and refurbishment of as much of the existing building as feasible, including the façade and centralised MEP. The existing air handling plant and secondary pump sets will be comprehensively refurbished. Pipework and ductwork installations, main electrical infrastructure and distribution are to be retained (following testing).

Health, well-being and social value

Common spaces are to be revitalised, roof terraces updated, with planting and bio-diversity increased. Demand controlled ventilation will lead to improved air quality while also reducing energy consumption.

Embodied Carbon

The superstructure of the Martlesham project uses entirely natural regenerative materials including LVL roof beams, wood-fibre insulation, timber joists, hemp fiber insulation bats, and vertical Douglas Fir rainscreen cladding. Additionally, the building’s estimated Life Cycle Assessment (A1-A5) is only 219kg Ce/m² with biogenic carbon estimated at 1.36 tCe/m² resulting in a net -1.139 tCe/m². The wall cassettes used in the building require no primary structure up to 3 stories, but the system allows for the later integration of an LVL frame for vertical extension up to 8 stories.

Resource Use and Circular Economy

Natural Building Systems manufactured the cassettes used in the Martlesham project with Design for Deconstruction and Design for Adaptation principles in mind. Their standardized building system allows for rapid site assembly using timber spline pegs. This assembly method allows for the potential to re-configure and re-use individual cassettes and components during the service life of the building, and ultimately disassemble and re-use the entire building elsewhere. The building’s superstructure also allows for disassembly and adaptation by using pre-manufactured components, while the substructure uses compacted hardcore recovered from the site area. Off-site production using digital design and manufacturing tools optimizes material efficiency and reduces waste.

Operational Energy Performance

The HempSil bio-composite and hemp-fibre insulation used in the Martlesham project allow high levels of thermal and vapour buffering, reducing the risk of summer overheating and improving indoor air quality. The building’s estimated Energy Use Intensity (EUI) is only 60 kWh/m² per year.

Resource use and the circular economy

JLL took a circular economy approach to design and specification, adopting whole-life-thinking to minimise waste at end of life as the project has been designed for a 5-year lease. This involved approaching the design according to the following circular economy hierarchy:

Avoid using materials in the first place.

This included adopting an open floor plan to build in flexibility as well as reduce the amount of M&E required and the associated embodied carbon. Less cellular spaces reduce the amount of lighting controls and fan coil units required. Open, collaborative space also increases the flexibility of the furniture you need to procure as well. The project also has less workstations than the previous office, which is impactful on embodied carbon as workstations typically have steel frames. This is in part due to reduced office area but also the de-prioritisation of workstations to encourage people to use different spaces for different tasks. The design concept is that people come to the office to collaborate, not just work at a desk, so greater variety has been provided including hybrid space, private and semi-private meeting spaces to complement the permanent workstations. Further material abatement was achieved through avoiding the use of a suspended ceiling.

Where materials are required, prioritise reuse.

The project used 1,244 refurbished or reused furniture items equating to 79% of furniture installation. 1,250 items were also donated to Business2Schools ensuring all furniture was reused from the previous office clearance.

Where there is no reused option available, prioritise the procurement of low impact materials.

The project involved a variety of alternative materials such as Durat worktops from 100% recyclable post-industrial plastic waste, smile plastic use on worktops, acoustic soffit spray from recycled natural materials, Buxkin made from 60% recycled leather waste and other natural materials.

Ensure the materials used can be reused in the future.

Strategies were employed to achieve this including using reversible fixings and modular design using standard sized building components. The feature lighting not forming part of Cat A can be reused, meeting spaces for up to four people were delivered as furniture solutions, which are demountable and already identified for reuse on other JLL fit outs. JLL prioritises reusing materials at end-of-life in its own office fit outs, but if that is not possible reuse in situ or placement on the secondary market is preferred.

Climate mitigation

Operational energy

Energy efficiency is prioritised throughout the design, with the office currently achieving an Energy Use Intensity of 75 kWhe/m2/year, and an energy reduction of 40% per sqm compared to JLL’s previous Canary Wharf office. JLL is seeking to bring this down to 70 kWhe/m2/year to be in line with UKGBC’s 2020-2025 energy performance target for offices (tenant only).

To achieve this, JLL are optimising the ventilation system, implementing floor shutdown on low occupancy days, adjusting PIR sensors on lighting and raising set points on comms rooms to reduce cooling loads. JLL has also reduced the run time on the Building Management System (BMS), especially on low occupancy days, primarily addressing fan coil unit load but also delivering energy savings on the base build services. It is worth noting, under NABERS energy boundaries that electrical load for fan coil units sits with the landlord, even though it is metered on the tenant distribution boards. If JLL were to allocate this energy consumption back to the landlord they would already be meeting the 70 kWhe/m2/year target.

The project also involved a downsizing from their previous office, which reduced the overall energy consumption and delivered a reduction in energy use intensity. The installation of circuit level monitoring will enable to JLL to identify other energy saving opportunities and quantify the impact of operational changes.

Embodied Carbon

The circular economy strategy on JLL’s 20 Water St office fit out led to a 42% reduction in embodied carbon compared to JLL’s notional baseline. The total upfront embodied carbon including all the Category A fit out (except the raised access floor) was 186 kgCO2/m2. The embodied carbon assessment adopted RICS Whole Life Carbon assessment from stages A1 to A5.

The majority of the upfront embodied carbon reductions came from furniture, fixtures and fittings (FFE), with a 52% reduction against baseline achieved. Some carbon savings were achieved in mechanical and electrical (M&E) services, with a 10% reduction achieved on this package.  To meet JLL’s target of halving the carbon intensity of its fit outs additional strategies to reduce embodied carbon on M&E package will need to be identified.

Renewable energy procurement

The office is fully electric fit-out, including the on-site kitchen and catering services, with 100% Renewable Energy supply from Smartest Energy. JLL’s energy procurement is independently verified as natural source renewables, REGO backed and audited by the Carbon Trust. JLL are seeking to identify new opportunities which will deliver additionality into the UK grid. For corporate occupiers making longer term energy procurement decisions it represents a change to the existing approach, with many organisations simply having insufficient demand to enter the PPA market. JLL is active with UKGBC as customers collectively applying pressure on suppliers to innovate and improve the offerings available to increase the renewable generation being built.

Inclusive design, active workplace design, wellbeing and social value  

The project set sustainability targets beyond carbon, certification, and circularity. 20 Water St was the first application of JLL’s Inclusive Workplace standard meeting the highest criteria across all 20 concepts of JLL UK Inclusive workplace standard. Rooms were specified to support parenting needs, address neurodiversity and support multi-faith groups.

A variety of different work settings encourage movement around the floorplate, height adjustable workstations, the central location of key amenity and wellbeing spaces for games, yoga and guided meditation encourage JLL colleagues to thrive within the office.

Targets were set for indoor air quality with maximum levels for CO2 and volatile organic compounds, with data from 44 indoor air quality sensors visualised to communicate with JLL colleagues the quality of air across the floorplate. Two green walls and over 1,200 plants help improve air quality and provide a connection to nature.