At Elliott’s Field Phase II, Hammerson achieved two world firsts: the first ‘BREEAM Outstanding’ shopping park and the first ‘zero regulated carbon’ shopping park globally. These were key targets for the project team from the outset, achieved by incorporating passive design features and efficient building services to minimise energy demands, engagement with retailers on fit-outs and a major rooftop PV array to supply on-site electricity demand and offset emissions.
300 TONNES OF CO2 SAVED ANNUALLY FROM PV
£55,000 ESTIMATED ANNUAL ENERGY COST SAVINGS FOR RETAILERS
ZERO CARBON FOR ALL REGULATED EMISSIONS
SUPPORTING HAMMERSON’S NET POSITIVE TARGETS
Hammerson’s sustainability vision is to create retail destinations that deliver net positive impacts socially, economically and environmentally. As part of this, they have set a target to be Net Positive in carbon, resource use, water and socio-economic impacts by 2030.
Hammerson completed the first phase of Elliott’s Field shopping park in Rugby in 2015, achieving BREEAM Excellent. The second phase offered Hammerson the opportunity to push the boundaries further, contributing to the company’s commitment to become Net Positive and marking a significant milestone in its carbon objectives.
Hammerson set two key sustainability targets for the scheme at the outset:
- BREEAM Outstanding, the highest accreditation, achieved by less than 1% of new, non-domestic buildings, the highest retail score in the UK in 2017 and a world first for a shopping park.
- Zero carbon for all regulated energy usage, with energy efficiency measures reducing carbon emissions and on-site renewable sources offsetting the remaining emissions.
The team included Piper Whitlock as architect, Silcock Dawson as building services engineer and Hoare Lea as technical advisor and sustainability consultant.
Initiatives that contributed to zero carbon include:
- Passive design features to minimise energy demands, including high performance fabric and glazing, with optimised U-values: roof (0.16 W/m2K), walls (0.18 W/m2K), exposed floor (0.22 W/m2K), glazing (1.6 W/m2K).
- Efficient building services to further reduce energy use, including high efficiency LED lighting in all external areas, operated through both a time switch and daylight sensors.
- Agreements with retailers to fit out units with energy efficient systems. Limiting parameters in heads of terms included variable refrigerant flow (VRF) heating and cooling systems with a 4.5 minimum seasonal coefficient of performance (SCOP) and a 6.5 minimum cooling seasonal energy efficiency ratio (SEER), along with high efficiency mechanical ventilation heat recovery (MVHR) systems and limiting values for lighting loads.
- 775kW PV array on the rooftop to offset all remaining regulated emissions.
Materials and waste examples:
- 100% of aggregates from recycled sources, including foundations, pipe bedding and capping.
- 91% of materials for the shell achieved a BRE Green Guide to Specification rating of A or above.
- Changes made so a substantial majority of materials came from manufacturers with ISO 14001, BES 6001 or FSC certification (80% of entries in materials register), including high volume elements such as the structural steel frame, significant portions of the external walls, rainscreen cladding and louvres from FSC sources.
- Design variations to reduce embodied carbon, including replacing steel and aluminium with timber, acting as a carbon sink.
- Limited construction waste generated (1.5m3 per 100m2 of floor area, versus 1.6m3 BREEAM benchmark) and 98% of all waste diverted from landfill, achieving all BREEAM waste credits including innovation.
Additional sustainability initiatives implemented included:
- Rainwater harvesting for flushing toilets in the amenity block and Starbucks.
- 36 cycle spaces, along with cycle paths linking to local cycle routes.
- Amenity block with 12 lockers and two showers to encourage staff to cycle and run to work.
- Creation of a canal bankside nature area for wildlife, protecting wild orchids and providing priority habitats for wild butterfly species.
- Features to enhance ecological value, including over 22,000 new plants, bird boxes, bat boxes and log pile habitats for invertebrates.
- Educational programme with Warwickshire Wildlife Trust, to promote wildlife awareness on the River Swift running through Elliott’s Field, including interpretation boards and signed walking trails to the Oxford Canal.
- The project, inclusive of all sustainability initiatives outlined above, exceeded Hammerson’s internal hurdle return rates, meaning the scheme was both profitable and sustainable.
- The PV alone will save retailers an estimated £55,000 annually, with further savings expected from the enhanced energy efficient fit-outs.
- Savings will be verified by comparing design predictions with operational performance data, in conjunction with occupiers.
- High quality environment for shoppers inside and outdoors.
- Energy and CO2 savings for retailers through efficient design.
- Secure, cost effective access to electricity from the PV array for retailers.
- 300 tonnes of CO2 saved annually through the PV array.
- Contributing to Hammerson’s commitment to become Net Positive by 2030.
- Building relationships with occupiers from the outset and supporting their sustainability goals.
Challenges & Achievements
How to engage with retailers on sustainable fit-outs?
Retailer engagement early on was key because their fit-outs affect regulated energy demands. Hammerson already had experience partnering with Costa Coffee to deliver a zero carbon Eco Pod for regulated emissions in 2015 (more here). The key learnings from this project set the methodology for Elliott’s Field, which were:
- Open book collaboration with retailers from day one to understand their fit-out and regulated energy demands, to ensure that emissions could be offset by the roof mounted PV array.
- Store surveys to establish a likely energy benchmark and an example fit-out design, with plenty of flexibility, which the Elliott’s Field team took to retailers. Retailers often do not know what systems they will be installing in their units and are therefore cautious about lease agreements with specific energy performance requirements.
- Close liaison with retailers so that their designers incorporated the requirements, and technical support to retailers to refine fit-outs, e.g. selecting highly efficient equipment to reduce their regulated energy use.
- Incentive for retailers of direct supply of electricity from the PV, offering the dual benefit of reducing emissions and costs.
- Fit-out specifications agreed in heads of terms before leases were exchanged and then closely monitored on site.
ACHIEVING ZERO CARBON
How to predict regulated energy on a shopping park?
Regulated energy use at Elliott’s Field includes lighting, heating and air conditioning used by occupiers. Extensive modelling was carried out early on to predict regulated energy demand and identify opportunities to reduce it. This modelling accounted for a range of variables:
- Site location and weather, including sunlight, temperature and microclimate through sheltering and shading.
- Building layout, orientation, form, fabric, thermal mass and storage and building occupancy type.
- Daytime lighting strategy and likely ventilation strategies as part of occupier fit-outs.
- The potential impact of different future climate scenarios.
As a result of this modelling, passive design changes included improvements to fabric and optimised glazing. The PV array was carefully specified to offset remaining regulated emissions.
How to achieve BREEAM Outstanding on a shopping park?
To achieve BREEAM Outstanding, a score of at least 85% was needed. This was a key project target from the outset and the Development Manager and design team really took ownership of it. The sustainability consultant was integral to the team and involved in the design from early on. Once the few credits that could not be achieved were removed, there was very little margin, with the team aiming to achieve almost every credit available. Crafting the right design was crucial to this – optimising the shell for efficiency, for BREEAM credits and for lettability, with no compromise in appearance. The team changed the glazing to improve U-values and switched materials for ones with higher Green Guide ratings, e.g. cladding and roofing. They also introduced a range of initiatives, from rainwater harvesting on the amenity block, to the major PV array, which was a break from the norm for a shopping park. The process went smoothly because the team took ownership from the outset.