The Co-operative’ s 30,500m2 One Angel Square headquarters in Manchester has achieved the accolade of being one of the UK’s highest BREEAM-rated buildings with a BREEAM Outstanding score at interim (design) stage of 92.25 percent.
Sustainability is a cornerstone of the Co-operative Group’s principles. Since 2003 the retailer and financial services provider has reduced its greenhouse gas emissions by 38 percent. From 2007, 99 percent of the electricity supplied to the organisation has been from renewable sources. The group even has its own wind farms contributing to the energy needs of its stores and branches.
Challenges & Actions
3DReid divisional director Mike Hitchmough summarises the approach to sustainability at the Co-op, the UK’s highest rated BREEAM as “pragmatic innovation”.
It’s not about environmental ‘add-ons’ like wind turbines and solar panels. Sustainability here is a truly integrated part of the building and is also in line with the Co-op’s ethical corporate approach. It’s not about eco-bling,” he says.
The building has been designed to actually become more efficient as temperature rises. This resilience is achieved through an array of energy efficient features.
Fifty thousand litres of fresh air are sucked into the building every second via the three giant earth tubes poking up above the ground in the building’s landscaped forecourt. A stack system then distributes the air through the building via displacement vents, absorption into the thermal mass of the concrete and vertical extraction through the atrium.
As the air below the ground retains a fairly stable temperature of about 12°C throughout the year, the amount of energy required to temper it to comfortable levels is also minimised.
The building’s double skin facade also acts as a duvet that insulates the building in the winter and facilitates ventilation in the summer. The gap between the single-glazed outer skin and the weatherproofed inner skin is open at the bottom but vented by louvers at the top.
Solar control is also achieved by solar coating to the glass and the ingenious modulation of blade depths to the bronze mullions on the inner face of the outer skin. The depths are determined by the mullion’s position in relation to the building’s orientation, which essentially enables them to act like blinds that minimise solar glare when necessary.
That said, as Hitchmough wryly points out that
Manchester gets such little sunlight that the building is deliberately tilted to face southwards to grab as much energy as possible”. This is principally achieved through a heat recovery system in the atrium.
Other energy efficient measures include locally sourced materials (except for the bronze cladding), low-energy LED lighting in the atrium and a cogeneration CHP biofuel boiler running on waste cooking oil and rapeseed grown on the Co-op’s own farms. The waste heat from the boiler provides cooling via absorption chillers and chilled beams.
But Hitchmough is keen to stress that the building’s sustainability agenda has not just been delivered by features but by the attitude of the clients. On the external outer skin, they paid an additional £120,000 for a bronze anodised rather than powder-coated finish as this came with a lifetime guarantee that would reduce maintenance costs.
Furthermore, their insistence on such a high degree of internal flexibility will ensure the building’s adaptability for future uses, delivering a more sustainable long-term structure.
Lessons & Results
The building has been future-proofed against forecast 2050 temperatures – a predicted five percent increase in summer temperatures and a 30 percent reduction in winter temperatures.
Other key features include:
- Low energy LED lighting in the atrium
- Low energy IT equipment and systems
- Low water consumption appliances
- Greywater and rainwater recycling systems for toilet flushing and irrigation
- 10 high efficiency passenger lifts and three service lifts, with regenerative motors and destination controls.
One Angel Square is predicted to operate with 80 percent fewer carbon emissions and half the energy consumption of the Co-operative’s old head office, which is expected to save the group over £500,000 per annum. The company will be measuring performance. Peter Cookson, programme director of Co-operative Group, says:
We have built a big research project and we will be metering it to death to ensure we optimise the building.”
The new building will be used to drive more flexible ways of working both culturally and technically. Current working practices are often paper-based, using unnecessary space. By maximising digital storage, the building’s size has been optimised, minimising the use of construction materials. The planning module is based on one person per 8m2.
We’ve got rid of so much documentation. We would have needed two floors of the building to store it.”
Painting the exposed concrete balconies in the atrium white enabled the artificial lighting to be reduced from 550 to 300 lux, saving significant amounts of energy. More expensive bronze anodised facade components were used in place of a powder coated finish to reduce maintenance costs.
Building information modelling (BIM) was used on the project. Cookson explains:
We didn’t set out to use BIM, but we have by default.”