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Sustainability lessons from building the Co-Op’s head office

Bam Construct was tasked with achieving extremely high levels of sustainability at the new Co-Operative Group’s head office. The project team achieved their targets and learnt some interesting lessons on the way.

Scheme The Co-operative Group’s Head Office, 1 Angel Square, Manchester

Client The Co-operative Group

Main contractor Bam Construct UK

Contract value £105m

Architect: 3D Reid

Structural and M&E engineer: Buro Happold

Project manager/QS Gardiner & Theobald

The Co-operative Group invested just over £100m in its new head office in Manchester, the first phase of the redevelopment and regeneration of its 20-acre site in the city.

The wider development, known as NOMA, is located at the city’s Northern Gateway, and the new building is designed to anchor the scheme.

The entire development is intended to be responsible, combining commercial goals with the values that underpin The Co-operative Group: “Profit for a purpose, putting people and communities first.”

The aim was to create one of the most sustainable commercial buildings in Europe. Architects 3D Reid, with structural and M&E engineering consultants Buro Happold, were brought on board to make sure the design achieved a BREEAM Outstanding rating.

Contractual green targets

Bam Construct was appointed as the main contractor for the head office at design stage C in 2009, with senior M&E manager Dennis Whitely describing the brief as “extremely demanding”.

“This is not a normal building and there’s nothing really to compare it to,” he says.

In addition to the BREEAM target, the building also had to achieve an A rating on its Display Energy Certificate. The ratings requirements were written into the contract by the client.

“Everybody – the designers, architects, engineers, client, end-users, us – had access to each other to make sure that we were working together”

Dennis Whitely, Bam Construct

“These initial contract parameters focused everybody’s minds,” Mr Whitely says. “The capital cost of what needs to be done to achieve the ratings pales into insignificance when you have a contractual obligation to achieve them.”

The team employed a dedicated BREEAM consultant, Scott Hughes Design, from the very beginning of the project.

“The adviser understood the system completely and, more importantly, the pitfalls of it,” Mr Whitely says.

World-beating ambitions

An interim design-stage assessment gave the building an Outstanding score of 85.36 per cent, one of only 40 buildings worldwide at the time to achieve the rating. The team is targeting a “best-case” final post-construction score of 95.2 per cent which, if achieved, would make it the highest-scoring building ever recorded.

The 15-storey building opened in autumn 2012 and has become the home of more than 3,000 Co-operative Group employees working across the company’s retailing and financial services businesses.

Early engagement was vital to delivering a complex building with such high environmental standards, Mr Whitely explains.

“This project was managed to the extreme, from top to bottom,” he says. “The client allowed us direct access to their team so that we could better understand what they wanted and needed from the design, as well as the company’s culture and approach.

“We focused on specifics. Everybody – the designers, architects, engineers, client, end-users, us – had access to each other to make sure that we were working together.”

Changing the plan early on

An early design change came with the building’s façade. Initially, the design planned for a twin-skin glass façade that would surround the building, with the external layer acting as an exhaust route for the building’s air supply. The project team were concerned about potential condensation build-up on the inner side of the glass as air was expelled.

The plan was changed so that the façade would act as a thermal jacket for the building instead. Louvres at the top of the building allow warm air trapped between the two skins to escape during summer, while they will close in winter to form an insulated blanket.

“The Co-op actually changed its farming practices to meet the business case for this building”

Dennis Whitely, Bam Construct

The energy-saving potential of the system had not been proven in practice, which made it a challenge to implement, Mr Whitely explains. “The design and detailing had already progressed quite far when the change was made, but we overcame this with extensive building information modelling design and remodelling.”

The building was never fully modelled in 3D using BIM, but it was used heavily throughout the design and planning stages, ironing out most problems before work commenced.

“We used it a lot due to the large number of pinch points and varying tolerances,” Mr Whitely says.

Array of sustainable features

The building included an extensive range of sustainability measures to achieve the required energy ratings.

One of the biggest features is the onsite combined heat and power plant, with two 397 kW units each providing 400 kW of energy.

Usually run on biodiesel, Bam Construct proposed using plant oil as fuel instead. All of the oil used is extracted from 70,000 acres of oilseed rape grown on rotation by the Co-operative Group.

“The Co-op actually changed its farming practices to meet the business case for this building,” Mr Whitely says. “Fallow land is now used to grow the crop needed for the plant oil, whereas it was empty before.”

There is capacity to store 60,000 litres of plant oil on site, and the plant provides the majority of the energy needed for the building.

The system even secures payback for the client through the Renewables Obligation by exporting excess energy back to the grid. Any waste heat is sent through an absorption chiller, which is then used for cooling.

“There were some initial niggles with the CHP as not many systems use plant oil, but the system was tweaked and tuned and is working properly now,” Mr Whitely says.

Other measures used include earth tubes that temper fresh air into the building, chilled beams and exposed concrete coffers, extensive free cooling (2,600 kW heat rejection and 1,100 kW free cooling), intelligent destination lift control with regenerative lift motors, the use of natural refrigerants throughout the building in place of hydrofluorocarbons, and harvesting of both greywater and rainwater.

“None of these technologies are particularly new, but the biggest challenge came in integrating them all together,” Mr Whitely says. “Making sure all the elements worked with each other and the structure was difficult, and the whole team had to come together to achieve this.”

The results of combining technologies

The combination of all this technology meant the building was awarded 15 out of 15 credits in the Reduction of CO2 Emissions section of the BREEAM ratings.

Two additional innovation credits were also awarded thanks to the negative energy systems that feed back to the grid, giving a total score of 17 out of 15 on that section.

“This took a lot of getting used to for the staff, but Co-op was really keen to implement a cultural shift among its employees”

Dennis Whitely, Bam Construct

As well as BREEAM Outstanding, the building achieved the DEC A rating and an Energy Performance Certificate rating of A+. It is the first building to achieve all three accreditations to this level.

The building’s energy consumption will not exceed 150 kWh/sq m, with an 80 per cent reduction in carbon emissions and a 50 per cent reduction in energy consumption compared with the Co-operative’s current head office.

Water consumption is also low and will be less than 1.5 cu m per person per year thanks to the use of rainwater and greywater harvesting, as well as low water-consuming fittings.

“This took a lot of getting used to for the staff, but Co-op was really keen to implement a cultural shift among its employees,” Mr Whitely says (see box).

The benefits of BIM

Cost savings will only become clear after a 12-month post-occupancy review, but Mr Whitely points to several lessons Bam Construct has learned from working on the project.

“You obviously learn lessons with any building that you do, but this one is very different from others,” he explains.

“I think it showed the need to invest even more in BIM and 3D modelling so that we can show the end-user exactly what they’re going to get. We did it for detailed parts of this building, but not the whole thing.”

The difficulty of achieving numerous stringent environmental ratings also provided an important lesson.

“It was actually a problem to begin with, as there were no base assessments from other buildings on which to base projections for this one – it was unique,” Mr Whitely says. “We had to come up with our own model from scratch.

“Extremely close liaison between all the parties involved was needed to get through this and hit the targets we wanted to. The three main parameters of the contract were the BREEAM rating, the DEC rating and the 140 kW/annum energy consumption requirement. We can safely say that all of those parameters have been met.”

Changing the Co-operative culture

In addition to educating and encouraging staff to use less water, the Co-operative Group has been keen to change the wider culture of its employees, shifting attitudes towards saving as much energy as possible.

This is reflected in the new flexible working pattern, with around 3,500 staff sharing 2,800 desks at an occupational level of 83 per cent. The volume of paper used has been reduced as a result and IT measures have been reviewed and altered to save energy. Large volumes of documents have been scanned, digitised and made available online.

Staff are even being encouraged to travel to work in greener way. Parking provision at the building has been reduced from the previous office, with no general car parking spaces to try to promote the use of public transport. An electric car charging zone has also been installed.

The changes resulted in a 7 per cent increase in staff walking and cycling to the site, with single-occupancy car journeys reduced by 10 per cent during the duration of the project.

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