BREEAM award winning building predicted to produce 80% lower carbon emissions

Thousands of Building4change.com readers voted to select the Your BREEAM Award winner from the top three BREEAM scoring shortlisted buildings in eight award categories. Many of those supporting 1 Angel Square actually work in the building and, the comments accompanying their votes can be summed up in the phrase:  “A great building to work in.” 

Looking ahead

As well as providing a good working environment, the new building is predicted to produce 80% lower carbon emissions and half the energy consumption of the Co-op’s former head office. This is expected to save the group over £500,000 per annum. The building’s actual performance is being carefully monitored and measured. “We have built a big research project,” said Peter Cookson, programme director of Co-operative Group, “and we will be metering it to death to ensure we optimise the building.”
  
The design also considers the more distant future, with the building having been future-proofed against the temperatures forecast for 2050. It is predicted that temperatures in summer will increase by 5%, with a 30% reduction in winter.

Triangular building with full height atrium
Home to more than 3,000 Co-op employees, the 15-storey 1 Angel Square is a striking three-sided building, with a fully glazed double skin façade curved horizontally and vertically around it. The curving walls are interrupted by a diagonal series of stepped terraces, rising towards the back of the building and forming the roof. South facing, the terraces make the most of the available sunlight.
  
The triangular building boasts a stunning, full-height atrium. Its three sides are formed from white-painted concrete balconies at each floor level. The column-free, open-plan office floors behind the balconies are bathed in light from the atrium. 

Ventilation

Around 50m3/s of fresh air is sucked into the building through three huge earth tubes buried beneath it – this helps to cool the air in summer and warm it in winter. The air is then further heated or cooled in a basement plant room, before giant fans push it up to the floor plates through vertical service cores in the atrium’s three corners.
  
Each of the service cores delivers fresh air to four of the 12 control zones into which the building’s 2,700m2 concrete floor plates are divided. To minimise the volume of air treated, carbon dioxide sensors regulate the amount of fresh air supplied to each zone.
  
A displacement system delivers fresh air to the offices through a 350mm raised floor void. As the air is warmed it rises 4m to the soffit and out of the offices into the central atrium, which acts like a giant chimney. In the atrium the air ascends to roof level, where it is drawn through a heat recovery system before being ejected.

Fuel from the Co-op’s own farms

In addition to the recovered heat, 764kW of waste heat from two 400kW combined heat and power (CHP) units is used to heat the fresh air. These are fuelled by waste cooking oil and rapeseed oil produced on the Co-op’s own farms. The CHP units also provide cooling through an absorption chiller. Cooling is delivered to the offices through passive chilled beams suspended beneath the concrete soffit.

Double skin façade
The building’s double skin façade reduces heating and cooling loads. In summer, louvres at the top of the façade open to allow the warmed air trapped between its inner and outer skins to rise up and out of the building. In winter, these louvres are closed so the façade can form an insulated blanket around the building.
  
Solar gain is mitigated by coatings on the glazing. It is also reduced by shading from the façade’s access walkways and by varying the depth of the bronze mullions on the inner face of the double skinned façade.