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Passive and active cooling in concrete buildings

BREEAM and Passivhaus certified case studies use thermal mass to reduce CO2 emissions

Footprint recently attended Sustainability Best Practice at the Building Centre. Organised by The Concrete Centre, the event focused on how concrete has reduced its embodied energy and waste usage. It offered a range of BREEAM certified case studies demonstating how they incorporate concrete to provide passive and active cooling.

Speakers included:

  • Andrew Spencer, Sustainability Director at Cemex and Chairman of the Sustainable Construction Forum
  • Tom de Saulles, Building Sustainability Manager at The Concrete Centre
  • Professor Doug King, Consultant in construction, innovation and sustainability

Andrew Spencer began the event highlighting that 92 per cent of concrete production in 2011 was BES 6001 certified. BES 6001 is a standard which enables construction product manufacturers to prove that their products have been made with materials that have been responsibly sourced.


Benchmark CO2 emissions from office buildings

Tom de Saulles presented case studies of concrete floor systems used to cool buildings which incorporate passive and active systems. High thermal mass combined with these strategies enables CO2 emissions to be reduced by 4 times in office buildings. He said that successful heat storage depends on the volume of the thermal mass and the rate at which heat is absorbed. Through BREEAM and Passivhaus certified case studies, he encouraged architects to improve the energy efficiency of a building by incorporating thermal mass, a bioclimatic design and an energy efficient thermal envelope rather than relying firstly on renewable technologies. 

Headquarters of the Cambridge Federation of the Women’s Institute


Headquarters of the Cambridge Federation of Women’s Institutes by EllisMiller Architects

Architects: Ellis Miller Architects

  • Exposed precast concrete slabs
  • Natural ventilation enabled by narrow floor plan
  • Concrete walls with external insulation
  • Maximum slab cooling output 15 - 20 W/m2


PowerGen Headquarters


PowerGen Headquarters by Bennetts Associates

Architects: Bennetts Associates

  • Exposed coffered slabs with underfloor mechanical ventilation
  • Void enables thermal mass to be cooled directly by air
  • Stable internal temperature
  • Areas with high internal gains located in west and east wings, minimises air conditioning use
  • Maximum slab cooling output 20 - 25 W/m2


4 West Building at the University of Bath


University of Bath, 4 West Buiding by Stride Treglown Tektus Architects

Architects: Stride Treglown

  • In-situ concrete floors with embedded air ducts supplied by mechanical ventilation (Concretcool)
  • Summer night cooling ventilation
  • Fins incorporated inside ducts to increase heat transfer between air and slab efficiency up to 90%
  • Maximum slab cooling output 65 W/m2


Vanguard House


Vanguard House by Fletcher Architects

Architects: Fletcher Architects

  • Exposed hollowcore slabs with embedded cooling/heating pipework
  • BREEAM ‘Excellent’
  • Maximum slab cooling output 65 W/m2


Manchester Metropolitan University – Business School


Manchester Metropolitan University - Business School by Feilden Clegg Bradley Studios

Architects: FCBStudios

  • Exposed lattice girder soffit slabs with embedded cooling pipes (Hanson Coolslab)
  • Exposed thermal mass regulates internal air temperature between 21 - 26°C


Conquest House


Conquest House: refurbished office development by Emrys Architects

Architect: Emrys Architects

  • Exposed concrete slab with multi service chilled beams
  • Internal temperature controlled between 22 - 26°C during summer and 17 - 22°C  during winter
  • Heating provided by perimeter trench heaters
  • Cooling provided by chilled beams 


Watermead Business Park


Watermead Business Park by CPMG Architects Ltd

Architects: CPMG Architects Ltd

  • Exposed hollowcore slabs and mechanical ventilation with ground cooled air supply
  • Ground temperature harness (app 12°C all year) enables to heat supply air by only 6°C
  • First UK Passive House accredited office
  • Envelope U value: 0.12 W/m2K
  • Airtightness: 0.9 m3/h/m2 @ 50Pa
  • Expected annual energy savings of £20,000 (compared to previous office)

The event ended with Doug King’s presentation, who defined innovation as ‘taking products you are using to do one thing and use it to do a second thing’. He presented the CAFOD Headquarters and the BREEAM Excellent Innovate Green Office, which he claimed was ‘erected in weeks’.

Innovate Green Office


The Innovate Green Office by Rio Architects, Environmental Engineer: King Shaw Associates. Source: Doug King

Architects: Rio Architects
Environmental Engineer: King Shaw Associates

  • Exposed hollowcore precast slab with cores supplied by mechanical ventilation (TermoDeck)
  • Heat exchanger delivers heat to concrete walls and slabs to be stored during the night
  • Walls’ thermal transmittance U=0.15W/m2K
  • Emits 80% less CO2 compared to typical air conditioned office
  • Night cooling ventilation reduces cooling loads the next day 
  • Radiant and convective cooling
  • BREEAM Excellent with energy efficient fabric design, no wind turbines or solar panels
  • Maximum slab cooling output 20 - 25 W/m2     


CAFOD Headquarters


CAFOD building by Black Architecture

Architects: Black Architecture

  • Exposed in-situ concrete slabs with embedded water cooling pipes and mixed-mode ventilation
  • Stack ventilation
  • Concrete incorporates ground granulated blast surface slag (GGBS) to reduce embodied CO2
  • Active thermal mass and ventilation strategies enabled stable internal temperatures of 22 - 23°C as monitored in summer 2010
  • BREEAM Excellent
  • Maximum slab cooling output 65 - 80 W/m2


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Readers' comments (1)

  • Glad to hear that 92% of concrete production last year was BES 6001 certified. It's becoming increasingly important that we source products and materials responsibly.

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