CASE STUDY | EDGE LONDON BRIDGE supply air through the floor was driven by occupant wellbeing considerations and the systems ability to wash out pollutants from bottom to top, says Davey. It is not true displacement ventilation where the air flow is sized for thermal loads, says Davey, but it is similar and provides fresh air only from a floor-based system. This solution also ensures the buildings exposed soffits will remain free of ductwork. By contrast, a high-level air-supply solution would have mixed the fresh air with vitiated air in the space. The extract grilles are at the face of the core with controls within the riser to allow for balancing. In addition to mechanical ventilation, the scheme will incorporate perimeter openings to allow the office floors to be naturally ventilated. This was a ventilation solution developed in response to a number of drivers, Davey says. The windows will have contact sensors and will locally shut the system down in the naturally ventilated areas, says Davey. The modularity of the ceiling radiant panels (climate islands) allow them to be individually turned on and off depending on how far the natural ventilation penetrates. Of course, the biggest issue when talking about designing for occupant wellbeing at the current time is ensuring the building is designed to minimise the spread of coronavirus. The International Well Building Institute has formed a Covid-19 task force2 to inform future enhancements to the Well Building Standard, but it has yet to publish guidance on the measures it recommends to deal with the virus. The design does, however, align with the initial Covid recommendations published by CIBSE and other HVAC bodies. On a technical level, CIBSEs initial document1 says to: try to use natural ventilation weve got the ability to open the faade; and to run the ventilation system out of hours, which weve got, too, says Davey. The guidance is obviously going to evolve, but designing a sustainable, healthy building has led us to the position that is closely aligned to where the industry is very likely to end up as a result of the coronavirus. Radiant ceiling panels provide heating and cooling to the office floors. The panels at Edge London Bridge are an iteration of a solution developed and used on previous Edge schemes, including the Edge Amsterdam. We came with a strong Covid-19 must now be taken into account when designing for occupant wellbeing preference for radiant heating and cooling, because we know it is sustainable and much better from an occupant-comfort and health perspective, says Heersche. The radiant panels will be supplied with heat and coolth using a combination of heat pumps and chillers. Davey says the site is too small to get anything meaningful from the ground, so hes looking at how energy can be recovered from the system instead. The cooling system is going to have a constant demand, particularly from tenants IT loads throughout the year, so Im looking at how we can recover that heat for use in the buildings heating and domestic hotwater systems, he explains. In addition to the radiant heating/cooling elements, the ceiling panels incorporate light fittings and eight sensors, including ones for motion detection and to measure light levels, temperature and humidity. The output from the ceiling panels will form part of the digital infrastructure that will connect everything and everyone within the buildings walls; the system is fundamental to what makes such buildings smart (see panel, Built-in intelligence). Work is set to start on the construction of what is planned to be Londons most sustainable office tower next year, with completion in 2024, when the developer expects the first occupants will take up residence. Heersche is optimistic the combination of sustainability and wellbeing will be a winning formula in London. Intrinsically, sustainability and wellbeing are the right things to do, he says. It also makes sense from an occupiers perspective, because the cost of rent compared with the cost of paying their workers means that it is an absolute no-brainer to pay a small amount more on rent if you can have a more productive workforce. CJ References: 1 Coronavirus Covid-19 and HVAC systems, CIBSE, April 18 2020 bit.ly/CJJUNE20Edge1 The Edge Olympic building in Amsterdam 2 Task force on Covid-19 and other respiratory infections, Well bit.ly/CJJune20Edge2 24 June 2020 www.cibsejournal.com CIBSE June19 pp22-24 Supp Edge London Bridge.indd 24 22/05/2020 17:35