New PFI hospitals cut energy use with natural ventilation and lighting
Natural light and ventilation for Fromeside Hospital in Bristol are provided by Monodraught SunPipe and Windcatcher units.
The environmental benefits of natural ventilation and natural daylight are being exploited at two new major PFI hospitals in Bristol by installing Monodraught Windcatcher and SunPipe systems. They are Callington Road Hospital, which was conceptually designed by BDP, and Fromeside Hospital by Devereux. Hurley Palmer Flatt was the M&E consulting engineer. Part of the conditions of these PFI schemes is to reduce energy costs by 20%, and main contractor Rydon Construction spent much time and resources seeking products to meet this target. David Greggan of Rydon Construction told us, ‘Fromeside is currently being commissioned to test for energy savings. We already know the specific energy targets will be within the criteria set out initially, and we are quite convinced that we could not have achieved this without the help of Monodraught’s products.’ It is estimated that daytime electricity costs for lighting can be reduced by 75% using SunPipes to direct light from ‘domes’ on the roof to translucent ceiling fixtures. Both hospitals also make maximum use of Windcatchers to provide energy-free natural ventilation and eliminate the need for air conditioning. Clean, fresh air is entrained at roof level and delivered to spaces below through compartmentalised ducts. Air is extracted through other compartmentalised ducts in the Windcatchers. Toilets and windows in both hospitals have no windows and utilise mechanical extract. Windcatchers serve adjacent corridors to provide makeup air for the toilets and windows. The BEMS in each hospital controls the rate of natural ventilation by adjusting dampers in the Windcatchers. They start to open at 16°C and open a further 10% for every 1 K rise in temperature. In winter, the automatic dampers are controlled according to carbon-dioxide levels and close to 5% to provide trickle ventilation. The largest Windcatchers are in the Banana Building, the administration and office block of Fromeside Hospital. There are two units, each 1500 mm square. Monodraught products are supplied with a no-quibble 25-year guarantee.