OVERHEATING | VENTILATION AND ACOUSTICS Figure 1: Building services overheating solutions for different external noise risks be necessary. Various building services alternatives to full mechanical cooling could limit overheating by providing peak lopping, as well as being cheaper and simpler. Potential standalone options for individual houses or apartments in residential blocks that do not require central cooling include: n Enhanced mechanical ventilation with heat recovery (MVHR), boost mode n Additional mechanical ventilation: typically four air changes per hour, in our experience n Split/DX cooling units n MVHR with dehumidification n MVHR with mini-heat pump cooling. If these measures are not sufficient for passing TM59 without closed windows, there are further options to offer tempered cooling with a central cooling system for apartment blocks. These remain cheaper than full mechanical cooling and use less energy. They are: n Underfloor cooling n Chilled ceiling panel cooling n Cooling coil in MVHR supply air duct n Mini-heat pumps with central condenser water loop n VRV and fan coil unit (FCU) n Central chillers and multi-zone FCUs. With some of these options, however, certain rooms may still not pass TM59. In such cases, hybrid ventilation could be considered with a standard MVHR unit on boost mode, alongside enhanced attenuation, for cooler parts of the UK, plus additional cooling for hotter parts. MVHR units of a size to meet Part F for boost ventilation could be used, but with enhanced acoustic attenuation. This would allow it to run for long periods in summer, limiting overheating. Conclusion To provide comfortable, healthy homes, developers, design teams and planners should design to limit overheating and noise together. Design teams should reduce solar gains and consider tempered cooling solutions to avoid full mechanical cooling. CJ RECOMMENDATIONS Development of a recognised, holistic industry design guide, including overheating and noise. Base noise criteria in planning on a recognised standard, possibly time- or dose-dependent, with an absolute maximum noise level. This could be added to Part E of the Building Regulations to include internal noise levels. Revise the fabric energy efficiency calculation in art L1 to take more account of cooling energy and limiting overheating. Consider alternatives to average daylight factors planning policy. KATHERINE HOLDEN MCIBSE is an executive engineer at Sweco. This article is based on an opinion paper she presented at the CIBSE Technical Symposium in April 2019 on Limiting Residential Overheating in Noisy Environments bit.ly/2kNpS H Figure 2: Local tempered cooling solutions with closed windows, shown in order of increasing cost in complexity Figure 3: Tempered cooling solutions with central cooling system, shown in order of increasing cost in complexity 44 October 2019 www.cibsejournal.com CIBSE Oct19 pp43-44 Sweco.indd 44 20/09/2019 16:19