HEATWAVES | COOLING Martin Fahey, head of sustainability, Mitsubishi Electric M ost UK buildings simply arent prepared for the high temperatures we have seen this summer, but there are a number of things that building operators can do to keep occupants and critical infrastructure safe and cool, without ramping up energy use. The first and simplest thing is to turn up the thermostat. Air conditioning in the UK is often set at 21C or lower, and the temptation when its hot outside is to turn the thermostat down even further. If it is 35C+ outside, however, an internal temperature of 23C, 24C or higher will still feel much cooler and, more importantly, it will consume less energy, giving you occupant comfort without increasing bills. Effective maintenance is another easy and highly beneficial way of maximising comfort and minimising energy use. Ensuring that Anastasia Mylona, head of CIBSE research P assive cooling solutions need to be prioritised. Control of solar gains (through shading), maximising natural ventilation (by ensuring cross-ventilation), and the use of insulation and thermal mass with sufficient night-time cooling have proven to be the most effective passive cooling techniques in hotter climates for centuries. Orientation and proximity to green and blue areas are additional, well-established cooling techniques for example, reducing glazing in the south/west/east, introducing internal atria with overhangs and water features, and green roofs and walls can all contribute to keeping buildings cool in the summer. Buildings in dense urban environments tend to suffer most from overheating, and face noise, security and air-quality restrictions. Although the same passive principles apply, natural ventilation might not always be appropriate or safe. Mixed-mode solutions, such as a combination of natural and mechanical ventilation options, could be considered in such buildings. Noise, pollution and security concerns could be reduced by careful consideration of the placement of larger windows. Ultimately, keeping our buildings cool is an urban planning issue. If we succeed in keeping our cities cool, the buildings will always have access to natural ventilation and, as such, to natural cooling. This can be achieved by introducing more green spaces and urban shading, green walls and roofs, cool building material and water features, and less air polluted by maximising wind patterns, reducing car traffic and increasing sustainable travel. Based on future climate projections, if we continue expanding and building our cities the way we are, they will most likely become uninhabitable over the summer by the end of the century. filters are clean and outdoor units are not blocked will allow them to work efficiently. Many modern commercial air conditioning systems also offer the ability to maximise heat recovery. This means that heat energy recovered from cooling spaces for occupant comfort can be transferred to a hotwater supply, or moved to parts of a building that may still need heating. Of course, this can work all year round, with essential cooling for critical IT infrastructure producing energy that can be used to heat other parts of the building. With modern mixed-use buildings in our towns and cities, this approach can be used to enable heat energy from cooling gyms, offices and retail outlets to be used to provide hot water for the apartments above. In addition, clever use of natural ventilation and mechanical ventilation with heat recovery can help lower peak temperatures inside buildings, reducing the initial requirement for cooling systems along with energy use. With these levels of summer temperatures likely in future, we need to look at designing urban spaces to stop them becoming heat spots in the first place, with solar shading, natural ventilation and other physical attributes such as trees and green walls to provide cooling and ventilation. Mark Beaumont, head of strategic accounts UK, building products, Siemens Smart Infrastructure H igher temperatures are here to stay for the foreseeable future, so we need to start looking at how we mitigate the impact on our journey to zero carbon through energy management and green credentials reducing our water usage, among other things. We should, of course, be looking to capitalise on the longer hours of sunshine and the higher, more sustained wind speeds, which are related to temperature change. Research by a team at Princeton University shows that the average wind turbine produced 17% more power in 2017 than in 2010. If current trends continue, by 2024 wind turbines could generate 37% more power than they do today. If your site can support solar or wind generation, it may be more viable now than ever before. You might also consider water collection and planting for shading. Managing the efficiency of your HVAC system can mean that you do not use as much energy and water, even when it is hotter. Avoiding having the cooling running at maximum while you have the windows and doors open on a hot day may sound like common sense, but it happens a lot more than you might think. It is also frequently the case that the HVAC target temperature is set too low on a hot day, or that the thermostat is not responsive enough. Most people are comfortable at around 18C to 22C. At 17C or less, they will be looking to wrap up for warmth or to let in some outside heat. It really is important to keep your HVAC system serviced and to have a good building management system running things. 76 September 2022 www.cibsejournal.com CIBSE Sept 22 pp75-76 Cooling in hot climate.indd 76 26/08/2022 14:04