London, once considered a low-rise city, has experienced a record number of tall building completions in recent years. As a result of planning decisions in favour of high density residential development, the skyline is being transformed. This picture is being repeated to varying degrees in other major cities across the UK.
Recent figures illustrate the dramatic changes underway. According to the 2020 London Tall Buildings Survey, some 60 high-rise buildings, including both residential and commercial, were completed in London in 2019. That is more than one a week.
Despite the economic uncertainties due to Brexit and COVID-19, there are more than 500 high-rise buildings at various stages of the planning process across the UK. Over 80% of these are in London and the remainder concentrated in large cities, such as Birmingham, Liverpool and Manchester.
While construction safety standards are under review post-Grenfell, environmental imperatives are transforming the approach to building design and HVAC services for high-rise developments.
New targets and regulations are aimed at improving thermal performance, increasing equipment efficiency and boosting use of renewables to enable the step-change required to deliver the ultimate goal of net-zero-carbon buildings.
In addition, the pandemic has underlined the importance of indoor air quality (IAQ) and the contribution that HVAC systems can make to supporting healthy buildings.
In response, the industry is rising to these challenges on a number of fronts. This includes transitioning to a new generation of lower Global Warming Potential (GWP) refrigerants, redesigning equipment to further improve performance and optimise occupant well-being, and harnessing both existing and new technologies to help support healthy buildings.
On refrigerants, the new family of environmentally focussed fluids being introduced for use in chillers and heat pumps has GWP ratings strikingly lower than the refrigerants they replace. For example, refrigerant R-515B, which Carrier is pioneering in HVAC applications, has a GWP of less than 300, approaching one-fifth that of R-134a, the refrigerant it replaces.
The refrigerant is also more energy efficient, delivering a double benefit for the environment and reducing running costs for end users. In addition, R-515B is classed as an A1 refrigerant, therefore it has no flammability issues compared to some other refrigerants. The first application of Carrier R-515B chillers in the UK is currently underway on a project in Liverpool.
Improved system design and centralisation are also delivering big improvements in energy efficiency for high-rise buildings. High density accommodation lends itself to district cooling and heating schemes, where use of heat pumps and economies of scale help reduce unit costs for residents, as well as cut overall building carbon emissions.
Carrier has contributed to a number of such major schemes that harness energy from boreholes or river water in the capital, and for all the reasons outlined we foresee significant expansion in these approaches in the future.
At the equipment and component level, advances in design are yielding improvements that optimise living space and well-being for occupants, as well as help to maximise revenue for developers.
For example, ultra-slim fan coil units now available enable lower ceiling void heights, liberating valuable space within the building envelope. This can be used to create higher ceilings, giving apartments a premium feel that improves the sense of well-being for residents and brings in higher rents for landlords. The extra space can be also used to add additional storeys within a permitted building height, delivering higher returns for developers.
Improvements in core HVAC technology continue to improve flexibility and extend application in tall buildings. Variable Refrigerant Flow (VRF) air conditioning is a case in point, where, due to improvements in design and performance, maximum pipe runs have been extended in recent years.
Premium VRF systems now offer a maximum pipe length of up to 1,200m, enabling this highly efficient and cost-effective technology to be applied in multiple-storey buildings, which in the past would have been the preserve of air conditioning chillers alone.
The importance of well designed and implemented building services for IAQ has long been known. However, the emergence of COVID-19 has highlighted how HVAC solutions can contribute to maintaining healthy buildings.
In this regard, technologies such as high-resolution HEPA and activated carbon filters, UV-C light disinfection and modern ionisation systems have come to the fore. As stand-alone systems, or in combination for deployment in potentially higher-risk areas, they can help support healthy buildings and provide reassurance for those who live and work in them.
My own company has brought together a suite of stand-alone and integrated technologies to deliver support for building owners and managers under the Carrier Healthy Buildings programme.
Despite the modest slow-down in construction resulting from current economic uncertainties, there seems every likelihood that the dynamics behind the expansion of high-rise buildings will continue to drive development in the future. The healthy pipeline of buildings currently in the planning process, and the resumption of work now taking place on projects on the ground, strongly supports this.
Our industry is working hard to ensure we have the solutions needed to deliver healthy, comfortable, efficient and productive buildings. Carrier and Toshiba are pioneering new approaches in many of the key areas touched on, all directly applicable to the particular needs of tall buildings.
This process, which draws on global resources in research and development and decades of expertise, will continue in order to meet whatever challenges and opportunities arise in this dynamic and rapidly evolving sector.