Modern Building Services

MODERN BUILDING SERVICES DECEMBER 2022/JANUARY 2023 29 Climate change mitigation can also embrace designs to reduce or remove the need for mechanical HVAC systems altogether by, for instance, laying out the building in an orientation that decreases solar gain or adapting the space to facilitate natural ventilation and/or using the thermal mass of the building to moderate internal temperatures. Another way to lessen the effects of global warming is by installing air conditioning systems, although a major criticism of this is that it creates a vicious circle – more air conditioning means more carbon emissions which means more climate change. Relentlessly pumping carbon emissions into the atmosphere is at the root of the climate emergency we are experiencing, and cooling is amajor cause of this. That’s why the focus has been on creatingmore sustainable air conditioning systems. Sustainable cooling The Environmental Investigation Agency 6 – an international non- governmental organisation founded in 1984 in the UK by environmental activists – is working to promote HFC-free technologies by addressing barriers to their uptake and sharing information with governments, manufacturers, end users, and other stakeholders. It is also helping raise awareness of the dual benefits of efficient HFC-free technologies. One of the best HFC-free refrigerants is carbon dioxide (CO 2 ). CO 2 , aka R744, is a natural refrigerant with an ozone-depleting potential of 0 and a global warming potential of just one. CO 2 offers a high refrigeration capacity and lower pressure drops in pipework and heat exchangers. It is generally non-corrosive, non-flammable, and exhibits low toxicity. Furthermore, it is inexpensive to produce and widely available. Finally, and crucially, there is no legislation currently planned to phase it out. A global transition towards the best cooling technologies for all new air conditioning units could reduce total electricity demand by 25 to 33% in 2030, achieving cost reductions of US$260 billion (£235bn) and emissions reductions of up to 575 MtCO 2 , according to the Climate Action Pathway: Net- Zero Cooling report5 (see above). It adds: “Doubling the energy efficiency of air conditioning by 2050 could save up to US$2.9 trillion in a reduced generation, transmission and distribution costs alone and would reduce the need for 1,300 GigaWatts of additional generation capacity to meet peak demand, the equivalent of all the coal-fired power generation capacity in China and India in 2018.” Heat recovery Another practical idea to help mitigate climate change, while also reducing the carbon emissions that create it, is heat recovery. This can be particularly useful in areas containing facilities that produce a lot of unwanted heat 24 hours a day such as data centres. Rather than building large data centres in cities, one idea is to construct smaller facilities on the edge of towns. These local structures offer significant energy- saving potential because, rather than rejecting the heat, it can be used for a district heating loop or to serve neighbouring properties. A recent data centre project in Tower Hamlets, London includes a heat recovery loop to serve a residential development adjacent to the data centre. Four-pipe, polyvalent heat pumps 7 allow simultaneous and independent cooling and heating from the same plant, including domestic hot water production. This concurrent production of chilled water and hot water in the heat recovery mode effectively doubles the combined efficiency of the unit. With data centres so essential to modern life and such voracious users of energy - as much as 40% of the total operational costs for a data centre come from the energy needed to power and cool the colossal amounts of equipment these facilities require - maintaining an equilibrium between the two opposing forces of cooling demand versus environmental concerns, is key. The polyvalent approach is beneficial to a wide range of buildings, not just data centres. In fact, hundreds of similar heat pump systems have been built in the last 15 years in residential and commercial buildings, offices, industrial complexes, hospitals and hotels. Water temperatures can be boosted locally if required with high- temperature heat pumps, immersion systems or point of use heaters. Whether heating or cooling, improving the efficiency and reducing the carbon footprint of all of our HVAC processes will contribute positively to the wider issue of increasing temperatures. Source 1 https://tinyurl.com/yvb66dn5 2 https://tinyurl.com/yeyt6y98 3 https://tinyurl.com/2t9vs3me 4 www.ipcc.ch/report/ar6/wg1/#SPM 5 www.carbontrust.com/resources/ the-climate-action-pathway-for- net-zero-cooling 6 https://eia-international.org/climate/ sustainable-cooling-technologies/ 7 https://klima-therm.co.uk/ products/heat-pumps/polyva- lent-heat-pumps/ More information can be found at www.klima-therm.co.uk FEATURE NET ZERO