VOICES | ALEX HILL Green hydrogen is not yet ready to be pumped into the gas grid ALEX HILL is the managing director at Whitecode Consulting Attempting to reduce noise output can lead to large amounts of attenuation and, in some cases, we have had no option but to move the plant because we cannot provide enough attenuation to reduce the noise adequately. We have noticed that this is not as much of a problem in office buildings, as most sites already have a large rooftop louvre area for the cooling plant. This generally means we are able to increase existing plant areas rather than introduce new ones. As a result, we often have roof plantrooms instead of conventional basement plantrooms. In addition, we are now supplying these sites with reversible chillers or chillers that can produce hot and cold water simultaneously, to minimise the pressures on space. Electrical capacity is the biggest challenge relative to costs. The use of heat pumps shifts the demand from the gas network to the electrical network. The power consumption is minimised because of the ratio of the heat output to energy input of the heat pumps, but we still run into the problem of the extra load placing a strain on the network. For example, a residential development with gas boilers would use around 1.5kWe per unit as a diversified load; with heat pumps, this could now be as high as 3-4kWe and, with car charging, the peak load could exceed this. GEYSER SKY Reversible heat pump with natural refrigerant Ideal for boiler replacement High comfort thanks to the variable speed technology Propane (R290), future proof refrigerant No Ozone layer impact & close to zero global warming potential Meets the highest seasonal efficiency standard Visit: www.swegon.com/uk to find out more 54 April 2023 www.cibsejournal.com The same applies to commercial developments. The 1MW of energy produced by a boiler could be replaced by a reversible chiller, but while the electrical demand for the site when being served by gas heating could be minimal, at least 350kW of additional electrical demand would be needed just for supplying pumps and ancillaries, which often requires network reinforcements. One of our sites in West London has been advised that the electrical network will only be able to supply them with 1MW per year. The project has a total load of around 10MW, meaning their site now has a minimum 10-year build programme unless we find a solution. We are beginning to talk about battery banks to support the network, or generating our own power using generators until the Grid catches up. This raises more questions about sustainability and what fuel source would be used oil or gas? These are real conversations we are having with our clients. I wish that the price of ground source heat pumps was more accessible. At this point, the capital cost is a barrier unless the client is prepared to accept that the ground source solution will provide a long-term return. With all the material cost increases, everyone is looking for the cheapest solution, but we should all consider heat pumps as the most efficient solution, even if they cost more to run.