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Starting the sustainability journey with hot water

Every commercial organisation requires hot water and for many, it is a business-critical service. From hospitals to hotels, schools, universities, restaurants, leisure centres, shops, and offices, the range of property types and usage means the demands for hot water are many and varied. As such, the provision of hot water is complex, potentially more expensive and can be extremely energy intensive – accounting for as much as 30% of a building’s daily energy demands – which makes addressing its sustainability both important and challenging.

Most existing commercial facilities will typically run successfully on a system based around gas-fired water heaters, which, despite being highly efficient and cost-effective are not sustainable. This is why for more recent construction projects the preference has been to move to electric water heating to take advantage of increasingly less ‘dirty’ grid energy. For those wanting to achieve net zero in existing buildings there are two options, electrify all equipment on the basis that the electricity grid will become zero carbon, or change natural gas to a carbon-free gas such as Hydrogen.

The application of hydrogen still has a large question mark over it. At Adveco, we accept it has an important role to play and is likely the easiest and most cost-effective way to quickly bring sustainability to existing gas-grid-connected commercial sites that have high demands for energy or hot water. If you have a gas connection, the advice is not to remove it as it leaves an alternative path for future-proofing some or all of an organisation’s energy demands.

Today, electrifying all equipment is the most likely option, but it does have implications for running costs, as electric tariffs are on average 3.8 times more costly than gas. For example, a 150-bed hotel changing from gas to direct electric will reduce carbon emissions by 42% but the yearly hot water running costs could increase from an average of £6,500 to £25,000.

Unlike space heating, which is influenced greatly by the building fabric and especially insulation, water-heating applications are year-round systems that can immediately benefit from the addition of renewables and are one of the best ways of making active carbon savings today, and if planned properly can help offset the costs of direct electric water heating.

Deploying either heat pumps or solar thermal as a renewable to provision the hot water system’s initial preheat is the most logical approach. This allows for either reducing or eventually removing the need for gas afterheat in older properties reducing energy demand and emissions. Those sites on grid electricity also gain further carbon savings, reduced running costs and, if system demand is great, can help pass Part L during building works for new projects or large scale refurbishments.

Both heat pumps and solar thermal technologies offer a low maintenance way of achieving reduced emissions targets, with solar thermal, which is essentially free to operate, also helping to control operational costs by offsetting the need for electrical top-up water heating.

This variety of options for domestic hot water (DHW) systems in commercial properties is also increasing their complexity. That leads to more chances of systems becoming oversized due to a poor understanding of needs and concerns over ensuring system redundancy. We see this when gas is switched to like-for-like sized electric alternatives. This would result in higher, unnecessary capital expenditure and operational costs for the life of the system, potentially counteracting the efforts to introduce sustainability. To avoid issues of poor sizing, and incumbent costs, a thorough understanding of a property’s daily hot water peak and general demands is a necessary starting point for any sustainability project that is going to address hot water emissions.

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