FOCUS: HOTELS & LEISURE


Preparing existing hotels for the Net Zero journey


Andy Green, technical director at Baxi Commercial Solutions, looks at the Net Zero carbon challenge facing hotels and the opportunities to drive down emissions through more sustainable hot water generation


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n the hotel sector, as in most industries, sustainability has shot up the business agenda in recent times, and it’s easy to understand why. Green credentials give hotels a more competitive edge with eco-friendly guests, while implementing improvements to heating and hot water system efficiency reduce energy consumption, helping mitigate soaring energy prices. Legislation is also driving the move to more sustainable hotel building performance. In a shift towards a Future Buildings Standard, Approved Document L of Building Regulations now requires all new non-domestic buildings – including hotels – to produce 27% fewer carbon emissions relative to 2013 standards. Tighter minimum efficiency standards for new and replacement thermal assets have also been brought in to improve the efficiency of existing non-domestic buildings.


Consequently, new hotel buildings will be designed to support Net Zero operation, often through passive energy measures and renewable technologies such as electric heat pumps to deliver low carbon heat. But in existing hotels, the transition to low carbon heating and hot water provision is often more complex. As each building will have its own unique requirements, choosing the best approach to reducing a hotel’s carbon footprint, without compromising on comfort and performance, can be daunting. So how to tackle the challenge?


Getting the infrastructure in place


Experienced manufacturers can help hoteliers understand the options for immediate and longer-term gains to enable them to plan their roadmap to the energy transition. Realistically, full decarbonisation is unlikely to be achieved overnight in many older buildings.


Heat pumps, for example, perform best in buildings designed from the ground up to use low temperature heating. This means that most existing hotel buildings will need to be adapted through a series of steps to make them heat- pump ready.


A good starting point is to reduce heat loss and lower heat demand, usually through fabric improvement. Identifying achievable opportunities to improve the efficiency of the heating and hot water system is the next logical step.


Let’s consider domestic hot water generation, one of the natural targets for improvement in many hotels.


Targeting hot water production


Hotels need to supply large volumes of hot water which pushes up energy demand. The hot water usage tends to follow a pattern of extremely high peaks in the morning and evening with periods of low demand in between. In older, larger hotels that rely on central boiler plant and a calorifier for both space heating and hot water, separating out the heating and hot water demand might be a consideration. This has two major benefits. First, installing an accurately sized, dedicated water heater for point-of-use hot water will provide a more efficient and effective solution to meet the hot water demand. Second, the boilers serving the heating system can be operated at a lower flow temperature through direct weather compensation, promoting condensing efficiencies of the heat generator. This will improve overall system efficiency and prepare it for the addition of heat pumps at a future date. Many hotels use traditional direct-fired water heaters as one of the most efficient means of meeting the sudden peaks in hot water demand as they can deliver large volumes of water in a short time. A major benefit of this


approach is that it reduces energy loss between peak periods as the system will only use energy when hot water is required.


Upgrade to more energy efficient equipment


However, recent revisions to Approved Document L of Building Regulations now effectively rule out non-condensing water heater replacement in the vast majority of buildings, in favour of more efficient condensing models. So, if the hotel relies on non-condensing water heaters, it’s advisable to start planning to upgrade to condensing water heaters now to improve the efficiency of the hot water system and protect business operation.


Hybrid solutions


Once the building is heat-pump ready, and budget is available, hoteliers might consider installing an air source heat pump (ASHP) to provide pre-heated water to the direct-fired water heaters. Again, early preparation is essential. Where will the heat pump(s) be sited? Hoteliers should allocate external space for the heat pump and ensure that the area is sufficiently flexible to allow a choice of manufacturer or heat pump model.


Electrical connections must also be evaluated. Is there sufficient capacity now or do plans need to be put in place to increase it?


Design benefits


Using hybrid heat pump solutions for domestic hot water generation brings many advantages. The heat pump could be used to pre-heat a storage vessel, sized to contribute to the peak demand, which will feed the water heaters. This design satisfies the hot water requirements safely and efficiently by reducing the amount of energy required to raise the hot water temperature to a useable and safe level, with the majority of demand being met through renewable energy.


In fact, it has several advantages over a system designed around wholly electrical equipment in hotels with limited spare electrical supply capacity. With the latter, a larger thermal store would be required to meet peak demand, due to longer recovery times. This could cause logistical problems in terms of storage. Energy usage would also be higher than point-of-use water heaters which only use energy when hot water is needed. What’s more, direct-fired water heaters, especially those supplied with full legionella programmes, ensure safe, hygienic hot water by maintaining the hot water system at above 60˚C. At present only a small portion of ASHPs can efficiently generate temperatures high enough to store domestic hot water above 60˚C or higher, so some form of legionella mitigation might need to be considered.


Working together


With no silver bullet solution to meet their buildings’ demand for large volumes of hot water more sustainably, hoteliers will look to the building services industry for advice and support to set them on their Net Zero journey. The route they chose will depend on many factors, including the building type and the budget. As heat experts, we look forward to working with designers, consultant engineers and hoteliers to assess the most appropriate stepwise refurbishment programme to decarbonisation on a project-by-project basis.


24 BUILDING SERVICES & ENVIRONMENTAL ENGINEER AUGUST 2022 Read the latest at: www.bsee.co.uk


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