Hybrid systems are an innovative decarbonising solution that can act as the first step towards limiting carbon emissions on projects that may not be able to fully adopt decarbonising technology such as heat pumps alone. UK energy policy is aimed towards the reduction and eventual nullification of fossil fuels. During this transition away from coal, oil, petrol and high carbon gases and towards renewables and alternative energies, how can UK projects comply with future governmental policy in a retrofit environment and still ensure a plentiful supply of hot water?
One possible solution is to invest in a hybrid system, which accepts two forms of fuel or power to ensure a cost-effective and smooth operational performance that produces heat and hot water.
Hybrid technology accepts two separate forms of fuel or power. One could be either natural gas or LPG, for example, alongside solar thermal panels or a heat pump. Hybrid systems are designed to optimise factors such as outside temperature, current energy prices, property heating and DHW demand. Instead of relying on one fuel source or technology such as renewable electricity and heat pumps, hybrid options instead use two forms of power or heat generators to complete daily functions inside commercial applications.
For smart DHW hot water systems such as the continuous flow water heaters used with heat pumps, the renewable heat generator provides the base load as the water heaters ‘top up’ the temperature. This approach is inherent within the system and ensures optimal performance.
Using two separate energy sources offers a range of benefits for UK retrofit projects. The first advantage of this is from a financial viewpoint: as electrical costs are higher than natural gas, using a system that accepts both renewable electricity and traditional fuel sources means that costs could be lower and more manageable when compared to an exclusively electrical system. From a capital expenditure perspective, the cost of a hybrid system is often lower than a full electric system, creating lower whole-life costs.
In terms of operational performance, a hybrid heating and hot water system combines two technologies that ensure energy efficiency while supporting operational consistency. A hybrid system will benefit from the incorporated heat pump or solar thermal technology during favourable weather conditions while using the auxiliary appliance during periods of colder conditions. This will optimise the strengths of each technological approach in separate weather condition circumstances; the addition of a combustion-based water heating technology will boost the renewable base load to ensure DHW performance.
A further benefit for the end-user is that the lifecycle of each technology is lengthened. As each does not have to apply its full effort to satisfy demand, component and overall system longevity will be increased due to a lessening of the required workload.
Hybrid systems offer a practical route for environmental objectives to be accomplished. As not all customers can fully financially commit to decarbonising practises, hybrid technologies that incorporate both renewable and traditional systems and fuels are able to bridge this gap. This practical approach introduces customers to the idea of alternative and clean energies, maintaining control over energy costs by relying on conventional and more cost-effective methods of energy usage.
The hybrid approach can also be instrumental within buildings that do not have the space, infrastructure or plant room facilities for full electrification and the increase in stored hot water volumes.
A hybrid system is comprised of several features, components, technologies and fuels. The main elements of a hybrid heating and hot water system are:
• Heat pump: The renewable backbone of the system. Most hybrid systems use air source heat pumps (ASHPs). Ground source heat pumps (GSHPs) are also viable for specific applications, particularly in commercial settings.
• Condensing gas boiler/water heater: A high efficiency water heater serves as the auxiliary heat source. Modern condensing water heaters are designed to extract as much heat as possible from combustion gases, increasing energy efficiency.
• Solar panels: When solar thermal collectors are included, they can contribute heat to the system directly or to a buffer tank. This heat can then be drawn upon before the system calls for either the heat pump, gas boiler and water heaters, making it more energy efficient.
• Control unit/smart thermostat: The ‘brain’ of the hybrid system, responsible for deciding which heat source to use based on real time conditions. Many units are integrated with weather compensation and predictive algorithms.
• Buffer tank/hot water cylinder: Optional but recommended for systems that provide domestic hot water (DHW). The buffer tank helps to smooth out demand fluctuations and improve efficiency. Other cylinders can include buffers for minimum water content and for additional hot water demand.
• Sensors and meters: These measure temperature, flow rates, and energy consumption, feeding data back to the control system to enable automated switching. Hybrid system water heating is a viable method of cost and carbon reduction that offers seamless operational performance. UK customers who cannot afford to fully comply with current UK decarbonising energy policy should consider investing in hybrid technology that can provide hot water for either a domestic or commercial dwelling.
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