Using Air Source Heat Pump Technology for DHW Provision: A Sustainable Solution

Introduction

Producing hot water using direct electric fuel types is known to be inefficient overall. The conventional method involves a cylinder with a direct electric immersion heater, which is commonly found in various settings, such as restaurants, cafes, pubs, and other high-demand hot water environments. While immersion heaters are widespread, they consume a significant amount of energy. This article explores an alternative solution to hot water provision by utilising air source heat pump technology, which offers greater efficiency and sustainability.

The Inefficiency of Direct Electric Hot Water Systems

Direct electric hot water systems, including immersion heaters and instantaneous hot water provision, are known for their inefficiency. Immersion heaters, although widely used, consume a substantial amount of energy. In instances where the demand for hot water is limited, such as in small office spaces, staff toilets in retail environments, or small industrial areas, instantaneous hot water provision may be employed. However, even in these scenarios, the energy associated with their use remains high.

Exploring Alternative Solutions: Heat Pump Technology

To address the inefficiency of direct electric hot water systems, various alternative solutions can be considered, depending on the available fuel sources. One highly effective option is utilizing heat pump technology. Heat pumps work by extracting heat from the surrounding environment and transferring it to the water, providing an energy-efficient method of heating water. While there are different types of heat pumps, the most common and easily implemented one is an air to air heat pump.

Image: Metro Commercial Ltd

Introducing Air Source Heat Pump Cylinders

During surveys conducted for Energy Performance Certificates (EPCs), the most prevalent type of air source heat pump encountered is the Stiebel Eltron 300. These packaged air source heat pump cylinders have a coefficient of performance (COP) of 3.4 or 340% efficiency. In comparison, direct electric hot water heaters typically have an efficiency of 1.0 or 100%. This means that air source heat pump cylinders provide 3.4 times the efficiency of hot water provision.

Calculating Energy Performance Certificate Ratings

When determining the Energy Performance Certificate rating, the hot water demand is defined for all occupied spaces, measured in kWh/m2, and expressed in kgCO2/m2 based on the fuel type. For example, in an office setting, the demand for hot water is assumed to come from activities like handwashing and making tea. Heat losses from storage and distribution are factored in accordingly. The EPC software assumes a relatively low hot water demand for an office. Conversely, in restaurant environments where hot water demand may be higher, the efficiency of air source heat pump technology becomes even more valuable.

Sustainability Benefits of Air Source Heat Pumps

In the United Kingdom, where electricity generation produces 0.34885 kg of CO2 emissions per kWh (based on 2017 UK Government conversion factors), the use of air source heat pump technology offers significant sustainability benefits. By reducing the reliance on direct electric hot water systems, the carbon footprint associated with hot water provision can be substantially decreased. This reduction in CO2 emissions contributes to a more sustainable and environmentally friendly approach to hot water production.

Conclusion

The use of air source heat pump technology provides a sustainable solution for hot water provision in various settings. By replacing inefficient direct electric hot water systems, air source heat pump cylinders offer significantly higher efficiency, resulting in reduced energy consumption and associated CO2 emissions.

As the focus on sustainability and energy efficiency continues to grow, adopting air source heat pump technology for DHW provision becomes an increasingly attractive option for businesses and households alike.