How to Maximise Energy Efficiency from Heat Pump Systems
The energy efficiency of air source heat pumps is not in doubt; they are up to three times as efficient as a gas boiler. But to maximise the energy efficiency of a commercial heat pump solution, there are four key aspects that need careful consideration: building fabric, building services, heat pump system design, and usage.
The design of a building and the material it is made from will impact the energy efficiency of your commercial heat pump solution. The more thermally efficient the building, the more energy efficient it will be. Consideration therefore needs to be given to all aspects of building fabric, including insulation, glazing, etc. Undertaking a building survey will enable you to identify heat loss within your building and remedial work that needs to be done to reduce this.
A commercial building survey should also address the services within that building, including the existing heating system to see if it is fit for purpose when it comes to running efficiently with a heat pump solution. Key to the success of a heat pump heating system is the ability for the building's heating system to be able to operate on lower temperatures. That means correctly sized radiators.
Heat pump system design
It might seem like stating the obvious, but air source heat pumps are not gas boilers; the specification and system design is different. If you treat them as the same thing, you are not going to reap the true energy efficiency benefits of a commercial heat pump solution, your electricity costs are going to rise and you may well end up with some unhappy, chilly occupants.
To correctly specify a heat pump, the thermal efficiency of all the areas to be heated – including aspects such as window sizes and the building’s materials - needs to be measured and calculated. It needs a skilled person to conduct a survey of this nature.
In the world of gas boilers, it’s standard practice to oversize them, which doesn’t really matter as the boilers just work less hard. Oversizing a heat pump system design however doesn’t mean you’ll benefit from more heat, but it does decrease energy efficiency, so correct sizing matters.
The location of a heat pump installation is also completely different to that of a gas boiler, as a commercial heat pump solution requires external air flow to function so must be installed externally. Units are commonly installed at ground level or on the roof depending on the building type, but the key requirement is adequate clearances to ensure good air flow.
Another aspect that differs from gas boiler installations is the use of a buffer tank, but this has an important role to play when it comes to heat pump energy efficiency. A buffer tank keeps a minimum volume of water ‘in circuit’ at times when the heating load is very low. It prevents the heat pump system from short cycling and provides a bypass route to maintain the minimum flow rate through the heat pump if most of the heating zones have shut down. Short cycling not only impacts energy efficiency and comfort levels but can also reduce compressor life.
Heat pump usage
As with all commercial heating systems, understanding the building and its usage is important to identifying what you want to achieve from your heating system. This then needs to be translated into a good control strategy for maximum energy efficiency. Monobloc air source heat pumps are capable of everything that boilers are capable of when it comes to control and can readily be integrated into a BMS.
Educating the building occupants as to the new heating system is an important consideration. With a gas boiler, if the temperature drops you can turn it up. With a heat pump system design, you need to maintain a base heating temperature over a long period of time. Opening windows or messing around with thermostats will cause an imbalance in the system that will take time to rectify.
Vivre le difference!
Heat pump installations will continue to increase across the UK’s non-domestic buildings as an energy efficient source of heating. But an air source heat pump is not a boiler and a like for like replacement is not possible. To make the most of a commercial heat pump solution, addressing the factors outlined above is essential if you are to maintain both a comfortable temperature and energy efficiency.
For more information on the basics of heat pumps, contact your Area Sales Manager about completing our CIBSE approved CPD: Intro to heat pumps - technology and principles