The headline figure of 600,000 annual heat pump installations by 2028 has made headlines in the construction industry.
It’s an ambitious target that will change the face of heating in the UK by tapping into our increasingly green grid.
However, not so much has yet been written about heat networks and communal heating systems. But these are also on the government’s ‘To do’ list in its Net Zero plans.
The aim is to raise the presence of heat pumps from around 2% of our heating systems (about 14,000 installations across the country) to 52%.
It’s another significant objective that will mean thinking very differently about the design and execution of heating systems in our cities and towns.
We can create synergies that will help us tackle our environmental and energy issues on several fronts at once.
It’s a question of scale
The main difference between heat networks and communal heating is one of scale.
Heat networks can stretch over whole estates, or even towns.
A communal heating system generally works in single multi-residential building which may also include some non-residential elements such as retail outlets, offices or a gymnasium.
The heat networks and communal heating systems in operation today have an energy centre which creates hot water to supply DHW and space heating.
The energy centre often uses a gas boiler or perhaps CHP as the heating source.
In a communal heating system, each apartment will have a heat interface unit (HIU) which takes the hot water circulated from the energy centre at 70oC and makes it usable for DHW and space heating.
A low-carbon future
However, looking to the future where we expect to see a rapid growth in low-carbon heating, a new generation of heat networks and communal heating are on the rise: Fifth Generation or ambient loops.
These use the principles of a heat network, but with heat pumps in the energy centre and individual buildings or apartments on the ‘loop’.
The main difference is that rather than circulating water at high temperatures, an ambient loop operates at much lower temperatures, between 10oC and 30oC.
It’s a major difference made possible because heat pumps in each apartment or building on that loop can use the low temperature water and increase it to provide instantaneous hot water and space heating.
The energy centre on an ambient loop can also be served by a heat pump. This can be air-to-air or water-sourced if there is a nearby river or lake.
A new product for a new age
What’s even more useful is that rather than simply pushing heat out from a boiler, the ambient loop can also receive heat from other sources, including heat rejected from cooling systems.
This makes ambient loops ideal for multi-residential buildings where shops or offices in the same building use VRF air conditioning for cooling (for example).
Rather than rejected heating from those spaces simply being lost into the atmosphere, it can be redirected into the ambient loop to generate hot water for apartments.
Here at Mitsubishi Electric, we recently launched our own water-to-water heat pump, the Ecodan Hydrodan to tap into the potential of 5th generation heat networks.
It’s a heat pump with built-in water cylinder that has been specifically designed for this new era of ambient loops – made to be easy to install and maintain as well as offering very quiet and energy efficient operation.
Reducing primary energy
Not only does this approach make the cooling system more energy efficient and sustainable, but it also reduces the requirement for primary energy input to the loop. This is an enormously important factor to consider.
As we shift our heating away from gas, and as our grid relies less on gas-fired power stations, we need to ensure our electricity grid is not placed under too much pressure.
By reducing the need for electricity input to the next generation of heat networks, we can ensure our journey to net zero is as smooth as possible.
By taking well-established technologies such as heat networks and heat pumps and applying them in novel ways, we can create synergies that will help us tackle our environmental and energy issues on several fronts at once.
Dave Archer is National M&E Manager