Showcasing our expertise: heat pumps – the way forward to decarbonisation
This piece was originally published in Energy Manager Magazine, February 2024
Author: Matthew Everett, energy and carbon analyst
In the UK the built environment accounts for about 25% of our greenhouse emissions and to tackle climate change it’s clear that to reach our net zero ambitions we need a tight focus.
We also need a realistic focus – together we must meet legally binding targets of reducing carbon emission by 75% by 2035 and achieve net zero by 2050.
How realistic is this? And how are we going to get there?
At Salix we are working hard with the public sector across the country to decarbonise estates and provide a whole series of deadlines to reduce carbon emissions over the next few years.
One of our flagship schemes is the Public Sector Decarbonisation Scheme. This is aimed towards more electrical based solutions across public sector buildings which includes large estates across the country from NHS trusts, to universities, schools and leisure centers.
The scheme, delivered by Salix and run by the Department for Energy Security and Net Zero, is constantly encouraging us to look at new technologies, fresh approaches and to be innovative in our outlook.
Whilst the schemes look for a holistic approach to managing building stock and we encourage a fabric first approach, it aims to specifically remove old stock of fossil fuel boilers, and to replace these with a type of heat pump. The preferred replacement is often air source, ground source or water source heat pumps.
However, a range of low carbon technologies are also considered, including district heating, hot water electric point of use heaters, solar thermal and biomass boilers, among others. For example, as part of Phase 1 Public Sector Decarbonisation Scheme, Leeds City Council implemented a district heating network powered by household waste to replace old inefficient gas boilers, as well as installing multiple energy efficient technologies, such as solar panels and LEDs, to reduce its carbon footprint.
Embracing change
Heat pumps come in a variety of designs but are mainly categorized as air source (air-to-air or air-to-water), ground source or water source heat pumps. As technology advances, a variety of refrigerants are being used to enable the right technology application to be applied to the right building design.
Heat pumps generally work well with low flow and return temperatures and being much lower than conventional fossil fuel systems, they often require some infrastructure enabling works and larger heat emitters (e.g. radiators), including the fabric first approach. However, this is not always the case and there may be sound reasons why this is not possible in all applications.
The idea is that by taking a fabric first approach to buildings, to ensure that they are as efficient as possible in terms of heat retention, we are then able to size and operate heating systems aligned to the improved peak heat loss figures, at low temperatures and improve the coefficiency of performance. In simple terms, we are replacing an old, inefficient fossil fuel boiler, with improved insulation and a new, efficient, electrical heat pump system to achieve the same or improved comfort levels, whilst at the same time, being more efficient and importantly, greener, by saving on carbon. It’s a bit like trying to get old, inefficient cars off the road!
To determine, what type of heat pump is best for each building, our public sector colleagues will normally engage with qualified architects to determine the fabric first approach and then mechanical and electrical consultants, to carry out feasibility studies to determine the works required, the sizing of the equipment in order to meet the peak load of any building. This will capture any enabling work and focus the task on what type of heat pump is right for your particular application.
For example, Derby College’s installation of water source heat pumps utilises natural resources by drawing water from the nearby Ouse River. It serves as a heating system, replacing gas boilers and contributing to the decarbonisation of the buildings heating. Additionally, they implemented Genius Controls, which operate similarly to movement sensors, regulating heating based on room occupancy.
Bridlington Hospital undertook a transformative project, which involved employing an air-source heat pump capable of meeting 100% of the hospital’s demand. It also included thermal insulation, modifications to air handling units, and system optimization, to enhance energy efficiency across the hospital estate. Additionally, the integration of 1,600 solar PV systems ensures 100% renewable electrical supply for the heat pumps, leading to zero-carbon heat generation.
Rather than using a heat pump, Exmoor National Park overcame its isolated location by incorporating a biomass boiler. It is situated in an off-grid location with no mains gas, electricity, or water and an ageing oil. Public Sector Decarbonisation Scheme funding helped facilitate a biomass boiler fuelled by local wood resources, along with additional battery capacity for storing energy from existing wind turbines and solar panels. Advanced building energy management systems were also introduced to optimise heating efficiency based on user demands and external conditions. Energy monitors were integrated into their existing wind turbine, solar panels, and batteries, providing real-time data on renewable energy generation. The initiative achieved a lifetime carbon saving of 605 tonnes of carbon dioxide.
These three examples alone are estimated to achieve lifetime carbon savings of 2,305 tonnes of carbon dioxide.
Heat pumps are most definitely here to stay, and the financial support offered from the Public Sector Decarbonisation Scheme from the Department for Energy Security and Net Zero has been instrumental in providing opportunity for public sector clients to launch into their strategic management of building stock, with a low carbon, sustainable, green approach.
