RENEWABLE ENERGY


Best practice for integration of renewables


T


Andrew Harrop, global director, regional sales enablement centres at Armstrong Fluid Technology discusses best practice for integrating renewables in public sector buildings


he UK Government’s plan for a total £200 million investment in rooftop solar power and renewable schemes for public sector buildings, announced in March this year, is set to improve


energy conditions for NHS trusts, schools and councils around the country. NHS energy bills, for example, have doubled since 2019, and the projections of £45,000 of savings per project per year are a great step in securing the country’s energy security and improving public sector sustainability.


Recent history suggests the optimism around


renewables is well placed, with projects like the car park solar canopy for Wharfedale Hospital in Leeds already producing savings of £75,000 a year, reducing emissions by 43.7 tonnes in the process1


. However, it’s important to hold on to a mindset of continuous optimisation. Too often, solar and other renewable technologies are seen as purely bolt-on solutions, with a focus solely on payback times and energy produced. If the mission is to decarbonise public sector buildings and bring down bills, it’s imperative that careful analysis is made of the efficiency of building systems, over the long term, rather than just incorporating renewable technology and calculating the price of the energy generated. Without taking advantage of modern advancements in HVAC technology and smart building systems, we’re only fighting half the battle. Best practice advocates a holistic approach to integration of renewables, wherein various types of energy can be stored and deployed in the most efficient way possible. For this reason, it’s important to hold a mindset of energy agnosticism, whilst allowing for advancements in the future such as heat pumps or biomass to be integrated as seamlessly as possible.


By no means is this downplaying the value of technologies such as solar as a renewable resource. In 2015, for example, Armstrong Fluid Technology completed a major renewable energy project at its Manchester site. A 250-kilowatt peak (kWp) solar photovoltaic panels system was successfully installed over a roof area of 1,550m2. The system has been up and running since January 2016 and has already started to reduce the carbon emissions and the costs associated with our electricity consumption. In 2023 we generated 185,028 kWh of electricity. We exported 27,100 kWh of electricity to the grid. The balance was consumed in our plant.


There’s fantastic precedent within the public sector too, including the solar farm for the Royal Wolverhampton NHS Trust, which is expected to power the entire hospital site for 288 days a year, saving around £15-20M over the next 20 years2


. This particular site is located at a


former landfill, and displays the kind of joined up imaginative problem-solving the country needs as it invests more and more in district energy and sector coupling projects. In reality, however, decarbonisation may begin with the energy source, but the bottom line is that efficiency begins in the plant room.


HVAC responsibilities


It’s no secret that HVAC is responsible for a large percentage of the energy usage in public sector buildings like hospitals and schools. In hospitals the impact is especially high, sitting at around 40-60% of the building’s footprint, or even 75% if you count water heating. Aside from purely providing electrical energy, solar can also be a key part of providing heat energy to be held in thermal stores.


One technique involves a biodegradable


propylene glycol solution, which is circulated through the solar array. The solar array heats the water/glycol mixture which, in turn, heats the lower portion of the stainless steel solar cylinder. Where there is insufficient solar energy available to achieve the required 60°C for DHWS, only then are back-up boilers brought in for the top-up. One of the advantages of a well stratified thermal store is the ability to integrate various heat sources such as heat pumps and biomass. Hot water rises and cold-water sinks, so lower temperatures from solar thermal or heat pumps are fed into the bottom of the store, medium temperatures such as from condensing boilers are fed into the middle of the store, and higher temperatures from biomass are fed in towards the top of the store. By using modern control technologies, we can make sure that the system is always operating


18 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JULY 2025


individual components within the curves that make them the most efficient, for example, optimising part-load efficiency of pumps. Importantly, effective control using a thermal store can also integrate low and zero carbon technologies which, as Figure 1 illustrates, have very different optimum operating temperatures.


Building for the future


The only ‘bolt on’ thinking we should be doing is around our plant design itself. By investing in energy-agnostic plant rooms, we leave the door open for future investment and secure our energy security by providing an environment wherein many buildings can benefit from different types of energy interchangeably. Modern plant rooms are manufactured off- site, and designed in a modular fashion, which leaves room for expansion in the future as well as streamlining on-site delivery and installation. If we’re going to be investing in the efficiency of HVAC systems in the NHS, for example, we must stress the value of a well-optimised plant room in the heart of the building, as this is where we see the majority of savings made in energy upgrades in our experience. The savings come from the efficiency of the new equipment, but also from the advanced control systems integrated within smart pumps which ensure that pumps are staged on and off in harmony with each other to meet loads in the most efficient way possible. As difficult as this kind of joined up thinking can be in the wider world of private and Government investment, when it comes to public-sector buildings, our thinking should be completely joined up.


1. Leeds Teaching Hospitals moves closer to achieving net zero objectives with innovative solar canopy installation - Leeds Teaching Hospitals NHS Trust


2. 2 Solar power investment in hospitals welcomed | DAUK


Read the latest at: www.bsee.co.uk


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38