In March this year, the Government announced plans for a total £200m investment in rooftop solar power and renewable schemes for hundreds of schools, NHS Trusts and communities across the UK. The investment is to be managed through a partnership between Great British Energy, the Department for Education and the Department for Health and Social Care. Around £100m has been allocated for nearly 200 NHS sites, with the fi rst solar panels expected to be installed by the end of this summer. The benefi ts for healthcare sites could be considerable. The solar farm for the Royal Wolverhampton NHS Trust, for example, is expected to power the entire hospital site for 288 days a year, saving around £15-20m over the next 20 years. But how can this investment in
technologies such as solar, biomass and heat pumps be optimised, to create the tangible fi nancial and environmental improvements that are critical for healthcare sites? The gains made from on-site generation can so easily be lost due to the challenges of integrating (sometimes multiple) renewable devices with other parts of the HVAC system. Challenges As Figure 1 illustrates, there are considerable diff erences between the optimum operating temperatures of the diff erent low and zero carbon technologies. The key challenge when designing renewables into a HVAC system design, therefore, is to integrate the low and zero carbon elements without compromising energy effi ciency of the various component parts of the system. There are two key factors when addressing these challenges. Firstly, an energy agnostic approach is important, to futureproof the site for expansion of renewables in the future. Thermal stores are therefore crucial, as they can eff ectively hold energy from various diff erent sources. Secondly, the HVAC control systems need to be capable of optimising the potential of all renewable energy sources as well as high effi ciency, low carbon components. Solar panels, for example, should be seen as one part of a holistic system which takes advantage of the effi ciency curves of all energy-consuming components across the system, such as pumps. Much of the best equipment to support solar integration is most effi cient while operating at part-load, staged in harmony with other system
components to meet demand at optimum levels. It’s also possible to leverage the connectivity and intelligence of smart HVAC equipment to selectively choose exactly when and how the new energy is deployed. Solar integration One eff ective integration method for solar, harnessing the capabilities of a thermal store, 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 insuffi cient 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 stratifi ed thermal store is that it has the ability to integrate various other 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, for example 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. Modern control technologies ensure that components in the system always operate within the curves at which they are most effi cient, which often involves pumps working at part-loads, and various elements are also most effi cient whilst running at optimum temperatures. Healthcare sites now have an opportunity
to make valuable reductions in energy costs. The key to translating government funding into tangible benefi ts, however, will be smart integration of all low and zero carbon components.
JN248
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 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
