BSEE ENERGY MANAGEMENT
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THE HEALTHY HEATING CHOICE Making great savings with CHP
Combined heat and power (CHP) is best suited to buildings with a 24/7 demand for heating and hot water. A Dachs Mini‐CHP unit, installed at Cockermouth Community Hospital and Health Centre, highlights the benefits of CHP in healthcare applications, while demonstrating the importance of correct design, commissioning and ongoing monitoring. Remeha CHP’s National Sales Manager, Paul Wilson, explains.
t’s no secret that healthcare facilities such as hospitals can make great savings by reviewing their energy outgoings. Currently, electricity makes up more than 50 per cent of a hospital’s energy costs. This consumption is also set to rise due to the increased use of specialist medical equipment that generally relies on electricity. What’s more, heating can account for as much as 60% of the total energy bill in a typical healthcare building. Just 1°C of overheating can increase fuel costs by around 8%.
Enter CHP, which is likely to save the NHS £26.4 million a year according to a report from the Sustainable Development Unit (SDU) for NHS England and Public Health England. This is because CHP is approximately 30 per cent more efficient than relying on traditional heating plant and electricity supplied solely from the grid.
CHP systems burn natural gas to generate heat, while providing electricity to supplement or replace the grid supply. Buildings with CHP can produce electricity at gas prices, which is approximately eight pence cheaper per kWh than buying it directly from the grid. Also, in comparison, CHP electricity doesn’t suffer losses resulting from moving power over large distances, resulting in a more efficient process. By generating electricity on site, energy bills can be reduced by around 20% compared to conventional power generation. CHP is great for buildings with high and continuous, year-round heating loads like hospitals; because of the long running hours, these buildings can achieve the most energy efficient operation. However, for CHP’s potential to be fully realised, systems need to be carefully and correctly designed and
commissioned. It’s important for all parties to work together at the early stages of a project, and for the CHP supplier to be involved in initial discussions about system design. The key to ensuring CHP is properly specified and delivers savings is to
keep it as small as possible. Oversized CHP units are not able to run if the heat demand is not present, and as a result the anticipated electricity will not be generated.
The system should be sized so that the base load heating requirements can be met largely by the CHP unit alone. This will result in the continuous generation of low cost, low carbon electricity as a by-product of producing base load heating. Cockermouth Community Hospital and Health Centre in Cumbria is a good example of how system design and ongoing monitoring, can ensure maximum savings from CHP are achieved. The facility comprises a purpose built 11-bed GP/nurse led unit for adult patients, two GP practices, a pharmacy and outpatient and community clinics. Provision has also been made for a diagnostic suite, a dental practice and minor surgery theatres. The original cottage hospital, which was almost 100 years old, was rebuilt in 2013, with the aim of
accommodating all the town’s primary healthcare services under one roof.
The Cockermouth team specified CHP as part of an energy and carbon saving strategy to meet long- term environmental goals and BREEAM targets. An R-Gen SenerTec Dachs 5.5kWe unit was installed to provide hot water for general medical needs and electricity to supplement the main grid supply and power the plant room.
Initially, when the hospital engineer integrated it with the Building Management System, the CHP unit did not run as expected. The running temperature for the heating system was set too high and the central heating pumps were operating in excess of the design required flow rate. As a result, the CHP unit would only run for a few minutes first thing in the morning and then stand idle for the rest of the day, significantly reducing the efficiency of the system. The hospital uses radiant panels to distribute heat to the occupied spaces. Because of the excessive water velocity, they were struggling to deliver the required heat. As a result, the thermostatic controls were
continually demanding more heat from the boilers.
The R-Gen SenerTec Dachs is designed to provide pre-heated feed water to a 750-litre buffer vessel, which stores the heat until it is required. However, the excess water velocity was allowing the heat from the boilers to enter the buffer vessel, affecting the heat distribution from the CHP unit.
When one of our expert technical sales managers visited the hospital, he quickly realised that the CHP unit had been running for only a fraction of the time possible. By simply tweaking the boiler temperatures down by one or two degrees, he could get the CHP running as intended. The hospital’s maintenance engineer also reset the system pumps reducing the velocity in the system ensuring even distribution throughout the heating system. The unit is now running almost continuously, meaning the hospital is benefiting from significant energy savings. In fact, the hospital’s energy bill has been reduced by around 30 per cent.
This example illustrates how important it is to be mindful of the building dynamics and how the end user intends to use the heat and power. An early conversation with the controls engineer to make sure the BMS is set up with CHP in mind is also crucial – as is ongoing monitoring. CHP is a well-established, reliable technology with numerous successful installations throughout the UK, and across the world. However, if CHP is to deliver cost and carbon savings, the importance of correct design, commissioning, monitoring and maintenance must be fully understood.
uWynne Evans, the Welsh tenor and star of the ‘Go Compare’ adverts, with BESA Head of Wales Catherine Griffith‐Williams, BESA President Malcolm Thomson and Wales Region Chairman, Owain Dobson.
he outlook for the industry in Wales is extremely
promising, according to the President of the Building Engineering Services Association (BESA).
Malcolm Thomson told an industry audience that Wales was “in a good place” despite the “cloud of uncertainty swirling around the wider economy as we prepare for yet another election and the dreaded Brexit talks”.
He pointed to major infrastructure projects like the Swansea Bay tidal lagoon and “an extremely ambitious plan” to build 20,000 new affordable homes backed by a
20 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JUNE 2017
£1.5bn finance package supported by the Welsh Government. Mr Thomson said he had detected a real determination in Wales “to make sure your development plans are not knocked off course by events elsewhere”. However, he warned that major projects would put pressure on the pool of available skilled labour and urged the country to match investment in projects and planning with a significant investment in bringing new people and new skills into the industry.
According to recent research carried out by BESA Training, the building engineering sector in Wales
uThe Cockermouth team specified CHP as part of an energy and carbon saving strategy. A R‐Gen SenerTec Dachs 5.5k unit was installed to provide hot water and electricity to supplement the main grid supply and power the plant room.
CHP systems burn natural gas to generate heat, while providing electricity to supplement or replace the grid supply. Buildings with CHP can produce electricity at gas prices, which is approximately eight pence cheaper per kWh than buying it directly from the grid.
’ Wales is ‘in a good place’ says BESA President
has enjoyed significant growth in manpower demand over the last 10 years. The rate of growth will slow a little over the next five years, but demand for mechanical trades will continue to rise by up to 11% between now and 2020 and for electricians by approximately 9%. Mr Thomson told the annual BESA Wales dinner that this made it extremely important for the industry to “grow its own talent” and make full use the targeted training courses and funding streams now emerging for apprenticeships.
“When it comes to funding for training, we must use it or lose it – that’s the deal,” he said. “Funding is
coming through and it is up to us, as employers, to make sure that money stays in our sector and helps finance the pipeline of talent that will be needed to deliver all these exciting new projects.”
The Association’s Head of Wales, Catherine Griffith-Williams, echoed the President’s comments and said this was a great opportunity for BESA members.
“MEP and building engineering apprenticeships are an ideal way of supplying the competent workforce we will need for the exciting wave of investment coming into Wales over the next couple of years,” she said.
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