BSEE-OCT21-PG10.qxp_Layout 1 14/09/2021 11:46 Page 10


BSEE


CHP is frequently selected as an economic tool for space heating and domestic hot water production in high demand environments. But accurate CHP sizing at the design stage and regular maintenance and monitoring thereafter are essential for the anticipated performance and efficiency gains to be achieve. Mark Gibbons, Baxi Heating’s national sales manager CHP explains


COMBINED HEAT & POWER 3 steps to optimise CHP performance and benefits


The unit is controlled according to the heat demand, while the internal microprocessor controller tracks the electrical output to match the thermal output.


The Potterton Sirius three FS stainless steel boiler, which operates alongside the CHP to meet peak load, has a wide 9:1 modulation ratio for improved efficiency and boiler longevity. Its high gross seasonal efficiency of up to 97.5% reduces energy consumption and low NOx of under 24.6mg/kW minimises impact on the environment. It is supplied with the latest Siemens controls and state- of-the-art PCB to enable enhanced control options for energy efficient operation.


Robust maintenance Melwood House and Castle View House are identical new build developments in Berkshire which use CHP to meet energy requirements


n buildings with high energy demand, combined heat and power (CHP) offers an economic solution to generating heat and power that can reduce primary energy costs by up to 40% compared with conventional methods. But while the financial argument for CHP is certainly compelling, the potential benefits will only be achieved in a well-designed, well- maintained system.


I


Why are sizing and maintenance so central to CHP success? Put simply, if a CHP is not running, it won’t deliver the savings.


Maximising CHP success CHP operates most efficiently and


generates greater cost and carbon emissions savings if it is running constantly and, preferably, at full output. If oversized, a CHP unit will struggle to operate efficiently, reducing financial returns and emissions savings, as well as leading to maintenance and warranty issues. For this reason, accurate sizing at the design stage and robust maintenance and monitoring thereafter are key.


Let’s consider a real-world example that demonstrates the savings that this highly efficient technology can


deliver in a well-designed and well- maintained system.


Melwood House and Castle View House are two identical new build developments in Datchet, Berkshire, each housing 12 luxury two-bed apartments. For property developers Datchet Investments, it was important to select the most efficient and economical solution early in the design stage to serve the two private apartment schemes.


While CHP is frequently retrofitted to existing building installations, it can also be used to great benefit in new build developments to comply with low carbon requirements in Building Regulations Part L.


“After exploring various options, we concluded that CHP was the most effective solution to meet the energy requirements in our apartment buildings,” said Jas Gill, director at Datchet Investments. “Not only do the CHP systems fulfil Part L regulatory compliance, but they achieve excellent energy performance and lower running costs.”


In both properties, the identical CHP systems have been delivering significant efficiency benefits since they were installed nearly two years ago.


“We estimate that using CHP reduces our electricity costs alone by around £350 a month in each


building – and that’s not taking into account the heating bills,” added Mr Gill. “We’re extremely impressed with the performance of our CHP system, the benefits it is delivering, and the service we’ve received.”


Size accurately


The CIBSE Applications Manual AM12 for Combined Heat & Power provides useful information and guidance on how to go about selecting, installing and operating CHP plant. It states that as there is no straightforward way to size a CHP and the task of sizing falls to the designer, advice should be sought from suppliers at an early stage of design.


At Melwood House and Castle View House, Baxi Heating’s specialist CHP team began by carrying out an initial feasibility survey to calculate the demand and confirm that the sites were suitable for CHP. The next stage was to design the systems to meet the heating and hot water needs while providing on-site electricity.


They recommended installing a Remeha R-Gen SenerTec Dachs Gen 2 5.5 kWe CHP unit supported by a Potterton Commercial Sirius three 50 floor-standing condensing boiler. The Remeha CHP selected provides a thermal output of up to 14.7kW and an electrical output of 5.5kWe.


CHP – the process


CHP produces useful heat and electricity at the point of use in a single, highly efficient process. Rather than rejecting ‘waste’ heat to atmosphere like traditional power stations, CHP captures it and feeds it into the building’s heating network to produce useful thermal energy.


Using CHP is reducing electricity bills alone by around £350 a month in each building


A Potterton Commercial Sirius three FS condensing boiler operates alongside the CHP


10 BUILDING SERVICES & ENVIRONMENTAL ENGINEER OCTOBER 2021


This energy can then be used to provide primary space heating and/or pre-heat for domestic hot water within the building. At the same time, the CHP efficiently generates onsite electricity at lower gas prices, boosting the efficiency savings still further. The operating cost benefit of CHP will depend on the difference in gas and electricity prices. This is often referred to as the ‘spark gap’ or ‘spark spread’ – the wider the spark spread, the greater the return. With gas prices currently at around a quarter the price of electricity, CHP offers an attractive economic option – one that is capable of delivering payback within three years in a well-designed, well-maintained system. Additionally, onsite generation offers building operators with the opportunity to offset fluctuations of wholesale energy prices, ensuring greater energy resilience and control over energy costs. It’s worth noting too that our CHP units are compatible with a 20% hydrogen blend, making them future-proof for the next stage of the energy transition.


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


and monitoring Routine maintenance and continuous monitoring should be considered from the very start of the design process.


Since installing the system, Baxi Heating’s CHP technical engineers have provided regular scheduled maintenance of the plant room systems for Datchet Investments, including carrying out the first full service of both CHP units. This typically includes analysing and/or changing the engine oil, monitoring water quality and NOx emission levels, and checking and replacing service parts where necessary. All of which keeps the CHP operating at optimal


performance for maximum benefit to the building owners.


The CHP team additionally provides a remote CHP monitoring service for the two sites. Approximately 85% of reported CHP faults are able to be diagnosed, corrected and reset remotely, so this service effectively reduces downtime, inconvenience and unnecessary costs.


Will your CHP be an elephant in the plant room or a highly efficient technology? This best practice example illustrates the economic benefits that CHP can deliver. Sizing, maintenance and remote monitoring – work with experienced suppliers to get these aspects right at the design stage and the results will speak for themselves.


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