Feeling the heat
Published: 15 October, 2010
Simon Potts and Andrew Miele explain why chp is so well suited to hotel and leisure buildings, and advise on how to make the most of your investment.
Combined heat and power (chp) is a well-established technology that produces electricity and usable heat in a single process. Simon Potts, managing director of Platignum Environmental Ltd (PEL, part of the HSE Group) says: “The key benefits of chp are all about efficiency. If you are looking at electricity produced at power stations for the national grid, around two thirds of energy consumed in producing electricity is simply lost through wasted heat and transmission losses.”
By contrast, the average efficiency of a chp unit is around 70%, with that figure rising to over 80% for some of the latest models. However as with most building services equipment, the key to reaping the benefits of chp lie in proper planning and good installation.
“You need to use all the heat to maintain high levels of efficiency,” says Andrew Miele, PEL energy and sustainability manager. “It is far better to slightly undersize a chp unit than to oversize. You will see a greater return on investment that way,” he adds. Miele recommends that the chp is not viewed as the sole source of heat and hot water. “You should calculate for 92% availability of the chp, so backup boilers will be required, but the chp should certainly be the lead boiler.”
The PEL team specialises in the supply of pre-packaged plant of all types, including low-carbon technologies, so they consult closely with clients to ensure that the right equipment is specified and integrated with the existing building services. Miele and Potts stress the importance of considering the business objectives of installing chp before deciding on type and size of system.
“For example, your objectives may be to save money and to satisfy requirements for the business to be greener; or they may be to keep the building running in the event of power outages,” says Potts. “The business requirements will impact directly on the type, size and setup of the chp – or even whether it’s the right technology for the project.“
One of the most important steps to take is to understand a building’s heat profile through the seasons, and in the case of hotels even through each day. “Hotels often have a good idea of how heat is used in their buildings, so this is information that is easily to hand,” says Miele.
Since sizing the chp unit is so critical to attaining good performance, it is vital to ensure that the building is not wasting heat. “Poor insulation means that you will be using more heat than you need, and specifying a unit that is unnecessarily large,” says Potts.
One area that is often overlooked is maintenance. As Potts says: “You can’t install a chp unit and then leave it alone for years. These engines run for 8,000 hours a year. If that were a car, it would be travelling half a million miles in a year. When you look at it that way, you see how crucial maintenance is.” Potts adds that in general, a chp unit will require maintenance every 1,000 hours, taking up to a day each time. “But that’s a lot less than you will need if it breaks down,” he points out.
Delivery of the chp unit is also another point to consider. Platignum Environmental supplies the units in a pre-packaged plug-and-play plant room. “We can supply the chp unit and any accompanying equipment such as backup boilers and controls in a single box,” says Potts. One of the advantages of prefabrication is that installation time is greatly reduced – especially in retrofit projects where the existing plant room is likely to be too small for a chp unit. With the chp unit set up and tested before it gets to site, there is also no need for on-site trades such as welding and associated ‘hot works’.
Developments in chp mean that this is no longer a technology reserved for larger installations. Potts says that smaller units offer the same benefits as larger ones: “CHP can now be applied to single-owner hotels as easily as the major chains. We offer financing arrangements that make it much easier to gain the benefits of chp with no capital outlay. Users simply pay for the gas, electricity and heat they use. We take care of the rest, including maintenance.”