Commercial & industrial heating 1 Hotel case study
Factfile
Projected energy use and consumption
Domestic hot water in guest rooms: 2,000 kWh
Domestic hot water in public areas and kitchens: 1,450 kWh
Spa pool: 400 kWh
HVAC(heating) of public floors: 2,000 kWh
HVAC (heating) of guest rooms: 2,100 kWh Total: 7,950 kWh
Heating sources
Boilers: 7,200 kWh (6 x 1,100 kWh) CHP: 500 kWh Biomass: 600 kWh Total: 8,300 kWh
Cooling consumption
HVAC (cooling) of public floors: 1,000 kWh
HVAC (cooling) of guest rooms: 1,000 kWh
Spa pool: 200 kWh Total: 2,200 kWh
Cooling source
Chillers: 5,400 kWh (4 x 1,350 kWh)
Absorption chiller: 190 kWh Total: 5,590 kWh
Source: Electra (Westminster), M&E consultant
Dave Bell (left) and Gidon Rotem take stock of hotel’s heating system, which includes six cast-iron non-condensing boilers >
uses it to produce cold water. This will be used in the air conditioning for the hotel’s public areas and four below-ground floors. Although Rotem cannot currently quantify the
carbon savings this will achieve, he insists they will be significant, particularly as the public areas and basement levels need to be cooled throughout the winter because the lower levels are actually below ground level. Using waste heat to power the absorption chiller is around 80% cheaper than using grid electricity, he estimates. The hotel owners were keen for the building’s
heating system to include the best balance of environmental benefit, low running costs and high reliability. There was also a requirement to include renewable technologies to meet the requirements for planning permission. The exact mix of technologies will vary from project
to project and will depend on the exact expectations of the investors and the demands of the building. Although the CHP at the hotel runs on natural gas, 40% of the thermal capacity counts as renewable because the electricity is generated without the massive wastage of centrally generated electricity. In a hotel where there is 24/7 demand for electricity
matched to a high requirement for heat (including converting the heat to cooling using the absorption chillers), CHP is almost a must; it also gives security
54 CIBSE Journal October 2010
to the electricity supply, which is essential when you have a luxury hotel full of paying guests. The biomass boiler is attractive because the fuel is deemed to be completely carbon neutral. These two technologies cover approximately 15% of the designed heat load
We want to be one of the greenest
hotels in London, and we are winning business on the back of our green policies
and are designed to be the lead heat generators. The benefit is optimised when these technologies run constantly for long periods. The high efficiency boilers will only fire if demand exceeds this level. The whole system is controlled by the main building management system. Because the hotel has only been open six months,
the building services team has yet to complete any long-term performance measurement on the heating, cooling and hot water system. Rotem says he has not yet had enough data relating to the hotel’s actual energy consumption to compare against the design assumptions (see factfile, left). However, he adds, first indications are positive, and some adjustments will be inevitable as the hotel goes through its first winter. l
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