Energy Efficient, High Quality Air at Four Seasons Hotel

On the waterfront overlooking Victoria Harbor, Hong Kong, and the financial district, the Four Seasons Hotel redefines luxury and excellence in a city renowned for exceptional accommodation. As part of the prestigious International Finance Centre, it offers unrivalled links to Hong Kong station, with the famed Star Ferry steps away. Its 399 guest rooms include 54 suites, each reflecting the signature Four Seasons comfort and luxury. Wall-to-wall windows offer captivating vistas of the city, Victoria Harbor, Kowloon and the Peak. To ensure the standard of the air matched the quality of the furnishings, the Four Seasons chain selected Munters equipment for humidity control so that the indoor comfort is improved and mould can be prevented from attacking furnishings exposed to over 70%RH.

Other benefits of conditioning humidity and temperature with Munters systems is the energy savings and the ability to turn off room cooling when unoccupied and still ensure that the moisture in the room doesn’t create indoor air quality (IAQ) concerns, which some countries like Japan restrict below 70%RH as a sanitation law to prevent toxic moulds like Aspergillus.

Creating high air quality whilst lowering electical demand

Hong Kong’s leading designers were given a brief to create a high indoor air quality, whilst lowering the electrical demand. Looking at system options they understood that a dedicated outdoor air system DOAS delivering conditioned fresh air was energy efficient and provided ideal climate control for rooms which could have air conditioning cycled off at part load conditions or when unoccupied.

Working with Hong Kong Gas, an optimum Munters solution was selected with gas-reactivated desiccant with chilled water preconditioning rooms to below 60%RH. 15 Munters MX desiccant units with chilled water pre-coolers and gas reactivation were placed in the two plant rooms. Air is individually ducted into each of the 400 rooms to ensure humidity control and ventilation is accurate. The lobby and pool area also have humidity controlled ventilation air to maintain best practice standards.

The indoor air quality at the Four Seasons Hong Kong is world standard, and the building fabric and furnishings are preserved from the cycling humidity and mould accelerating effects experienced over 60%RH. Rooms which are unoccupied do not need air conditioning and deodorant to disguise the mould smell. Electrical demand is reduced by gas displacing electric duty and the ability to avoid running air conditioning in unoccupied rooms.

The benefits of dedicated outdoor air systems

By using dedicated outdoor air systems (DOAS) the zone units don’t have a latent load diluted by return air which creates a parasitic load on the air conditioning. Humidity control creates an environment where mould and mildew can be greatly reduced. Surfaces that get wet from water events such as spills, shower and bath splashes, roof leaks and window leaks, will dry much quicker.

The accelerated drying time greatly reduces the ability of mould to form. The conditions will be dry enough to minimise or eliminate condensation from forming on the PTAC cooling coils. Having dry PTAC coils eliminates the problem of PTACs overflowing in the interior of the building. Since people are more comfortable at higher temperatures when the air is drier, the hotel guests will tend to maintain the rooms warmer which can add up to significant energy savings. Recently the Hong Kong government mandated that HVAC has a set point of 25.5°C to reduce power consumption, and this would otherwise create difficulty in maintaining a reasonable humidity and comfort level.

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