Guest Room Area Zoning Control Strategy
The guest room area is the core zone for hotel HVAC zoning control, characterized by dispersed electrical loads, highly random usage periods, and high individualized guest demand. Five-star hotel guest room HVAC zoning control requires systematic design across three dimensions: vertical zoning, horizontal zoning, and individual control. According to Articles 7.3.5 and 7.3.6 of GB 50736 "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings," guest room HVAC terminals shall adopt independent control, and each room shall be capable of independently adjusting room temperature. In terms of vertical zoning, hotel guest rooms are divided by floor into three vertical zones: low zone, middle zone, and high zone. Due to the stack effect caused by building height and differences in solar radiation, the heating and cooling load difference between floors can reach 15%–25%. Guest rooms in the high zone (near the top floor) are affected by roof heat gain, with summer cooling loads 15%–20% higher than the low zone; guest rooms in the low zone have slightly higher winter heating loads than the high zone (affected by ground heat loss). Therefore, in vertical zoning, every 6–8 floors is set as one HVAC zone, with each zone provided with independent HVAC risers and fresh air branch ducts. In terms of horizontal zoning, the building is divided by orientation into four horizontal zones: east, west, south, and north. East-facing guest rooms receive strong solar radiation in the morning, with cooling load peaks occurring at 10:00–12:00; west-facing guest rooms receive strong solar radiation in the afternoon, with cooling load peaks at 14:00–16:00. According to Article 4.2.5 of GB 50189, HVAC zoning should account for differences in solar radiation, and east- and west-facing rooms should preferably be controlled as independent zones. Through horizontal zoning control, cooling supply can be flexibly adjusted according to the actual load demand of each orientation, avoiding energy waste caused by uniform cooling supply. At the individual control level, each guest room is equipped with an RCU smart thermostat with a temperature control accuracy of ±0.5°C. The RCU automatically switches operating modes based on guest occupancy status: when a guest checks in, the RCU automatically switches the room HVAC from standby mode (26–28°C in summer) to comfort mode (24°C ±1°C in summer); when the guest leaves the room (card removal and power cutoff), the RCU automatically switches to energy-saving mode (26–28°C in summer, 18–20°C in winter) and closes the curtains. The Marriott MIDS standard requires guest room thermostats to have four-speed fan control and temperature setting functions, with default set temperatures of 23–24°C in summer and 22–23°C in winter. The guest room fresh air system also adopts zoning control: each floor's fresh air plant room is equipped with one fresh air handling unit serving 8–12 guest rooms, with motorized control valves and constant air volume valves installed on the fresh air ducts to ensure a constant fresh air volume of 50–60 m³/h per guest room. Regarding guest room HVAC terminal types, five-star hotels typically adopt FCU (fan coil unit) + PAU (primary air unit) schemes or VAV (variable air volume) + PAU schemes. According to Article 7.5.4 of GB 50736, when a fan coil unit plus fresh air system is adopted, fresh air shall be supplied directly into the room and shall not be supplied after passing through the fan coil unit.
Public Area Zoning Control Strategy
Public areas are the hotel's image showcase, including the lobby, front desk, corridors, elevator lobbies, and other spaces, characterized by large space height, frequent personnel flow, and large instantaneous load variations. According to Article 7.3.8 of GB 50736 "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings," large spaces (height ≥6 m) should adopt stratified air conditioning, cooling only the lower occupied zone (below 2 m), while the upper space may adopt natural ventilation or mechanical heat exhaust. The floor-to-ceiling height of five-star hotel lobbies is typically 8–15 m, and stratified air conditioning can achieve energy savings of 30%–50%. Key points of lobby HVAC zoning control strategy: (1) Underfloor air supply: adopt seat air supply or floor air supply to deliver treated air directly to the occupant activity area (within 2 m above the floor). The supply air temperature is 2–3°C higher than conventional systems (16–18°C), which can extend the utilization time of natural cooling sources. The supply air plenum height of the floor air supply system should not be less than 300 mm, and the floor outlet air velocity should be controlled at 0.2–0.3 m/s to avoid draft sensation. (2) Side air supply: install nozzle air supply on the side walls around the lobby, with adjustable-angle nozzles, supplying air upward in summer (attached to the ceiling, utilizing the Coanda effect) and downward in winter. (3) CO₂ concentration control: install CO₂ sensors in the lobby occupant activity area (spacing not exceeding 20 m), and automatically increase fresh air volume when CO₂ concentration exceeds 800 ppm. Using CO₂ demand-controlled ventilation (DCV) technology, the lobby fresh air volume can be adjusted from 30% to 100% of the design value, saving approximately 40% of fresh air handling energy. (4) Full fresh air operation in transition seasons: the lobby space is large and the building envelope has strong thermal storage capacity; utilizing night ventilation for pre-cooling can reduce the next day's peak load by 10%–15%. The front desk area, due to its low personnel density but frequent visitors, should have HVAC control interlocked with the lobby but independently adjustable. Corridors, as transition spaces, may have HVAC temperature set 1–2°C higher than guest rooms (25–26°C in summer), using constant air volume systems for cooling. Elevator lobbies require additional consideration of equipment heat dissipation loads due to elevator equipment heat gain; mechanical exhaust is typically installed at the top of the elevator shaft (exhaust volume calculated to remove heat dissipated by elevator motors). The atrium or lobby area may also consider installing a radiant cooling ceiling system, circulating 16–18°C chilled water through ceiling panels to remove sensible heat loads. Radiant cooling can handle 50%–70% of the lobby's sensible heat load, combined with an independent outdoor air system (DOAS) to handle latent heat loads and CO₂. Article 7.3.9 of GB 50736 recommends radiant cooling and heating terminals for large spaces. The Marriott MIDS standard requires that HVAC systems in key public areas such as the lobby and front desk be provided with standby units to maintain basic cooling capacity when the main unit fails.
Food & Beverage and Meeting Area Zoning Control Strategy
The dining area and the meeting and banquet area are key zones for zoned air-conditioning control in hotels, characterized by high occupant density, drastic load variations, and concentrated usage periods. In accordance with Article 7.3.7 of GB 50736 "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings," air-conditioning systems in densely occupied spaces such as restaurants and banquet halls shall be equipped with adjustable fresh-air ratios based on changes in occupant density. Zoned control strategy for the dining area: different dining venues such as Chinese restaurants, Western restaurants, and bars require independent air-conditioning and exhaust systems due to differences in operating hours, occupant density, and cooking methods. The occupant density of Chinese restaurants is 1.2–1.5 persons/m², with a cooling load index of approximately 200–280 W/m²; the occupant density of Western restaurants is 0.8–1.0 persons/m², with a cooling load of approximately 150–200 W/m². The dining area air-conditioning must be interlocked with the kitchen exhaust system: kitchen exhaust volume is designed at 40–60 air changes per hour, and the dining area make-up air volume is designed at 80%–90% of the exhaust volume to maintain a slight negative pressure in the dining area (−5 to −10 Pa). The kitchen air-conditioning shall adopt an independent system, and supply air outlets should not be located directly above the cooking stoves to avoid affecting the combustion efficiency of the burners. As the largest multifunctional space in a hotel, the banquet hall has particularly complex zoned control requirements. The banquet hall can be partitioned into 2–4 independent banquet halls, each equipped with independent air-handling units and exhaust systems. According to Article 7.3.10 of GB 50736, multifunctional halls shall have independent air-conditioning regulation capability when partitioned. Each independent zone is equipped with an independent thermostat (temperature control accuracy ±1°C), and the supply air system uses motorized control valves to achieve zoned supply air volume control. Among the air-conditioning loads of the banquet hall, the occupant load can account for 60%–70% (occupant density calculated at 1.0–1.5 persons/m²), so fresh-air volume regulation is a key energy-saving measure. CO₂ concentration sensors and occupant counting systems are installed to dynamically adjust the fresh-air volume based on the actual number of occupants. Displacement ventilation is recommended for the banquet hall, with supply air outlets set at the floor or under the seats, a supply air temperature of 18–20°C, and exhaust outlets set at the upper level. Displacement ventilation can improve ventilation efficiency by 50%–200% and improve indoor air quality. Door-control interlocking for meeting rooms: when the meeting room booking system indicates the start of a meeting, the air-conditioning system automatically switches to the set mode; after the meeting ends, it automatically switches to the energy-saving mode. The air-conditioning system of meeting rooms should adopt a VAV variable air volume system, with each meeting room independently controlling its supply air volume. Article 7.5.6 of GB 50736 recommends that small and medium-sized spaces such as meeting rooms adopt variable air volume systems. The Marriott MIDS standard requires that the banquet hall air-conditioning system be capable of independent operation in partitioned mode, with each partitioned zone maintaining at least 50% of the supply air capacity.
Zoned control strategy for the wellness and back-of-house areas
The functional characteristics of the wellness area (fitness, SPA, indoor swimming pool) and the back-of-house area (offices, staff canteen, laundry) differ significantly from those of guest rooms and public areas, and targeted zoned control strategies need to be formulated. In accordance with Articles 7.3.11 and 7.3.12 of GB 50736 "Code for Design of Heating, Ventilation and Air Conditioning of Civil Buildings," high-temperature and high-humidity spaces such as swimming pools shall be provided with independent air-conditioning systems and condensation prevention measures. Control strategy for the indoor swimming pool area: the indoor design parameters of the swimming pool are a temperature of 28–30°C, a relative humidity of 50%–65%, and 6–8 air changes per hour. The swimming pool area is one of the most energy-intensive areas of a hotel, with an energy density of up to 500–800 W/m². The control focus is dehumidification and condensation prevention, through the configuration of dedicated dehumidification heat pumps (heat recovery efficiency up to over 80%) to recover heat from the exhaust air for heating the pool water or preheating the fresh air. The swimming pool air-conditioning system is recommended to adopt independent constant-temperature and constant-humidity air-handling units with electric heating as auxiliary heating. SPA area control strategy: the temperature and humidity requirements of the SPA area are similar to those of the swimming pool but more stringent, with a temperature of 26–28°C and a relative humidity of 50%–60%. The ventilation volume of the SPA area is designed at 60–80 m³/h per person, and the supply air should adopt a slight positive pressure method to prevent odors from spreading to the corridors. Load characteristics of the fitness area: the fitness area has a high occupant density (0.5–0.8 persons/m²), and the heat dissipation of occupants during exercise is approximately 3–5 times that in a sitting state. Therefore, the cooling load index of the fitness area is as high as 250–350 W/m², and the fresh-air volume is designed at 50 m³/h·person. The fitness area air-conditioning should adopt an independent all-air system (AHU), with a supply air temperature of 14–16°C, and supply air outlets should avoid blowing directly on people. CO₂ sensors are installed to link with fresh-air regulation to maintain the indoor CO₂ concentration below 600 ppm. Control strategy for the back-of-house area: (1) Offices are designed as ordinary comfort air-conditioning, with a set temperature of 24–26°C. (2) The staff canteen air-conditioning is interlocked with the main kitchen exhaust to maintain a negative pressure state. (3) The laundry area requires independent air-conditioning and exhaust systems, with the exhaust volume calculated to eliminate equipment heat dissipation and steam volume, at 15–20 air changes per hour. The laundry has low temperature control requirements (can be relaxed to 30–35°C), but sufficient ventilation must be ensured. The air-conditioning control systems of all areas should be uniformly connected to the BAS platform to achieve centralized monitoring and energy management of each zone through the central control room. The BAS system can set the operating schedules of the air-conditioning systems in each area and control different areas by time period to avoid the operation of back-of-house air-conditioning during non-operating hours. GB 50314 "Standard for Design of Intelligent Buildings" requires that the BAS system of a five-star hotel cover all mechanical and electrical equipment and have energy consumption statistics and analysis functions.