Expert advice on using HVAC systems in hotel rooms

Hotel HVAC systems are an "invisible but fatal" component—they directly impact guest experience (noise, stuffiness, odor) and hotel profits (electricity costs, maintenance costs). The following recommendations, starting from the guests' most sensitive "feelings" and balancing energy conservation and operating costs, are divided into three dimensions: selection, operation and maintenance, and experience.

I. System Selection: Avoiding "Winning the bid with the lowest price, but paying high electricity prices"

This is the foundation for determining operating costs over the next few decades. Many hotels, in an effort to save on initial setup costs, often pay a high price later on.

1. Prioritize "total life cycle cost" rather than just looking at the purchase price.

Expert opinion: Air conditioning equipment is a long-term asset with a lifespan of 10-20 years. While choosing a low-priced brand during the bidding process may save 30% on initial installation costs, the energy costs may offset the initial savings within 3 years due to low energy efficiency and frequent maintenance.

Recommendation: The LCC of the equipment must be calculated, including the initial installation cost, the estimated electricity cost over 15 years, and the cost of maintenance and spare parts. Although using a high-efficiency main unit requires a higher initial investment, the difference can usually be recovered through energy savings within 2-3 years.

2. Choose the appropriate system type: Four-control vs. Two-control

This is a key point that directly affects guest comfort:

Dual-control system: The entire system is either entirely cooling or entirely heating. During seasonal transitions (such as late autumn or early spring), if the weather is hot at noon and cold at night, the dual-control system cannot simultaneously meet the guests' needs for cooling and heating, which can easily lead to complaints.

A four-pipe system can provide both cold and hot water simultaneously. This means that west-facing rooms can be air-conditioned, while cooler, shady rooms can be heated. Experts recommend that mid-to-high-end international hotels typically require a four-pipe air conditioning system to ensure personalized comfort for different guests.

3. System matching and redundancy design

Avoid overkill: Many design institutes calculate based on standard loads, but neglect the peak passenger flow in areas such as banquet halls and meeting rooms. If the equipment is too small, the cooling will be insufficient during peak seasons; if it is too large, the equipment will frequently start and stop at low loads, wasting energy and causing discomfort. Detailed load calculations based on the hotel's actual operating conditions are necessary.

Reserve expansion interfaces: If the current budget is limited, at least reserve room space and pipe interfaces for future equipment installation to avoid being unable to modify the system when the business format changes in the future.

II. Operation and Energy Efficiency Management: Refined Control of Every Unit of Electricity

Hotel occupancy rates fluctuate greatly, and using the same equipment strategy when the hotel is fully booked or vacant results in significant energy waste.

1. Implement "Guest Room Occupancy Control"

Data shows that hotel rooms are occupied for only 10-12 hours a day on average, and the average occupancy rate is often around 70% throughout the year, which means that the air conditioners are "idling" for a lot of time.

Strategy:

Standby mode: When a guest removes their card and leaves, the system should not be completely shut down (to prevent mold growth), but should automatically switch to "energy-saving mode". For example, the temperature is automatically set to 26°C in summer and 20°C in winter, and the fan runs at a low speed to maintain basic ventilation.

Pre-cooling/pre-heating: After check-in at the front desk, the system automatically turns on the air conditioning in the room in advance to ensure that the room reaches a comfortable temperature when guests enter, rather than turning it on after check-in.

2. Chilled water and fresh air outlet temperature settings

Chilled water temperature: Experts' experience indicates that the supply temperature of chilled water should not exceed 7.5℃ . If the temperature is too high, the fan coil unit cannot effectively dehumidify, resulting in a room that feels "cool" but is "damp and stuffy," a common problem in many low-quality hotels.

Fresh air treatment: Fresh air must be treated (pre-cooled and dehumidified) before being supplied to the room. If fresh air is supplied directly without treatment, the room humidity will soar. It is recommended to control the fresh air outlet temperature at 12-14℃ to ensure dehumidification effect.

3. Heat recovery technology

Hotels are places where both hot and cold water coexist. Waste heat generated by laundry rooms and chiller units can be recovered to heat domestic hot water (shower water). Utilizing a heat recovery system can significantly reduce boiler gas consumption.

III. Air Quality and Comfort: The Direct Experience of Guests

1. Humidity control is a "hidden killer".

Standard: The most comfortable relative humidity for the human body is 40%-60% . Measurements have found that the humidity in many hotel rooms often exceeds 70%.

Consequences: High humidity not only makes people feel stuffy (sticky), but also easily breeds mold and produces a musty smell, which is a fatal negative point for high-end hotels.

Solution: Improve the system's dehumidification capacity. During transitional seasons, even if not much cooling is needed, turn on the dehumidification mode to ensure that the guest rooms are dry and fresh.

2. Carbon dioxide concentration and fresh air

Pain point: In order to save electricity, the fresh air system is turned off, which leads to an increase in carbon dioxide concentration in the room, and guests will feel dizzy and lightheaded when they wake up in the morning.

Standard: The WELL standard recommends an upper limit of 800 ppm for optimal CO₂ concentration .

Solution: Install CO₂ sensors to adjust the fresh air volume based on the actual number of people (concentration). Reduce air supply when no one is present and automatically increase fresh air supply when someone is present, saving energy while ensuring fresh air .

3. Noise control

This is the number one guest room complaint. Whether it's an aging fan coil unit or a whistling sound caused by excessive airflow in the duct, both directly affect sleep.

Recommendations: Choose low-noise terminal equipment and use air chambers or silencers in the duct design to reduce airflow noise. Regularly tighten loose parts and clean clogged filters (clogged filters will increase noise and reduce airflow).

IV. Maintenance Pitfalls: Easily Overlooked Details

1. Inspection of solenoid valves

Many engineering departments neglect the maintenance of fan coil unit solenoid valves . If the valve is damaged and stuck, hot/cold water will continue to flow in the coil even when the thermostat is off, causing the room to be either too cold or too hot, and constantly wasting energy. A plan must be developed to regularly check the opening and closing status of the solenoid valves.

2. Prevent Legionella infection

For hot water systems, we must be vigilant about the growth of Legionella bacteria.

Operation: The hot water temperature needs to be briefly raised to above 60℃ for one day each month (this must be achieved at the end of the circulation system) for high-temperature sterilization to ensure the health and safety of guests.

Summarize

For hotel managers, the core logic of HVAC systems is: " Guests need comfort (suitable temperature and humidity, quiet environment, good air quality), while owners control costs (energy saving, long lifespan). "

Under construction: Don't skimp on upfront costs; four-way control, frequency conversion, and heat recovery are the directions.

During operation: Do not turn off the fresh air system, control the humidity, and make good use of the energy-saving mode when guests leave the store.

During maintenance: 7.5℃ chilled water is critical; solenoid valves and filters may seem minor, but they have a significant impact.