Hotel HVAC Design: Guest Rooms + Central Plant Guide

What You Need to Know

Hotels are among the most complex buildings to design HVAC for. A single hotel contains guest rooms, lobbies, restaurants, commercial kitchens, conference rooms, back-of-house areas, laundries, plant rooms, and car parks. Each zone has different temperature requirements, ventilation rates, operating hours, and noise criteria. The HVAC system must handle all of these simultaneously while keeping energy costs under control.

Guest rooms typically use 4-pipe fan coil units or VRF systems with individual temperature control. Each room needs 10 L/s outdoor air per person (AS 1668.2:2024). Bathroom exhaust runs at 25 L/s minimum. Guest rooms must meet noise criteria of NC 30 to 35, which is stricter than offices and requires careful equipment selection.

Mechanical engineering design fees for a mid-size hotel of 50 to 150 rooms range from $30,000 to $80,000. Hotels run 24 hours a day, 7 days a week, so energy efficiency and Section J compliance have an outsized impact on operating costs compared to office buildings that shut down at night.

• Guest rooms (sleeping areas) need 10 L/s outdoor air per person. For a double occupancy room, this means 20 L/s minimum. The fresh air supply must be ducted and mechanically provided, not reliant on openable windows alone for NCC compliance. (AS 1668.2:2024)
• Bathroom exhaust must be at least 25 L/s per bathroom. En-suite bathrooms in guest rooms are typically exhausted through a central riser with a roof-mounted exhaust fan. The exhaust must operate continuously or be linked to the room occupancy sensor. (AS 1668.2:2024)
• Restaurants and dining areas need 10 L/s per person based on design occupancy. At a typical density of 1 person per 1.5 sqm, a 200 sqm restaurant needs approximately 1,330 L/s of outdoor air. (AS 1668.2:2024)
• Commercial kitchens need dedicated exhaust and makeup air systems. Exhaust rates are determined by the hood type and cooking equipment. Makeup air must replace the exhaust volume and be tempered (heated or cooled) to avoid thermal discomfort. (AS 1668.1, AS 1668.2:2024)
• Conference and function rooms need demand control ventilation. Occupancy varies from empty to full capacity. CO2 sensors must modulate the outdoor air rate between the minimum floor area rate (0.35 L/s per sqm) and the full occupancy rate. (AS 1668.2:2024, NCC 2025 Part J)
• Section J energy efficiency requirements apply to all hotel HVAC systems. Hotels classified as Class 3 (residential care) or Class 6 (restaurant) have specific energy targets. Insulation, fan power limits, time switches, and economy cycle requirements all apply. (NCC 2025 Section J)
• Noise criteria for guest rooms are NC 30 to 35. This is 5 to 10 points lower than typical offices (NC 40). Fan coil units, ductwork, and diffusers must all be selected and installed to meet this target. (AS/NZS 2107:2016)

The guest room floor plate is where the HVAC design effort concentrates. A typical guest room of 25 to 35 sqm needs a cooling capacity of 3.5 to 5.0 kW, depending on the facade orientation, glazing area, and internal loads. Each room gets its own fan coil unit (FCU) or VRF indoor unit, typically concealed in the ceiling or within a bulkhead above the bathroom. The unit connects to a central chilled water and heating hot water loop (for FCUs) or to outdoor VRF condensing units (for VRF systems).

Fresh air is supplied to guest rooms through a central outdoor air unit on the roof, ducted down through risers to each floor. A common arrangement is a corridor-based fresh air system where conditioned outdoor air is delivered to the corridor and enters rooms through transfer grilles or undercut doors. An alternative is direct ducted supply to each room, which gives better control but costs more in ductwork and riser space. The corridor approach is simpler but means fresh air enters the room at corridor temperature, not at the room's setpoint.

Bathroom exhaust is critical. In a 100-room hotel, the total bathroom exhaust volume is at least 2,500 L/s (25 L/s per room). This exhausted air represents conditioned air leaving the building. Heat recovery from the bathroom exhaust can recover 15 to 25% of the energy that would otherwise be lost. A plate heat exchanger or run-around coil on the exhaust riser preheats or precools the incoming fresh air. For a Sydney hotel operating 24 hours a day, this saves meaningful energy year-round.

Lobbies and atriums present a different challenge. These are large open volumes with high ceilings, significant glazing, and doors that open frequently to the outside. The cooling load is dominated by solar gain and infiltration. Dedicated air handling units (AHUs) serve lobbies, sized for the peak solar load plus the infiltration air that enters every time the front doors open. Revolving doors or air curtains reduce infiltration by 60 to 80% compared to standard sliding doors.

Hotel restaurants and bars need their own HVAC systems, separate from the guest room system. The occupancy density is much higher than guest rooms (1 person per 1.5 sqm versus 1 per 15 sqm), so the ventilation load is an order of magnitude greater per square metre. If the restaurant has a commercial kitchen, the kitchen exhaust system must be completely isolated from the dining area HVAC. Kitchen exhaust hoods generate 1,000 to 5,000 L/s of exhaust depending on the cooking equipment, and all of this volume must be replaced with tempered makeup air.

Conference and function rooms have the widest occupancy swing of any hotel zone. A 200-person function room might be empty for 18 hours a day and packed to capacity for 6 hours. Without demand control ventilation (DCV), the system runs at full outdoor air volume all the time, wasting energy. CO2 sensors linked to variable speed drives on the AHU supply fan modulate the outdoor air from the minimum floor area rate to the full occupancy rate as the room fills. This cuts the ventilation energy by 40 to 60% during low-occupancy periods.

Back-of-house areas including laundries, plant rooms, housekeeping stores, and staff offices have lower fit-out quality requirements but still need ventilation and in some cases cooling. Hotel laundries generate significant heat and moisture. A 100-room hotel laundry needs 3,000 to 5,000 L/s of exhaust to manage heat and humidity from commercial washers and dryers. This exhaust is another opportunity for heat recovery.

Central plant selection depends on hotel size. For hotels under 100 rooms, VRF systems can be cost-effective because they avoid the need for a central plant room, cooling towers, and chilled water pipework. For hotels over 100 rooms, a chilled water system with water-cooled chillers and cooling towers is typically more efficient and easier to maintain at scale. The central plant room needs careful acoustic treatment because guest rooms may be located directly above or adjacent to it.