HVAC for Sporting Events and Games

Overview

Sporting venues present extreme HVAC challenges due to rapid occupancy changes, high metabolic heat generation, concentrated load periods, and event-specific requirements. System design must accommodate empty facilities during off-hours, moderate loads during practice sessions, and peak demands during events with thousands of spectators generating significant sensible and latent heat.

Load Characteristics for Sporting Events

Occupancy-Based Thermal Load

The total cooling load varies dramatically with event type and attendance:

$$Q_{total} = Q_{sensible} + Q_{latent} = \dot{m}c_p\Delta T + \dot{m}h_{fg}\Delta\omega$$

Where:

• $Q_{sensible}$ = sensible heat from occupants, lighting, and equipment (BTU/hr)
• $Q_{latent}$ = latent heat from occupant moisture generation (BTU/hr)
• $\dot{m}$ = mass flow rate of air (lb/hr)
• $c_p$ = specific heat of air = 0.24 BTU/lb·°F
• $\Delta T$ = temperature difference (°F)
• $h_{fg}$ = latent heat of vaporization ≈ 1,060 BTU/lb
• $\Delta\omega$ = humidity ratio change (lb moisture/lb dry air)

Metabolic Heat Generation by Activity Level

Per ASHRAE Fundamentals, metabolic heat varies with spectator engagement and athlete activity:

$$q_{metabolic} = N \times q_{person} \times AF$$

Where:

• $N$ = number of occupants
• $q_{person}$ = heat gain per person (BTU/hr)
• $AF$ = activity factor (1.0 seated, 1.3 standing/cheering, 4.0-6.0 active play)

Event Schedule Integration

Predictive Load Scheduling

HVAC systems must pre-condition facilities based on event schedules:

$$T_{precool} = \frac{V \times \rho \times c_p \times \Delta T_{desired}}{Q_{cooling} - Q_{building}}$$

Where:

• $T_{precool}$ = required pre-cooling time (hours)
• $V$ = venue volume (ft³)
• $\rho$ = air density ≈ 0.075 lb/ft³
• $Q_{cooling}$ = available cooling capacity (BTU/hr)
• $Q_{building}$ = building envelope load (BTU/hr)

gantt
    title Sporting Event HVAC Schedule Timeline
    dateFormat HH:mm
    axisFormat %H:%M

    section Pre-Event
    Setback Mode (55% capacity)     :a1, 00:00, 6h
    Pre-cooling (75% capacity)      :a2, 06:00, 2h
    Final conditioning (100%)       :a3, 08:00, 1h

    section Game Day
    Doors open                      :milestone, m1, 09:00, 0m
    Pre-game (50% crowd)            :a4, 09:00, 1h
    Game start                      :milestone, m2, 10:00, 0m
    First half (100% load)          :crit, a5, 10:00, 1h
    Halftime (peak concourse)       :crit, a6, 11:00, 20m
    Second half (100% load)         :crit, a7, 11:20, 1h
    Potential overtime              :a8, 12:20, 30m

    section Post-Event
    Crowd dispersal (80% capacity)  :a9, 12:50, 30m
    Cleanup mode (40% capacity)     :a10, 13:20, 2h
    Setback mode (30% capacity)     :a11, 15:20, 8h

Dynamic Load Management Strategies

Zone-Based Control

Implement separate control strategies for different venue zones:

Playing Surface Zone:

• Maintain strict temperature control (68-72°F for basketball/volleyball, 55-60°F for ice hockey)
• High air change rates: 6-12 ACH minimum per ASHRAE 62.1
• Minimize air velocity at playing level (<50 fpm to prevent interference)

Spectator Seating Zone:

• Occupied mode: 72-76°F, 30-60% RH
• Variable capacity staging based on ticket sales
• Increased ventilation during peak occupancy: 15 CFM/person minimum

Concourse and Amenities:

• Peak load during halftime and intermissions
• 100% occupancy factor during breaks
• Rapid recovery capability required

Halftime Load Spike Management

Halftime creates unique load distribution as occupants move from seats to concourses:

$$Q_{halftime} = Q_{concourse_peak} + Q_{restrooms} + Q_{concessions} - Q_{seating_reduced}$$

Peak concourse occupancy can reach 70-80% of total attendance simultaneously, creating:

• 40-60% increase in concourse cooling demand
• Reduced seating area loads (30-40% decrease)
• Concentrated latent loads near food service areas
• Restroom exhaust requirements spike to maximum

flowchart TD
    A[Event Schedule Input] --> B{Event Type}
    B -->|Regular Season| C[Standard Capacity]
    B -->|Playoff/Tournament| D[Maximum Capacity]
    B -->|Practice| E[Minimal Capacity]

    C --> F[Load Calculation]
    D --> F
    E --> F

    F --> G[Attendance Prediction]
    G --> H[Pre-cooling Start Time]
    H --> I[System Staging]

    I --> J{Game Phase}
    J -->|Pre-game| K[60% Capacity]
    J -->|Active Play| L[100% Capacity]
    J -->|Halftime| M[Zone Redistribution]
    J -->|Overtime| N[Extended 100% Mode]

    M --> O[Concourse Maximum]
    M --> P[Seating Reduced]

    N --> Q[Recovery Reserve]

Ventilation Requirements

ASHRAE 62.1 specifies minimum ventilation rates for sports venues:

• Spectator areas: 7.5 CFM/person
• Playing surfaces: 0.3 CFM/ft² (gymnasiums), 0.5 CFM/ft² (arenas)
• Locker rooms: 0.5 CFM/ft² plus shower exhaust

Total outdoor air requirement:

$$\dot{V}_{OA} = R_p \times P + R_a \times A$$

Where:

• $R_p$ = outdoor air rate per person (CFM/person)
• $P$ = anticipated peak occupancy
• $R_a$ = outdoor air rate per unit area (CFM/ft²)
• $A$ = zone floor area (ft²)

System Recommendations

Capacity Staging:

• Design for 20-30% overcapacity to handle extreme conditions
• Multiple chiller/RTU staging for part-load efficiency
• Variable speed drives on all major air handling equipment

Scheduling Integration:

• BMS integration with ticketing systems for real occupancy data
• Weather postponement flexibility with rapid reschedule capability
• Tournament mode for back-to-back events with minimal recovery time

Control Sequences:

• 2-4 hour pre-cooling based on outdoor conditions and event type
• Demand-controlled ventilation using CO₂ sensors in occupied zones
• Post-event setback to 55°F (winter) or 85°F (summer) within 30 minutes

Monitoring Points:

• Real-time occupancy counting at entrances
• Zone-level temperature and humidity
• Supply air temperature reset based on crowd density
• Return air CO₂ levels for ventilation adequacy

Components

• Game Schedule Input
• Practice Schedule
• Tournament Schedule
• Season Schedule Variation
• Weather Postponement Flexibility
• Schedule Change Accommodation