Optimising thermal comfort and energy efficiency in a sports hall: a thermodynamic simulation study
Praxis Resilient Buildings conducted an advanced thermodynamic simulation study to assess and improve the thermal performance of the new sports hall in Vila-seca.
Optimising thermal comfort and energy efficiency in a sports hall: a thermodynamic simulation study
Praxis Resilient Buildings conducted an advanced thermodynamic simulation study to assess and improve the thermal performance of the new sports hall in Vila-seca, Tarragona, designed by Pere Buil of vora arquitectes. This technical analysis was undertaken to guide design strategies for natural ventilation, solar control, and thermal envelope specification.
Climate and simulation tools
The Reus Airport IWEC II climate file (ASHRAE) was used to simulate outdoor conditions. With the airport located only 10km from the new sports hall, the data set provided a reliable foundation for analysing seasonal thermal loads and comfort.
Building envelope and baseline performance
The base-case building envelope included:
- Uninsulated floor slab (U = 1.77 W/m²·K)
- 13 cm of insulation in the walls (U = 0.29 W/m²·K)
- 30 cm of insulation in the roof (U = 0.15 W/m²·K)
- Standard double glazing (Ug = 2.8 W/m²·K, g = 71%)
- n50 = 3.0 ACH
- Lighting power density: 4.5 W/m²
Natural ventilation was enabled in the simulations when indoor air temperature exceeded 14°C and was higher than outdoor air temperature.
Design variables studied
Several strategies were evaluated across typical winter (January) and summer (July) weeks:
- Natural ventilation vs. uncontrolled infiltration-only
- Slab insulation (10 cm)
- Low-emissivity glazing
- Solar control glazing
- High-emissivity EPDM roof finish
- Daylight-responsive lighting control
Key winter findings
- Ventilation: Passive ventilation achieved >20,000 m³/h airflow without wind, thanks to cross-ventilation and stack effect.
- Comfort: Operative temperatures dropped below 14°C during early mornings but recovered due to internal gains.
- Humidity: Relative humidity remained below 70% during occupancy.
- Insulated slab: Surprisingly, this lead to worsened night-time comfort due to less heat input from the relatively warmer subsoil.
- Glazing and roof finishes: Minimal impact on comfort.
Key summer findings
- Temperature: Operative temps remained below outdoor conditions, peaking at 28°C thanks to efficient heat evacuation.
- Natural ventilation: >18,000 m³/h airflow enabled through stack and cross ventilation.
- Humidity: Passive ventilation kept RH <76% during weekdays.
- Solar control glazing: Delivered up to 2°C cooling benefit; however, cost-benefit vs. external shading warrants further study.
Lighting control and energy savings
- Daylight control showed negligible thermal impact but slashed electricity consumption by 88-90%, making it a highly recommended strategy.
Hourly overheating and overcooling analysis
- <14°C (overcooling): 16% of annual occupied hours
- >26°C (overheating): 19% of annual occupied hours
Recommendations
- Skip slab insulation: Not beneficial for thermal comfort
- Prioritise natural ventilation: Highly effective with stack and cross ventlation
- Low-e and/or solar control glazing brings little benefit
- External shading devices: required for the highly glazed north-west facing façade
- Implement daylighting control: Significant electrical savings
- Maintain 30 cm roof insulation regardless of surface finish
Control System Design
An automated Building Management System (BMS) is recommended, with sensors for:
- Outdoor conditions: Temperature, RH, wind, rain
- Indoor conditions: CO₂, temperature, humidity at 3 interior points
- Motorised control of facade and roof openings based on thresholds
Conclusion
The simulation study provided robust insights into how passive strategies can be fine-tuned to optimise comfort and reduce energy use in a mixed-mode, non-conditioned sports hall. With careful implementation, the Vilaseca pavilion stands to become a benchmark in passive design for educational sports infrastructure in Catalonia.