Airport case studyCutting terminal HVAC energy by 21% with two HVLS fans
A 4,645 m² section of a passenger terminal was cooled and heated by a conventional HVAC system working against the building. Two 7.3 m high-volume, low-speed fans kept passengers comfortable at a higher set point, and metered HVAC energy fell on every day of the trial. The results were so convincing that Aena has since installed HVLS fans in 20 airports across Spain.
Energy data recorded during on-site trials at Valencia Airport.
01The challenge
Airport terminals are among the hardest spaces to keep comfortable: high ceilings, large glazed areas, constant passenger flow and air conditioning that runs for most of the year. In the hot Valencian summer the terminal relied heavily on cooling. In winter the opposite problem appeared. Warm air from the heating rose to the roof and stratified (layered), leaving more than 5°C between the upper and lower floors, with the heat sitting where nobody needed it.
02The solution
Two HVLS fans were hung in the test section alongside the existing HVAC system. Turning slowly, each one moves a large column of air down to the floor, where it spreads out across the terminal. Nothing else about the heating or cooling system had to change.
How the fans change the terminal
The 4,645 m² test area in 3D. Each particle is a parcel of air: orange shows the slow destratification airflow in winter, blue the faster cooling airflow in summer. Step through the scenes, or drag to look around.
Schematic view. Colours are illustrative; the more-than-5°C difference between the upper and lower floors was recorded at Valencia.
Summer: cooling without the cost
The large, slow-moving column of air creates a gentle, constant breeze at floor level. For passengers this feels 4–5°C cooler, so the airport could raise the HVAC set point and still keep the terminal comfortable, saving energy every hour the system runs.
Winter: heat back where people are
Running slowly, the fans push warm air down from the roof and mix it through the space. The terminal moves from stratified (layered) to destratified (even), holding a consistent temperature floor to ceiling while the heating works less.
03The results
To produce a fair comparison, the air conditioning and ventilation serving the test area were isolated and metered, and spot checks were made on how comfortable passengers felt. Over 15 days, average HVAC energy fell from 7,258 kWh a day without the fans to 5,729 kWh a day with them: 1,529 kWh a day, a 21% reduction.
Energy data recorded during on-site trials at Valencia Airport.
HVAC energy was lower on every day of the trial
HVAC energy per day, kWh
04The outcome
The trial was so successful that Aena rolled HVLS fans out across its network.
From one terminal trial to 20 airports
Following the results at Valencia, Aena has installed HVLS fans in 20 airports across mainland Spain, the Balearic Islands and the Canary Islands.
- Mainland Spain
- Balearic Islands
- Canary Islands
05Payback and return on investment
Set the electricity price, installed cost and expected price rise to see the payback and 10-year return. Both columns use the daily saving measured at Valencia; the right-hand column projects it across all three terminals.
Enter your current rate. The trial used €0.11/kWh.
Applied to years 2–10.
Test area · 2 fans, as metered
- Payback
- Saving, year 1
- Net saving over 10 years
- 10-year return on investment
All three terminals · projected
- Payback
- Saving, year 1
- Net saving over 10 years
- 10-year return on investment
Cumulative savings against installed cost, test area
0610-year savings
Year-by-year savings at the price and assumptions set above. The highlighted row is the year the test-area investment pays back.
| Saving that year | Cumulative, after installed cost | Energy saved | |||
|---|---|---|---|---|---|
| Year | Test area | All terminals | Test area | All terminals | Test area, to date |
07How the figures were calculated
- Data source: energy data recorded during on-site trials at Valencia Airport.
- Measured period: 15 days with the fans running and 15 days without, with the HVAC and ventilation serving the test area isolated and metered. Average use fell from 7,258 kWh/day to 5,729 kWh/day.
- Annual figures: the measured daily saving of 1,529 kWh is applied to 360 operating days a year, giving about 550 MWh a year in the test area.
- All three terminals: a projection that assumes the same saving and installed cost per terminal, three times the test area.
- Installed cost: the installed costs were based on 2010 prices. Enter your own quotation for an accurate figure at today's prices.
- Not included: fan electricity, maintenance, and any change in weather, operating hours or passenger numbers between the two periods. Results at other sites depend on building height, HVAC system and use.
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